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Introduction to Ecology

by: Raven Connelly

Introduction to Ecology EVE 101

Raven Connelly
GPA 3.56


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This 14 page Class Notes was uploaded by Raven Connelly on Tuesday September 8, 2015. The Class Notes belongs to EVE 101 at University of California - Davis taught by Staff in Fall. Since its upload, it has received 18 views. For similar materials see /class/187322/eve-101-university-of-california-davis in Evolution And Ecology at University of California - Davis.

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Date Created: 09/08/15
How Sustainable Agriculture Can Address the Environmental and Human Health Harms of Industrial Agriculture Leo Horrigan Robert S Lawrence Polly Walker Environmental Health Perspectives Vol 110 No 5 May 2002 pp 445456 Stable URL htt links39storor sicisici0091676528200205291103A53C4453AHSACAT3E20CO3B21 Environmental Health Perspectives is currently published by The National Institute of Environmental Health Sciences NIEHS Your use of the J STOR archive indicates your acceptance of J STOR39s Terms and Conditions of Use available at httpwwwjstororgaboutterms html J STOR39s Terms and Conditions of Use provides in part that unless you have obtained prior permission you may not download an entire issue of a journal or multiple copies of articles and you may use content in the J STOR archive only for your personal noncommercial use Please contact the publisher regarding any further use of this work Publisher contact information may be obtained at httpwwwjstororgjoumalsniehs html Each copy of any part of a J STOR transmission must contain the same copyright notice that appears on the screen or printed page of such transmission The J STOR Archive is a trusted digital repository providing for longterm preservation and access to leading academic journals and scholarly literature from around the world The Archive is supported by libraries scholarly societies publishers and foundations It is an initiative of J STOR a notforprofit organization with a mission to help the scholarly community take advantage of advances in technology For more information regarding J STOR please contact supportj stororg httpwwwjstororg Tue Jan 29 175744 2008 How Sustainable Agriculture Can Address the Environmental and Human Health Harms of Industrial Agriculture Leo Horrigan Robert S Lawrence and Polly Walker Center for a Livable Future Johns Hopkins Bloomberg School of Public Health Baltimore Maryland USA The industrial agriculture system consumes fossil fuel water and topsoil at unsustainable rates It contributes to numerous forms of environmental degradation including air and water pollution soil depletion diminishing biodiversity and sh dieoffs Meat production contributes dispropor tionately to these problems in part because feedinggrain to livestock to produce meat instead of feeding it directly to humans involves a large energy loss making animal agriculture more resource intensive than other forms of food production The proliferation of factory style animal agriculture creates environmental and public health concerns including pollution from the high concentration of animal wastes and the extensive use of antibiotics which may compromise their effectiveness in medical use At the consumption end animal fat is implicated in many of the chronic degenerative diseases that afflict industrial and newly industrializing societies particularly cardiovascular disease and some cancers In terms of human health both affluent and poor coun tries could bene t from policies that more equitably distribute high protein foods The pesticides used heavily in industrial agriculture are associated with elevated cancer risks for workers and consumers and are coming under greater scrutiny for their links to endocrine disruption and reproductive dysfunction In this article we outline the environmental and human health prob lems associated with current food production practices and discuss how these systems could be made more sustainable Key words diet environment health industrial agriculture sustainability sustainable agriculture Environ Health Perspect110445 456 2002 Online 22 March 2002 httpebpnetl nicks nihgovdocsZOOZI I 445 45 610n iganabstmct km The Union of Concerned Scientists I said that industrial agriculture views the farm as a factory with inputs such as pesticides feed fertilizer and fuel and outputs corn chickens and so forth The goal is to increase yield such as bushels per acre and decrease costs of production usually by exploit ing economies of scale Industrial agriculture depends on expen sive inputs from off the farm eg pesticides and fertilizer many of which generate wastes that harm the environment it uses large quantities of nonrenewable fossil fuels and it tends toward concentration of pro duction driving out small producers and undermining rural communities The fol lowing environmental and public health concerns are associated with the prevailing production methods Monocultures are eroding biodiversity among both plants and animals Synthetic chemical pesticides and fertilizers are polluting soil water and air harming both the environment and human health 0 Soil is eroding much faster than it can be replenished taking with it the land s fer tility and nutrients that nourish both plants and those who eat them Water is consumed at unsustainable rates in many agricultural areas Many of the problems inherent in indus trial agriculture are more acute when the out put is meat Our food supply becomes more resource intensive when we eat grain fed ani mals instead of eating the grain directly because a signi cant amount of energy is lost as livestock convert the grain they eat into meat Cattle are the most inef cient in their energy conversion requiring 7 kg of grain to produce 1 kg of beef compared to 41 for pork and 21 for chicken 2 Despite this inef ciency livestock diets have become higher in grains and lower in grasses The grain raised to supply feedlots cattle and factory farms chickens hogs veal calves is grown in intensive monocultures that stretch over thousands of acres leading to more chemical use and exacerbating attendant problems eg pesticide resistance in insects and pollution of surface waters and aquifers by herbicides and insecticides The use of grOWthpromoting antibiotics in animal agriculture is thought to be one of the factors driving the increase in antibiotic resistance in humans In addition the most prevalent foodborne pathogens are over whelmingly associated with animal products most of which come from factory farms and high speed processing facilities The crowded conditions in factory farms as well as many of their production practices raise ethical concerns about the inhumane treatment of animals Because they contain excessive amounts of fat particularly saturated fat and pro tein animal based diets are linked to many Environmental Health Perspectives VOLUME 110 NUMBER 5 May 2002 of the chronic degenerative diseases that are characteristic of affluent societies such as heart disease colon breast and prostate can cer and type II diabetes The animalbased diet that prevails in the industrialized world and is on the rise in many developing coun tries thus harms both the environment and the public s health High consumption of animal products in af uent countries can be placed in the context of broader global inequities between industrialized and developing countries Since 1950 meat consumption has doubled among the world s richest 20 whereas the world s poorest quintile has not increased its consumption of meat much at all 3 Some portions of the developing world are beginning to adopt Western dietary pat terns and as a result are experiencing an increase in the chronic diseases associated with a richer diet China offers a sobering case in point meat consumption nearly dou bled countrywide during the 19905 4 with the increase especially pronounced among urban residents This dietary shift is consid ered a major reason that chronic diseases have become a more common cause of death in China with acute diseases becoming less common because of improvements in water sanitation and immunizations According to Zhao et al 5 measles tuberculosis and senility were the three most common causes of death before 1950 but in 1985 malignant tumors cerebrovascular disease and ischemic heart disease were the most common To support its Westernizing diet China has also begun a shift toward more of the resourceintensive agricultural practices that Reviews Horrigan et al resources in particular fossil fuels and con sumption of some renewable resources is occurring faster than the rate of regeneration Developing a sustainable economy involves more than just a sustainable food system and the food system involves more than just agriculture However because agri culture can have such profound effects on the environment human health and the social order it is a critical part of any movement toward sustainability Sustainable agriculture systems are based on relatively small profitable farms that use fewer offfarm inputs integrate animal and plant production where appro priate maintain a higher biotic diversity emphasize technologies that are appropriate to the scale of production and make the transition to renewable forms of energy The average US farm uses 3 kcal of fossil energy in producing 1 kcal of food energy in feedlot beef production this ratio is 351 and this does not include the energy used to process and transport the food Sustainable systems involve less reliance on chemical inputs and decreased emphasis on economic efficiencies that shunt environ mental costs onto society The health of both the environment and humans would be enhanced if more of our farms made the transition to sustainable sys tems of production A more sustainable food system would involve closer connections between producer and consumer meaning more direct marketing of foods to local con sumers through farmers markets commu nity supported agriculture farms farmer cooperatives etc These localized marketing strategies mean shorter distances from the farm to the dinner plate and therefore less energy use for food transport In this paper we use examples from around the world to illustrate our points but we place heavy emphasis on the US food system because it represents one of the worst case examples of the pitfalls of indus trial agriculture The type of agriculture that has become conventional throughout the industrialized world is in historical terms a new phenomenon Humans have practiced agriculture for more than 10000 years but only in the past 50 years or so have farmers become heavily dependent on synthetic chemical fertilizers and pesticides and fossil fuel powered farm machinery In that halfcentury of ascendance industrial agriculture has substantially increased crop yields through highyielding plant varieties mechanization and synthetic chemical inputs For example US farmers were producing 30 bushels of corn per acre in 1920 whereas 1999 yields averaged about 134 bushels per acre an increase of almost 350 67 446 The higher yields of industrial agricul ture have come however at great cost to the environment and the social fabric costs that are not included in the price of our food economists would call these costs externali ties Low prices at the grocery store give us a false sense that our food comes cheap but they do not include the cost of cleaning up farm pollution for example or the cost of vast government subsidies to agriculture In 1996 the US government spent 687 bil lion on agricultural subsidies which trans lates into 259 per consumer and even more per taxpayer 8 Industrial agriculture s tendency toward larger more mechanized farms has also exacted a social toll Studies have shown that farm consolidation leads to the deterioration of rural communities 9 According to University of California anthropologist Dean MacCannell We have found depressed median family incomes high levels of poverty low education levels social and economic inequality between ethnic groups etc associated with land and capital concentration in agriculture 10 In this paper we first outline the environ mental and public health problems associ ated with our current agricultural system highlighting animal agriculture as a worst case example We then discuss how a sus tainable agriculture can address these issues Impact of Food Production on the Environment Fertilizers In 1998 the world used 137 mil lion metric tons of chemical fertilizers of which US agriculture consumed about 20 million tons or 15 Between 1950 and 1998 worldwide use of fertilizers increased more than 10 fold overall and more than 4 fold per person 1112 Tilman 13 esti mated that crops actually absorb only one third to one half of the nitrogen applied to farmland as fertilizer Nitrogen that runs off croplands into the Mississippi River and its tributaries has been implicated as a major cause of a dead zone in the Gulf of Mexico 14 This zone suffers from hypoxia a dearth of dissolved oxygen lt 2 mgL Excess nutrients fuel algal blooms by speeding up the algae s growth and decay cycle This depletes oxygen in the water killing off immobile bottom dwellers and driving off mobile sea life such as fish and shrimp In 1999 the Gulfs dead zone grew to 20000 km2 about the area of New jersey its largest recorded size 15 Excess nitrogen in soil can lead to less diversity of plant species as well as reduced production of biomass Additionally some ecologists contend that this decrease in diver sity makes the ecosystem more susceptible to drought although this issue has been con troversial 16 Chemical fertilizers can gradually increase the acidity of the soil until it begins to impede plant growth 17 Chemically fertil ized plots also show less biologic activity in the soil food web the microscopic organisms that make up the soil ecosystem than do plots fertilized organically with manure or other biologic sources of fertility 18 Pesticides Each year the world uses about 3 million tons of pesticides comprising her bicides insecticides and fungicides formu lated from about 1600 different chemicals Complete toxicity data are lacking however for most of these substances In the United States insecticide use increased 10 fold between 1945 and 1989 19 Some of the increase in pesticide use can be attributed to monocropping practices which make crops more vulnerable to pests but high volume use also re ects the impre cise nature of pesticide application Cornell entomologist David Pimentel 19 and col leagues stated It has been estimated that only 01 of applied pesticides reach the target pests leaving the bulk of the pesticides 999 to impact the environment That environmental impact can include widespread decline in bird and beneficial insect populations This can disrupt the bal ance between predator and prey because pests often recover faster from pesticide applica tions than do the predators that normally keep pest populations under control 20 Pesticide runoff and airborne pesticide drift pollute surface waters and groundwater Some of the more disturbing ndings on pesticide impact are as follows The number of honeybee colonies on US farmland dropped from 44 million in 1985 to lt 19 million in 1997 in large part due to direct and indirect effects of pesticides Exposure to pesticides can weaken honeybees immune systems making them more vulnerable to natural enemies such as mites and can also dis rupt their reproduction and development 2122 Honeybees are involved in the pollination of at least 10 billion worth of US crops 23 providing farmers with an essential natural service A study in the St Lawrence River Valley in Quebec Canada suggests a link between pesticides and developmental abnormalities in amphibians Among other deformities researchers observed frogs with extra legs growing from their abdomens and backs stumps for hind legs or fused hind legs 24 Other studies suggest that amphibian deformities may be caused by UVB radia tion 25 or parasites 26 0 Pesticide exposures have compromised VOLUME 110 NUMBER 5 I May 2002 Environmental Health Perspectives immune function in dolphins seals and whales 27 Because of the widespread use of pesticides many target species whether insects or plants develop resistance to the chemicals used against them The number of insect species known to display pesticide resistance has increased from lt 20 in 1950 to gt 500 as of 1990 Meanwhile scientists have identi ed 273 plant species that exhibit herbicide resistance 2829 Soil Land degradation and in particu lar the deterioration of soils is one of the most serious challenges facing humankind as it attempts to feed a growing population It takes anywhere from 20 to 1000 years for a centimeter of soil to form 30 yet the United Nations has estimated that wind and water erode 1 of the world s topsoil each year 31 In 1990 Oldman et al 32 estimated that since World War 11 poor farming prac tices had damaged about 550 million hectares an area equivalent to 38 of all farmland in use today More than 30 years ago the US Soil Conservation Service recommended that farmers reduce soil erosion to no more than 5 tons of topsoil per acre per year 33 Between 1982 and 1997 the average erosion rate fell from 73 tons per acre per year to 5 tons 34 Industrial agriculture also endangers soil health because it depends on heavy machin ery that compacts the soil destroying soil structure and killing bene cial organisms in the soil food web 35 Free range cattle can have a positive in u ence on natural ecosystems when they graze in a sustainable fashion The US Department of Agriculture USDA Agricultural Research Service found that moderately grazed land one cow per 16 acres had more biodiversity than did ungrazed or heavily grazed land 36 When animals graze land heavily they can also cause soil erosion by compacting the soil and stripping the land of vegetation that holds soil in place Feedlot cattle and indus trial animal agriculture in general destroy Hectares per person 1951 15155 1970 1915 Reviews Agriculture39s impact on environment and health topsoil because growing grain for this indus try requires so much cropland Land Most of the world s arable land either is in use for agriculture or has been used up by unsustainable agriculture most often because once fertile soil has been degraded or eroded 37 The world s supply of arable land per person has been declining steadily Figure 1 An extreme example of land degradation is the phenomenon known as deserti cation which the United Nations has defined as land degradation in arid semi arid and dry sub humid areas resulting from various fac tors including climatic variations and human activities 38 The annual global cost of deserti cation has been roughly estimated at 423 billion 39 Deserti carion reduces the amount of land available for agriculture Agriculture can contribute directly to deserti cation through poor agricultural practices such as overcultiva tion overgrazing and overuse of water and indirectly when land is deforested to create new cropland or new pastures for livestock According to the Worldwatch Institute almost 20 million kmz or 15 of the all land surface may already be experiencing some degree of deserti cation 40 In the past increasing demand for grain has been met by two means increasing the amount of land used to grow grain and increasing the yields per land unit Both avenues to higher grain production have become more constrained in recent years 41 The discussion of grain supplies some times leaves out the impact of meat produc tion and consumption on these calculations A reduction in meat consumption would help alleviate land scarcity because 37 of the world s grain and 66 of US grain production is fed to livestock 42 Land planted in cereal grains produces 2 10 times as much protein for human con sumption as land devoted to beef produc tion for legumes the ratio is anywhere from 101 to 201 43 Yet in the competition for land in poorer countries the cattle 19311 1985 19311 1995 1999 Figure 1 Average number of hectares of arable land per person worldwide 4 Environmental Health Perspectives VOLUME 110 I NUMBER 5 May 2002 industry sometimes crowds out subsistence farmers who are then forced to grow food on marginal land Often that land is steep and susceptible to erosion when cultivated 44 Water Agriculture affects water resources in two ways irrigating fields using surface waters or aquifers diverts water from other potential uses and when farming practices pollute surface waters and aquifers they reduce the amount of water that is suitable for other uses The US Environmental Protection Agency has blamed current farming practices for 70 of the pollution in the nation s rivers and streams The agency reports that runoff of chemicals silt and animal waste from US farmland has polluted more than 173000 miles of waterways 45 Agriculture accounts for about two thirds of all water use worldwide far exceeding industrial and municipal use 46 Figure 2 In many parts of the world irrigation is depleting underground aquifers faster than they can be recharged In other cases agricul ture depends upon fossil aquifers that mostly contain water from the last ice age These ancient aquifers receive little or no recharge so any agriculture that depends upon them is inherently unsustainable The Ogallala Aquifer covers parts of eight states in the US Midwest and is a crit ical resource for the region s agriculture The aquifer receives little recharge and its water table is dropping as much as 1 myear 30 It has been estimated that in another decade or two the aquifer will be so low that its use for irrigation will become prohibitively expensive 4 Irrigation has been used to turn many low rainfall regions into agricultural won ders at least in the short term Onethird of all the food we grow comes from the one sixth of cropland that is irrigated 33 However excessive irrigation can exact an ecologic price through waterlogging and 23 90 69 Agricultural industrial Municipal Figure 2 Global water use by sector based on 1990 figures Adapted from Postel 46 447 Reviews Horrigan et a1 salinization Irrigation water leaves behind salts that slowly diminish the soil s productiv ity The Food and Agriculture Organization of the United Nations FAO estimates that about 13 of the world s irrigated land is either waterlogged or excessively salty and another 33 is affected to some degree Salinization affects 28 of the irrigated land in the United States and 23 in China for example According to hydrologist Daniel Hillel 33 many of the problems with irrigation arise from careless practices such as overwatering He advocates modern izing the irrigation systems in developing countries where the most acute irrigation problems exist Water use in irrigation is extremely inef ficient the FAO estimates that crops use only 45 of irrigation water 47 In the case of China s Yellow River only 30 of the water extracted for irrigation actually reaches crops Agriculture extracts 92 of the water taken from the river which in 1997 failed to reach the sea for 226 days its worst dry spell ever recorded Since the 19505 the amount of land irrigated with water from the Yellow River has more than tripled 48 In parts of the United States much of the water used for irrigation serves the livestock sector For example the beef feedlots of Colorado Kansas Nebraska and the Texas panhandle get their feed grain from irrigated agriculture that relies on diminishing ground water supplies Beef production requires large volumes of water as much as 100 times that required to produce equivalent amounts of protein energy from grains 49 Energy Converting grain into meat entails a large loss of food energy particu larly if cattle are doing the converting Conservative estimates are that cattle require 7 kg of grain to create 1 kg of beef com pared with about 4 kg for pork and just over 2 kg for chicken 50 Fossil fuel energy is also a major input to industrial agriculture The food production system accounts for 17 of all fossil fuel use in the United States and the average US farm uses 3 kcal of fossil energy in producing 1 kcal of food energy Meat production uses even more energy In the typical feedlot sys tem where a little more than one half of the cattle s feed is grain the fossil energy input is about 35 kcalkcal of beef protein produced 37 In addition the road from the farm to the dinner plate is an energy intensive one because transporting processing and pack aging our food require large amounts of fuel For instance before arriving at the Jessup Maryland Terminal Market vegetable shipments travel on average about 1600 miles and fruit shipments about 2400 miles 448 51 Some estimated energy inputs for pro cessing various foods are 575 kcalkg for canned fruits and vegetables 1815 kcalkg for frozen fruits and vegetables 15675 kcalkg for breakfast cereals and 18591 kcal kg for chocolate 37 A 1969 study by the Department of Defense estimated that the average processed food item produced in the United States travels 1300 miles before it reaches con sumers 52 Processing accounts for about one third of the energy use in the US food system and each calorie of processed food consumes about 1000 calories of energy 52 In all likelihood the food system has become more energy intensive since the time of this study Biodiversity Agriculture is dependent on biodiversity for its existence and at the same time is a threat to biodiversity in its imple mentation One way that agriculture depends on biodiversity is in developing new varieties of plants that keep pace with ever evolving plant diseases When plant breeders need to nd a resistance gene to improve a domestic variety they sometimes crossbreed the variety with a wild relative However because they are under pressure to bring a product to market quickly plant breeders usually search for a sin gle gene that confers resistance This practice is risky as Cary Fowler and Pat Mooney explain in Shattering Food Politics and the Loss of Genetic Diversity 53 Frequently resistance in a traditional landrace wild variety is not nearly so simple as one gene Resistance may be the product of a com plex of genes literally hundreds of genes working together By utilizing onegene resistance the plant breeder gives the pest or disease an easy target It has only to overcome or find a way around that one line of defense The use of one gene for resistance one gene which is routinely overcome by pest or disease results in that gene being used up It no longer provides resistance It may have taken thousands of years for a wild plant to develop its complex of resis tance genes but modern plant breeding methods are chipping away at this natural resource one resistance gene at a time and at a rate beyond nature s ability to replenish it 54 The practice of monocropping or mono culture planting the same crop over a large land area creates greater necessity for quick cure plant breeding Insect pests and plant diseases are both aided by monocrop ping if a crop variety that may be susceptible to a plant disease or insect pest is planted contiguously and in great volume Industrial agriculture erodes biodiversity not only because it favors monocultures but also because those monocultures replace diverse habitats One example is the way rice monocultures crowd out local wild varieties In the Philippines Indonesia and some other developing countries more than 80 of farmers now plant modern rice varieties In Indonesia this led to the recent extinction of 1500 local rice varieties in just 15 years 55 Another threat to biodiversity is the con tinued consolidation of the seed industry and the effect it is having on the availability of nonhybrid plant varieties As of 1998 the 10 largest seed companies controlled 30 of the global market 56 Large seed compa nies tend to rely on rst generation hybrids because they force growers to buy new seed every year As the industry has consolidated traditional varieties have been removed from seed catalogs at an alarming rate In 1981 nearly 5000 nonhybrid vegetable varieties were being sold through mailorder catalogs by 1998 88 of those varieties had been dropped 57 The dependence of industrial agriculture on synthetic chemicals has reduced biodiver sity in the insect world as well Pesticides kill wild bees and other bene cial species that are nontarget victims Managed pollination a 10 billion a year industry in the United States and Canada relies on just two species of bee In contrast North America has 5000 wild bee species but these have mostly disap peared from agricultural lands due primarily to pesticides a lack of oral diversity destruction of habitats and competition with managed pollinators 58 Excessive fertilizer use also reduces biodi versity because of the effect that nitrogen runoff is having on ecosystem balance A minority of species can thrive in high nitrogen environments and these sometimes crowd out all other species in the ecosystem 59 Global warming and climate change Agriculture is directly responsible for about 20 of human generated emissions of green house gases according to estimates by the Intergovernmental Panel on Climate Change Changes in land use contribute about 14 of the total human generated emissions of greenhouse gases and much of this land development is for agricultural purposes 60 Industrial animal production Animals have traditionally played an important role in agriculture not only as a source of food but also as a way to recycle nutrients and build soil organic matter Their manure deposited on croplands or rangelands helps build the fertility of the soil In recent decades however industrial agriculture has increasingly separated ani mals from the land More and more meat production is occurring in produced 14 billion tons of waste in 1997 which is 130 times the nation s volume of human waste or 5 tons of animal waste for every US citizen 6 By concentrating thousands of animals into a small area industrial animal produc tion creates threats to both the environment and human health Despite this the trend in the meat industry has been toward greater concentration of livestock Fewer and fewer farms are raising animals and the average number of animals per farm is going up For example between 1967 and 1997 the number of hog farms in the United States declined from over a million to just 157000 The largest 3 of farms all with at least 1000 hogs each now produce 60 of US hogs 6162 According to Copeland and Zinn 62 the story is similar in poultry and beef output Broiler production nearly tripled between 1969 and 1992 while the number of farms with broiler houses dropped by 35 Firms with more than 100000 broilers accounted for 70 of all sales in 1975 but now account for more than 97 of sales In beef more than 40 of all production comes from 2 of the feedlots 61 Because the huge volume of manure from factory farms cannot be absorbed by local croplands the industry stores it in open pits euphemistically called lagoons by the industry that are prone to spills Animal waste is a major contributor to the excessive nutrient loading that is suspected of causing outbreaks of P esteria piscicida and large sh kills in North Carolina waters and in the Chesapeake Bay in recent years 6163 By concentrating hundreds or thousands of animals into crowded indoor facilities factory farms raise ethical issues about their treatment of animals Each full grown chicken in a factory farm has as little as 06 ft2 of space Crowded together in this way chickens become aggressive toward each other and sometimes even eat one another For this reason factory farms subject them to painful debeaking 64 Hogs too become aggressive in tight quarters and often bite each other s tails In response factory farmers often cut off their tails Concrete or slatted floors allow for easy removal of manure but because they are unnatural surfaces for pigs they result in skeletal deformities of the legs and feet 65 Ammonia and other gases from the manure irritate animals lungs making them suscep tible to pneumonia Researchers from the University of Minnesota found pneumonia like lesions on the lungs of 65 of 34000 hogs they inspected 66 Factory farms chain veal calves around the neck to prevent them from turning around in their narrow stalls Movement is Reviews Agriculture s impact on environment and health discouraged so that the calves muscles will be underdeveloped and their flesh will be tender They are kept in isolation and near or total darkness during their 4 month lives and are fed an ironde cient diet to induce anemia so that their flesh develops the pale color prized in the marketplace 65 Genetically engineered crops Genetically engineered crops have been on the market only since 1996 but already they occupy 130 million acres worldwide including a 19 increase in acreage in 2001 This includes 88 million acres in the United States 67 Transgenic crops have been defined as genetically engineered to contain traits from unrelated organisms In traditional plant breeding a desired trait must be obtained from a closely related species that will breed with that plant through natural mechanisms but genetic engineers can search for the desired trait anywhere in the plant or animal kingdom 68 Introducing genes into crops in this novel way raises ethical environmental and health concerns In this paper we do not dis cuss the ethics of transgenic crops but we review the health issues in Impact of Food Production and Diet on Health below The environmental concerns raised by genetically engineered crops include the following 39 Gene transfer to wild relatives Herbicide resistance genes engineered into crops can spread to wild relatives of those crops The FAO has said this could create super weeds and make weed control more diffi cult 69 Increased herbicide use The most com mon reason for manipulating crop genes is to confer resistance to commercial herbi cides Increased use of genetically engi neered crops of this sort will likely be accompanied by increased use of the rele vant herbicides 69 Weeds would there fore be exposed to more herbicide helping them develop herbicide resistance more rapidly Insect resistance to Bacillus thuringiensis Br toxin The second most popular reason for genetically engineering crops is to give them resistance to insects viruses and fungi Genetic engineers have produced insect resistance in corn rice cotton tobacco and many other crops by intro ducing a gene that produces the Bt toxin In other words the plant gives off its own pesticide so farmers do not need to apply pesticides In nature the soil bacterium B inuringiensis produces the Bt toxin The widespread use of Bt crops would in all likelihood hasten the development of Bt resistance in insects that are currently vul nerable to this natural pest control method Environmental Health Perspectives VOLUME 110 NUMBER 5 I May 2002 This would eliminate an important organic pest control method often used by organic growers as a last resort 68 Bt crops may also pose risks for nontarget species Two recent studies reported that pollen from Bt corn can be deadly for monarch butter y larvae 7071 Impact of Food Production and Diet on Health The preceding section describes the environ mental harms caused by our dominant food production system Industrial food produc tion methods and some of the foods they produce are also causing both acute and chronic disease in humans Among the prob lems are the following Animal based foods contribute to chronic diseases 0 Pesticide residues enter our bodies through air water and food and raise risks for cer tain cancers as well as reproductive and endocrine system disorders Concentrated high speed meat production leads to a greater risk from foodborne pathogens some of them newly emerging Excessive use of antibiotics in animal agri culture may create resistant strains of microbes in humans In this section we discuss many comparison studies of the diets of various population groups and their health outcomesThese epi demiologic studies have methodologic defi ciencies in that most data sources are not sufficiently comprehensive to eliminate the effects of all possible confounding variables during multivariate analysis However in cases where the body of epidemiologic evi dence is substantial andor the disparities are large these comparisons still provide results worthy of our consideration Diet and Disease We have evidence that large quantities of saturated fat in the diet contribute to the chronic degenerative diseases that are the most common causes of death in affluent societies Animal based diets which are high in saturated fat dominate in the West and are on the increase in many developing countries Although undernutrition is still com mon in developing countries affecting about 800 million people worldwide in af uent countries the main causes of death are associated with overnutrition In the United States for example the average adult male consumes 154 of the recom mended daily allowance RDA for protein 97 g vs an RDA of 63 g and the average adult female consumes 127 of the RDA 635 g vs an RDA of 50 g 7273 The average American derives 67 of protein from animal sources compared to a 34 449 Reviews Horrigan et al average worldwide 37 Meanwhile the World Health Organization WHO esti mates that gt 40 of children or 230 mil lion in poor countries are stunted by undernutrition 74 According to the US Surgeon General 75 the preponderance of scienti c evi dence strongly suggests that a dietary pattern that contains excessive intake of foods high in calories fat especially saturated fat cholesterol and sodium but that is low in complex carbohydrates and ber is one that con tributes significantly to the high rates of major chronic diseases among Americans Animal products contain no fiber and almost no complex carbohydrates Animal products are also the only source of choles terol in the diet and they contribute most of the saturated fat in the typical US diet On the other hand vegetarian diets are associ ated with lower rates of chronic disease According to the American Dietetic Association 76 A considerable body of scienti c data suggests positive relationships between vegetarian diets and risk reduction for several chronic degenera tive diseases and conditions including obesity coronary artery disease hypertension diabetes mellitus and some types of cancer Cardiovascular disease Diseases of the circulatory system account for almost one half of all deaths in the developed world according to the WHO 77 Mortality from circulatory system disease has been falling in affluent countries in recent years but it is increasing in newly industrializing countries that are adopting Western diet patterns 77 This increase in diseases of affluence in newly industrializing countries parallels the increasing consumption of animal based foods as well as higher smoking rates and greater urbanization In 1999 the average US citizen con sumed 124 kg 273 pounds of meat By contrast average meat consumption for all industrialized countries is 77 kg person and for all nonindustrialized countries it is 27 Since 1961 US per capita meat consump tion has increased by 40 4 Figure 3 Cardiovascular disease is the leading cause of death in the United States and one of the major risk factors is a high cholesterol level in the blood The human body manu factures all the cholesterol it needs and any cholesterol acquired through diet comes from animal foods because plant foods con tain no cholesterol 78 Consumption of animal foods elevates a person s cholesterol level and this in turn elevates the person s risk for heart attack stroke and arterial disease Whereas the average cholesterol level among heart attack victims is 244 mgdL of blood serum heart attack risk falls to virtually zero when the 450 cholesterol level is less than 150 mgdL 79 As of 1990 the average cholesterol level in the United States was 205 mgdL 78 Vegetarians who avoid meat but con sume dairy products andor eggs have lower cholesterol levels than do omnivores Still lower are cholesterol levels in vegans people who refrain from eating any animal prod ucts One meta analysis found that in nine comparison studies vegans had an average cholesterol level of 158 mgdL vegetarians 182 mgdL and omnivores 193 mgdL 80 Vegetarians also have lowerthanaverage mortality in general and this is attributed mostly to their lower rates of heart disease and certain cancers 80 Cancer Diets that are high in fat and low in ber are associated with an increased risk of colon cancer 81 In addition to being high in fat meat and dairy products contain no ber In contrast many epidemiologic studies have found that high ber intake leads to lower risk of not only colon cancer but also breast and prostate cancer 80 Prostate can cer has been linked to high intakes of calories total fat and milk meat and poultry 82 Lung cancer is also less prevalent in vege tarians even when one controls for the effects of smoking 83 Countries with high rates of fat consump tion have the highest breast and colon cancer mortality whereas the lowest death rates from these diseases occur in populations with the lowest levels of fat consumption 84 Diabetes Seventh Day Adventists are overwhelmingly vegetarian or near vegetar ian so researchers and others often compare their health outcomes with those of the gen eral population One study 80 found that rates of diabetes in Seventh Day Adventists were 45 of rates in all US white adults and that type II noninsulin dependent dia betes correlated positively with obesity and fat and protein intake Vegetarians have lower rates of these risk factors 80 Treatment programs for diabetics now recommend drastic reductions in consump tion of meat dairy products and oils but 140 120 100 kg per capita per year 3 b 90 increased consumption of grains legumes and vegetables Medical costs ofmeat consumption Barnard et a1 85 estimated that meat con sumption costs the United States roughly 3060 billion a year in medical costs The authors made this calculation which they considered a conservative one on the basis of the estimated contribution that eating meat makes to the diseases discussed above plus other chronic diseases common in af u ent countries and foodborne illnesses linked to meat consumption Pesticides and Health Pesticides produce both short and long term effects on human health The United Nations has estimated that about 2 million poisonings and 10000 deaths occur each year from pesticides with about three fourths of these occurring in developing countries 86 The longterm effects of pesticides include elevated cancer risks and disruption of the body s reproductive immune endocrine and nervous systems Population based studies have shown associations between certain types of pesticide and certain cancers Table 1 Pesticides can suppress the immune sys tem In a 1996 report Repetto and Baliga 27 cite epidemiologic evidence of an associa tion between pesticide exposure and increased incidence of human disease particularly those diseases to which immunocompromised indi viduals are especially prone 27 The list of pesticides that are suspected endocrine disruptors includes atrazine and alachlor two of the most commonly applied herbicides on corn and soybean crops in the United States Just over one half of the herbi cides used in the United States in 1991 were applied to corn soybeans or cotton 88 Many pesticides have not been tested for their toxicity and testing in the past has focused on acute effects rather than long term effects In an inventory of commonly used chemicals in 1984 the National Research Council found that data required for Figure 3 Average meat consumption in selected countries in 1999 and averages for all industrialized and developing countries 4 VOLUME 110 NUMBER 5 May 2002 Environmental Health Perspectives complete health hazard evaluations were avail able for only 10 of pesticides 89 Human exposure to pesticides can come through residues in food either on or within fruits and vegetables or in the tissues of sh and animals we eat through conta minated drinking water and through the air we breathe because of pesticide drift from the spraying of elds or lawns Some pesticides accumulate up the food chain or bioaccumulate A 1967 study found that DDT levels were 20000 times higher in one sh species than they were in the surrounding sea water and 520000 times higher in sheating cormorants 90 So when humans eat foods higher on the food chain more meat milk cheese and eggs and fewer plant foods they increase their exposure to bioaccumulated pesticides Industrial Food System and Public Health The production and processing of food are increasingly concentrated fewer owners and larger operations automated and fast paced which has implications for public health Among the major problems Pollution from factory farms is harming the health of both workers and residents living downstream or downwind from these operations New strains of foodborne pathogens eg Listeria and toxigenic Escherichia coli have emerged in recent years and long recog nized pathogens have been causing more widespread harm The nonmedical use of antibiotics in animal agriculture may be threatening the effective ness of antibiotics in treating human disease by creating selective pressure for the emer gence of antibioticresistant bacteria Genetically engineered foods present risks of new allergens in the food supply and may be harmful to immune systems and vital organs 0 These phenomena are due in part to pro duction and processing methods that emphasize economic ef ciency but do not give suf cient priority to public health or the environment Factory farming and human health Gases from animal manure at factory farms create potential human health risks for work ers and residents living downwind and Reviews Agriculture s impact on environment and health manure runoff can damage local water qual ity by overloading it with nutrients particu larly phosphates Factory farms store manure from animal con nement buildings either in pits under neath the buildings or in nearby open air pits often extending over several acres Farmers and farm workers have died from asphyxiation after entering underground pits used for storing animal manure 91 The prevalence of occupational respira tory diseases occupational asthma acute and chronic bronchitis organic dust toxic syndrome in factory farm workers can be as high as 30 92 A University of Iowa study found that people living near large scale hog facilities reported elevated inci dence of headaches respiratory problems eye irritation nausea weakness and chest tightness 93 Manure runoff from factory farms is among the suspected causes of outbreaks of P esteria piscicia a in Maryland Virginia and North Carolina The human health effects have included acute short term memory loss cognitive impairment asthmalike symptoms liver and kidney dysfunction blurred vision and vomiting 94 Water polluted with manure runoff has other health implications A Senate report 61 noted that Manure contains pathogens to which humans are vulnerable including Salmonella and Cryptosporidium and can pollute drinking water with nitrates potentially fatal to infants More indirectly microbes that are toxic to animals and people are thought to thrive in waters that have excessively high levels of nutrients from sources including animal waste pollution Foodhorne pathogens The US Centers for Disease Control and Prevention CDC have estimated that foodborne diseases cause approximately 76 million illnesses 325000 hospitalizations and 5000 deaths in the United States each year Of the approxi mately 1800 deaths attributed to known pathogens more than 75 are blamed on Salmonella Listeria and Toxoplasma 95 All three pathogens are transmitted to humans primarily through meat Two bacteria commonly found on meat Campylohacter and Salmonella cause more than 3 million foodborne illnesses in the United States each year 95 These bacteria Table 1 Associations between various classes of pesticide and various forms of cancer Class of pesticide Cancer Phenoxyacetic acid herbicides Organochlorine insecticides NonHodgkin39s lymphoma soft tissue sarcoma prostate Leukemia nonHodgkin s lymphoma soft tissue sarcoma pancreas lung breast Organophosphate insecticides NonHodgkin s lymphoma leukemia Arsenical insecticides Lung skin Triazine herbicides Ovary Data from Blair and Zahm 87 Environmental Health Perspectives VOLUME110lNUMBER5lMay 2002 occur naturally on chickens and are not always harmful to them but in humans they can cause severe diarrhea and nausea and occasionally produce fatal disease The crowded conditions of factory farms increase the level of contamination and the high speed automated methods of slaughtering and processing the animals make it dif cult to detect that contamination Much less common but more deadly than the bacteria mentioned above are the newly emerging strains of toxigenic E coli and Listeria The CDC puts the annual dis ease burden for E coli at about 62000 ill nesses and 50 deaths and blames Listeria for about 2500 illnesses and 500 deaths 95 Infection with the enterohemorrhagic strain of E coli 01572H7 was rst discov ered in 1975 The pathogen causes bloody diarrhea and acute renal failure and is some times fatal children and the elderly are at greatest risk E coli 0157zH7 is most often spread by undercooked ground beef or raw milk 96 Listeria monocytogenes is referred to as an emerging pathogen because only recently has food been recognized to play a role in its spread According to the US Food and Drug Administration infections with Listeria can cause abortion and stillbirth and blood poi soning or meningitis in infants and immune deficient persons Listeria is most often associated with consumption of certain dairy products and processed meats 97 Another newly emerging concern about the food supply is a neurologic disease in cat tle known as bovine spongiform encephalopa thy BSE According to the WHO 98 a new variant of Creutzfeldt Jakob disease a degenerative neurologic disease in humans has a strong link to exposure to BSE proba bly through the food supply BSE was rst recognized in cattle in 1986 and epidemio logic studies suggest that cattle feed prepared from carcasses of dead ruminants was the source of the disease 98 Antihiotics in animal agriculture Seventy percent of US produced antibiotics are fed to animals to promote growth 99 Excessive use of such drugs in animals can enhance the development of drug resistant strains of disease which can then be trans mitted to humans through the food supply The National Research Council and Institute of Medicine 100 have noted that there is a link between the use of antibiotics in food ani mals the development of bacterial resistance to these drugs and human diseases although the incidence of such disease is very low The WHO has called for reduced use of antibiotics in animal agriculture noting that resistant strains of Salmonella Campylohacter 451 Reviews Horquan et al Enterococci and E coli have been transmitted from animals to humans 101 Genetically engineered atls Only recently have genetically engineered foods been intro duced into the human food supply One of the concerns surrounding genetic engineering of foods is that new allergens could be introduced into the food supply because the sources for genetically engineered material may include organisms not previously eaten by humans 102 In addition it will be harder for people with food allergies to avoid consuming an offending food if proteins from that food are integrated into a food to which they are not allergic For example soybeans that were genet ically engineered to contain proteins from Brazil nuts caused reactions in individuals who were allergic to Brazil nuts 103 Antibiotic resistance genes are used as markers in the genetic engineering of foods This practice raises two possible concerns eating such foods soon after taking antibi otics could reduce or eliminate the drugs effectiveness because enzymes produced by the resistance genes can break down antibi otics and resistance could be transferred to disease organisms in the digestive tract mak ing it harder to treat them with antibiotics But there is disagreement over these issues within the scienti c community and more research is under way 104105 Sustainable Agriculture Unsustainability in agriculture is not a new issue Large civilizations have risen on the strength of their agriculture and subse quently collapsed because their farming methods had eroded the natural resource base 106 Today s conventional or indus trial agriculture is considered unsustainable because it is similarly eroding natural resources faster than the environment can regenerate them and because it depends heavily on resources that are nonrenewable eg fossil fuels and fossil aquifers One of the goals of the sustainable agricul ture movement is to create farming systems that mitigate or eliminate environmental harms associated with industrial agriculture Sustainable agriculture is part of a larger move ment toward sustainable development which recognizes that natural resources are nite acknowledges limits on economic growth and encourages equity in resource allocation Sustainable agriculture gives due consider ation to longterm interests eg preserving topsoil biodiversity and rural communities rather than only shortterm interests such as pro t Sustainable agriculture is also place speci c For example a farming system that is sustainable in a highrainfall area may not be sustainable in an arid climate Sustainable agriculture is dynamic meaning that it must evolve to respond to changes in its physical 452 environment or its social or economic con text Sustainable agriculture is holistic in that it takes a systemwide approach to solving farm management problems and also because it places farming within a social context and within the context of the entire food system Sustainable agriculture has been de ned in several ways for example Sustainable agriculture integrates three main goals environmental health economic prof itability and social and economic equity Sustainability rests on the principle that we must meet the needs of the present without compro mising the ability of future generations to meet their own needs 107 Sustainable agriculture is a model of social and economic organization based on an equitable and participatory vision of development which recognizes the environment and natural resources as the foundation of economic activity Agriculture is sustainable when it is ecologically sound economically viable socially just cultur ally appropriate and based on a holistic scienti c approach 108 0 Sustainable agriculture does not refer to a prescribed set of practices Instead it challenges producers to think about the longterm implica tions of practices and the broad interactions and dynamics of agricultural systems It also invites consumers to get more involved in agriculture by learning more about and becoming active partici pants in their food systems A key goal is to understand agriculture from an ecological per spective in terms of nutrient and energy dynamics and interactions among plants ani mals insects and other organisms in agroecosys tems then balance it with pro t community and consumer needs 109 Sustainable methods Although no one set of farming practices constitutes sustain able agriculture we brie y describe here cer tain methods that enhance sustainability Crop rotation By rotating two or more crops in a field farmers interrupt pests reproductive cycles and reduce the need for pest control 110 Rotations sometimes reduce the need for added fertilizer because one crop provides nutrients for the next crop 0 Cover crops Cover crops are planted to improve soil quality prevent soil erosion and minimize weed growth Some cover crops can also generate income No till and lowtill farming These farm ing systems are based on the premise that minimizing disturbances to the soil will increase the retention of water nutrients and the topsoil itself Between 1980 and 1993 the amount of land under conserva tion tillage increased from lt 15 to about 35 of all US farmland 111 Soil management Good stewardship of the soil involves managing its chemical biologic and physical properties Industrial agriculture has tended to emphasize the chemical properties of soil to the detriment of the other two An acre of healthy soil can contain 4 tons of organisms which make up the soil s ecosystem 112 Organic matter and compost are food for bene cial bacteria fungi nematodes and protozoa If managed properly these soil organisms perform vital functions that aid in plant growth 113 Healthy soil pro duces plants that are more vigorous and therefore less susceptible to pests Diversity Growing a variety of crops pro vides a buffer against both ecologic and eco nomic problems Monocultures are more vulnerable to pests as well as to uctuations in market price Crop variety can also create more niches for bene cial insects 107 Nutrient management After monitoring the soil content of nitrogen and other nutrients farmers can prevent runoff into adjacent waters and also save money on purchased fertilizers by applying only what the plants and soil can absorb with no excess Integrated pest management An integrated pest management IPM system prefers bio logic methods and uses least toxic chemi cal pesticides only as a last resort To keep destructive insects under control an IPM emphasizes crop rotations intercropping and other methods of disrupting pest cycles as well as plant varieties that have high resis tance to pests IPM also uses insect preda tors as well as biopesticides such as Bt 114 As of 1994 coordinators of the fed eral IPM program were reporting that more than 40000 farmers in 32 states have made signi cant reductions in their use of synthetic chemical pesticides by implementing practices associated with sustainable agriculture 1 15 Rotational grazing By continually moving animals to different grazing areas rota tional grazing prevents soil erosion by maintaining suf cient vegetative cover It also saves on feed costs averts the manure buildup of concentrated animal feeding operations and contributes to soil fertility Barriers to sustainability If our current agricultural system is so harmful and unsus tainable why is it being perpetuated Most important powerful economic interests ben efit from the status quo in agriculture Industrial agriculture relies heavily on exter nal inputs eg synthetic chemical fertilizers and pesticides machinery fossil fuels which mean costs for farmers but pro ts for farm input industries Fa fastest However each new round of cost cutting technology has resulted in increased production and lower prices erasing initial pro tability Thus the quest for greater yields has landed farmers on a technologic treadmill of increas ing inputs and decreasing pro t margins Increasing dependence on off farm resources and distant markets has caused much of the pro tability of agriculture to shift from the farmer to the industries that supply the inputs and market the outputs Madden and Chaplowe 108 estimate that between 1910 and 1990 the share of the US agricultural economy going to farmers declined from 41 to 9 while the mar keting and farm input industries shares increased by similar amounts 108 As farmers pro t margins shrink some farmers choose to enlarge their operations to compensate Invariably this means some farmers get pushed out of business For example in the hog industry about one fourth of all US producers went out of business between 1998 and 2000 17 leaving only 50 producers controlling one half of all hog production 118 The trend toward large scale farming has implications for the economic health of rural communities Studies have shown that inde pendent hog farmers produce more jobs more local retail spending and more local per capita income than do larger corporate operations 62 Pro ts generated by small scale producers of hogs or any other com modity are more likely to remain in the community and create multiplier effects in the local economy Despite these bene ts of small farms US agricultural subsidies flow dispropor tionately to large farms The International Institute for Sustainable Development 8 based in Winnipeg Canada reports that Almost 30 of subsidies go to the top 2 and over four fths to the top 30 Ironically if the United States government were to shift its target from the top 30 to the bottom 70 of farm ers it could save at least 8 billion a year while supplying a competitive boost to lowerincome farms Government subsidies often help perpetu ate unsustainable practices For example one of the largest bene ciaries of federal agricul tural subsidies are the cattle ranchers whose animals graze on federal lands for less than one third the price they would pay on private land Total subsidies in the federal grazing program cost taxpayers at least 500 million a year not counting the cost of the environ mental degradation caused by overgrazing 8 Subsidies often stimulate greater use of chemical inputs despite their environmen tal and public health harms Rice farmers in Japan Taiwan and Korea use just over Reviews Agriculture s impact on environment and health one half of all insecticides applied to rice worldwide yet produce only 2 of the world s crops The reason is that large gov ernment price supports 13 billion worth in Japan make it pro table to increase insecti cide use even when the resulting production gains are small 119 Besides encouraging harmful practices farm subsidy programs often fail to reward good stewardship They tend to emphasize a handful of major crops and put resource conserving crop rotations at a nancial dis advantage 120 Farmers receive no government incentives for sustainable prac tices such as growing clover or alfalfa to enhance soil fertility 120 Governments also help perpetuate chem ical intensive agriculture by funding research on chemical xes for agricultural problems to the exclusion of research on more sustain able options Of 30000 agricultural research projects on the USDA s Current Research Information System for 1995 only 34 had a strong organic focus 2 Adopting sustainable metrods Government programs research and other factors can in uence moves toward sustain ability in agriculture but ultimately this shift also involves decisions by individual farmers Some farmers will be motivated to change because of environmental concerns but we also need to reassure farmers that sus tainable methods are economically viable Comparisons between conventional indus trial and sustainable agriculture systems can be complicated but those that exist describe sustainable practices as highly productive and economically competitive 110 In the early 19905 the Gallo Wine Company Sonoma County CA shifted 6000 acres of wine grapes from conventional to organic methods After a transition phase during which production was more expen sive Gallo was producing yieldsequivalent to those produced by its previous chemical methods but at a lower cost per acre 115 Sustainable systems are especially apt to compare favorably with conventional sys tems when the comparison includes a full cost accounting of the environmental and public health harms and bene ts of each system For example if a conventional sys tem were to produce higher yields per acre than a sustainable one but also degrade local water supplies because of pesticide or fertil izer runoff the bene ts of the higher yield may be offset by the cost of environmental cleanup costs that are usually external ized meaning they are paid by society rather than the polluter Other factors that in uence adoption of sustainable practices are land ownership and the age of the farmer According to an FAO report 122 Environmental Health Perspectives VOLUME 110 l NUMBER 5 May 2002 Land tenure is critical to the adoption of organic free of synthetic chemicals agriculture It is highly unlikely that tenant farmers would invest the necessary labour and sustain the dif cult conversion period without some guarantee of access to the land in later years when the bene ts of organic production are attainable Urban agriculture The world is becom ing increasingly urbanized The United Nations has estimated that world population will increase by about 2 billion people in the next 30 years and all of that growth is expected to occur in urban areas population growth plus continued migration to cities 123 This makes urban agriculture an increasingly important component of agri cultural sustainability Because it produces closer to consumers urban agriculture reduces energy costs and pollution from transport and storage and reduces packaging and spoilage It also offers a viable use for urban waste such as waste water for irrigation creates economic devel opment and improves food security in poor communities 124 Alternative marketing Farmers can cap ture more of the pro tability of agriculture through valueadded products or direct mar keting strategies such as farmers markets and communitysupported agriculture CSA In the CSA model consumers purchase a share in a farm and receive a portion of its harvest This gives farmers more working capital at the beginning of the growing sea son and a guaranteed market at the end Consumers develop a direct link to their food supply and have input into production deci sions CSAs have helped keep many small farms in business 125 Meanwhile farmers markets have enjoyed rapid growth in the United States Between 1994 and 2000 the number of US farmers markets increased by 63 from 1755 to 2863 126 Conclusion Hunger and food insecurity are currently problems not of resource scarcity but of insuf cient political will or moral imperative to change the way food is allocated Pinstrup Anderson et al have estimated that the developing world alone is producing enough food to provide every person with gt 2500 caloriesday 127 If unsustainable agriculture remains the norm however scarcity of resources could soon become a major factor in food insecurity Coupled with energy and resource intensive food production methods rising population and rising per capita consump tion are bringing us closer to the limits of the planet s ability to produce food and ber for everyone The world s sheries may be Reviews Horrigan et al world s 15 most important shing areas and 70 of the major sh species are either fully or overexploited 128 The United Nations most recent midrange projection is that the world popu lation will increase to 93 billion by 2050 129 The world s population is rapidly becoming more urbanized In 1975 about one third of the world s people lived in cities 130 by 2030 that gure is expected to rise to gt 60 131 Both population growth and urbanization bode ill for the environ ment and the social order that it upholds To meet their need for food and other goods the additional people will make fur ther demands upon finite resources such as arable land fertile soil and freshwater When people move from rural to urban areas they characteristically increase their consumption including the amount of ani mal products they consume Thus the com bination of more people and greater consumption per capita are creating a threat of future scarcity in vital resources These problems are complex and have no single solution which leaves many people feeling powerless to affect them One personal act that can have a profound impact on these issues is reducing meat con sumption To produce 1 pound of feedlot beef requires about 2400 gallons of water and 7 pounds of grain 42 Considering that the average American consumes 97 pounds of beef and 273 pounds of meat in all each year even modest reductions in meat consumption in such a culture would substantially reduce the burden on our natural resources For the United States and other industri alized nations lowered meat consumption would yield signi cant public health bene ts particularly a reduction in heart disease sev eral cancers and other chronic diseases These diseases are largely associated with the exces sive fat and protein intakes that are character istic of animal based diets Coupled with sedentary lifestyles excess meat consumption also contributes to the epidemic of obesity Public policies that encourage a shift toward a more plant based diet could bolster individual actions in this area These policies should include preventing factory farms from polluting and requiring them to pay cleanup costs when they do pollute Without such policies the products of factory farms will continue to be arti cially cheap in that prices will not reflect their impact on the environment human health animal welfare or the economic and social stability of rural communities Both the individual and collective actions described above would hasten the shift toward a more sustainable agriculture which is an important component in the larger transition to a sustainable economy 454 Sustainable agriculture is not merely a package of prescribed methods More important it is a change in mindset whereby agriculture acknowledges its dependence on a nite natural resource base including the nite quality of fossil fuel energy that is now a critical component of conventional farm ing systems It also recognizes that farm management problems weeds insects etc cannot be dealt with in isolation but must be seen as part of a whole ecosystem whose bal ance must be maintained In this paper we have introduced some of the environmental and human health problems inherent in industrial agriculture In many respects industrial style meat pro duction provides a worst case example of these problems It also provides an opportu nity for dramatic improvements in environ mental stewardship and public health Because meat consumption is such a major component in the broader issues described here its reduction through both individual and collective action can have profound effects on the health of humans animals and the environment REFERENCES AND NOTES 1 Union of Concerned Scientists Industrial Agriculture Features and Policy Available 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Robert S Lawrence Polly Walker Environmental Health Perspectives Vol 110 No 5 May 2002 pp 445456 Stable URL httplinksjstororgsicisici0091676528200205291103A53C4453AHSACAT3E20CO3B21 This article references the following linked citations If you are trying to access articles from an o campus location you may be required to first logon via your library web site to access JS T OR Please visit your library39s website or contact a librarian to learn about options for remote access to JS T OR References and Notes lA Nutrient Changes in the Mississippi River and System Responses on the Adjacent Continental Shelf Nancy N Rabalais R Eugene Turner Dubravko Justi Quay Dortch William J Wiseman J r Barun K Sen Gupta Estuaries Vol 19 No 2 Part B Dedicated Issue Nutrients in Coastal Waters Jun 1996 pp 3 86407 Stable URL httplinksjstororgsicisici016083472819960629193A23C3863ANCITMR3E20CO3B2V 25Ambient UVB Radiation Causes Deformities in Amphibian Embryos Andrew R Blaustein Joseph M Kiesecker Douglas P Chivers Robert G Anthony Proceedings of the National Academy of Sciences of the United States of America Vol 94 No 25 Dec 9 1997 pp 1373513737 Stable URL httplinksjstororgsicisici00278424281997120929943A253C137353AAURCDI3E20CO3B223 49 Water Resources Agriculture the Environment and Society David Pimentel James Houser Erika Preiss Omar White Hope Fang Leslie Mesnick Troy Barsky Stephanie Tariche Jerrod Schreck Sharon Alpert BioScience Vol 47 No 2 Feb 1997 pp 97106 Stable URL WW NOTE The reference numbering from the original has been maintained in this citation list


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