Implications of leading crop production practices on environmental quality and human health

14 Pages·2015·1.55 MB·English

Implications of leading crop production
practices on environmental quality and
human health
Authors: Theophilus K. Udeigwe, Jasper M. Teboh, Peter N. Eze,
M. Hashem Stietiya, Vipan Kumar, James Hendrix, Henry J.
Mascagni Jr., Teng Ying, & Tarek Kandakji
NOTICE: this is the author’s version of a work that was accepted for publication in Journal of
Environmental Management. Changes resulting from the publishing process, such as peer
review, editing, corrections, structural formatting, and other quality control mechanisms may not
be reflected in this document. Changes may have been made to this work since it was submitted
for publication. A definitive version was subsequently published in Journal of Environmental
Management, [VOL# 151, (March 15, 2015)] DOI# 10.1016/j.jenvman.2014.11.024
Udeigwe, Theophilus K., Jasper M. Teboh, Peter N. Eze, M. Hashem Stietiya, Vipan Kumar,
James Hendrix, Henry J. Mascagni, Teng Ying, and Tarek Kandakji. “Implications of Leading
Crop Production Practices on Environmental Quality and Human Health.” Journal of
Environmental Management 151 (March 2015): 267–279.
doi: 10.1016/j.jenvman.2014.11.024.
Made available through Montana State University’s ScholarWorks
scholarworks.montana.edu
Implications of leading crop production practices
on environmental quality and human health
Theophilus K. Udeigwe a, Jasper M. Teboh b, Peter N. Eze c, M. Hashem Stietiya d,
Vipan Kumar e, James Hendrix f, Henry J. Mascagni Jr. f, Teng Ying g, Tarek Kandakji a
aDepartmentofPlantandSoilScience,TexasTechUniversity,Lubbock,TX79409,USA
bCarringtonResearchExtensionCenter,NorthDakotaStateUniversity,Carrington,ND,USA
cSchoolofGeography&EnvironmentalStudies,UniversityoftheWitwatersrand,WITS2050Johannesburg,SouthAfrica
dDepartmentofLand,WaterandEnvironment,FacultyofAgriculture,TheUniversityofJordan,Amman11942,Jordan
eDepartmentofPlantSciencesandPlantPathology,MontanaStateUniversity,119PlantBioscienceBuilding,Bozeman,MT59717-3150,USA
fNortheastRegion,LouisianaStateUniversityAgriculturalCenter,212-BMaconRidgeRoad,WinnsboroLA71295,USA
gKeyLaboratoryofSoilEnvironmentandPollutionRemediation,InstituteofSoilScience,ChineseAcademyofSciences,Nanjing210008,China
Abstract

Globally,muchweightiscurrentlybeingplacedonagriculturetoprovidefoodforthegrowingpopu-

lationaswellasfeedstockforthebioenergyindustry.Unfortunately,theintensificationof

agriculturaloperationstosatisfythesegrowingneedshasbeenassociatedwithanumberof

environmentalandhumanhealthrisks.Areviewofpublicationsonthesubjectwasconductedand

emphasiswasplacedonarticlesfocusingonagriculture,environment,andpublichealthaswellas

theirinteractions.Supportinginformationwasalsogatheredfrompublicationsofvarious

agriculturalandenvironmentalagencies.Agriculturalpracticeswithpotentialnegativeimplications

ontheenvironmentandhumanhealthwereidentifiedbroadlyas:(a)utilizationofbiosolidsand

animalmanures,(b)useofagriculturalchemicals,(c)managementofpost-harvestresidue,(d)

irrigation,and(e)tillageoperations.Soil,water,andaircontaminationbynutrients,heavymetals,

pathogens,andpesticides,aswellasaircontaminationbyparticulatematters,noxiousgases,and

pathogenswereamongtheleadingenvironmentalimpacts.Someofthehuman-healthimpacts

identifiedincludedneurologicalandreproductivedefects,cardiovascularrisks,cancersandother

diseases(ofkidney,liver,lung,andskin),skinallergies,gastroenteritis,andmethemoglobinemia.

Continualawarenessontheimpactsofthereviewedagriculturalpracticesonenvironmentalquality

andhumanhealthandtheimplementationofexperimentally-backedbestmanagementpracticesin

agriculturalsystemsremainindispensable.
1. Introduction settings,managementpracticesareoftenevaluatedbasedontheir
economicbenefitswithlessattentiongiventotheenvironmental
Environmental quality and human health are issues of global and public health perspectives. Attempts at addressing such
concern,particularlyinthiseraofrapidindustrialization,intense shortcomings surely warrant an understanding of producers'
agriculturaloperations,andclimatechange.Ofinterest,thequest preferences for any given crop and soil management approach
for alternative energy sources has led to the intensification of sincestudieshaveshownthatproducersaremotivatedbyacom-
agriculturaloperationstooffsetthedemandonenergycropssuch binationoffinancial,environmental,andpersonalincentives(Ecker
assugarcane,corn,andsoybean,thus,deepeningtheadverseim- et al., 2012). In the Unites States (US), efforts are being made by
pactsofagriculturalactivitiesonclimatechangeandhumanhealth federal agencies such as the United States Environmental Protec-
(Alcamoetal.,2005;DeFraitureetal.,2008).Inmostagricultural tionAgency(USEPA)andUnitedStatesDepartmentofAgriculture
(USDA)aswellastheirstatecounterparts,tocreateawarenessof
theimplicationsofagriculturalactivitiesonenvironmentalquality
(USEPA, 2005; Elrashidi et al., 2010). Likewise, the World Health
Organization (WHO) has also identified critical links between
agricultureandhumanhealth(HawkesandRuel,2006).However, disposal;likewise,incinerationofbiosolidshasalsodecreasedsince
current data and future projections suggest the need for imple- manyincineratorsareunabletomeettheUSEPA503regulationsof
mentationofbestmanagementpracticesinagriculturalsystemsto theCleanAirAct(Epstein,2002).InEurope,about2.39(cid:1)106tons
curb the environmental degradation and human health risks of dry biosolids which is equivalent to 37% of the total amount
associated with modern-dayagriculture (Alcamo et al., 2005; De producedarereportedlylandappliedannually(Changetal.,2002).
Fraitureetal.,2008;Costelloetal.,2009). Itisreportedthatbiosolidsproductionisconsiderablymoreofan
Avarietyofpollutantsdischargedfromagriculturalsourcesare issue in Europe considering the amount of sludge produced to
notably associated with environmental pollution (USEPA, 2003; agriculturalareaavailableforbeneficialuse(Iranpouretal.,2004),
Gerbaand Smith, 2005). Commonly documented pollutants from thus, suggesting potential future environmental problems. Simi-
agriculturalsourcesincludenutrients,tracemetals,organiccarbon larly,livestockproductionintheUSgeneratesoverabilliontonsof
(OC),pesticidecompounds,noxiousgases,andpathogens(USEPA, manure annually (USEPA, 2011), some of which are injected or
2005;GerbaandSmith,2005;Menzietal.,2010).Certainagricul- surfaceappliedandincorporation.
tural practices such as the application of organic amendments The use of biosolids and animal manures as soil amendments
(animal manures and biosolids), inorganic fertilizers, and pesti- has often been associated with environmental contamination.
cides; crop residue handling;andirrigationwater usehave often Biosolidsandmanurescontainconsiderablequantitiesofnitrogen
beencitedassourcesaswellasfacilitatorsofthetransportofthe (N), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na),
aforementionedpollutantswithintheenvironment(USEPA,2003; andphosphorous(P),aswellasOC(Powers,2004;Sullivanetal.,
Udeigweetal.,2010). 2006;Udeigweetal.,2009;StietiyaandWang,2011).Thedevas-
Varioushealth-relatedissuesinhumanshavealsobeenattrib- tatingimpactofthedirectrunoffofnutrients,particularlyPandN,
utedtoanumberofagriculturalpollutants.Forinstance,linkages from land applied and stored manures and biosolids on surface
betweencancerandcertainagriculturalpesticides(Alavanjaetal., waterquality have also been cited (Rostagno and Sosebee, 2001;
2003) and between respiratory diseases and particulate matters Hoorman et al., 2008). Biosolids and manures have also been
(PM2.5 and PM10) (Arbex et al., 2007), have been widely docu- citedasmajorsourcesoftracemetals(e.g.copper(Cu),zinc(Zn),
mented. Likewise, a number of human health issues relating to lead (Pb), cadmium (Cd), nickel (Ni)) (Iranpour et al., 2004;
trace element ingestion have been noted (Uriu-Adams and Keen, Schroder et al., 2008) (Table 1), and harmful pathogens (e.g.
2005; Boxall et al., 2009). Pathogens present in animal manure Campylobacterspp,Salmonellaspp,Escherichiacoli,Cryptosporidim
and biosolids have been shown to cause a number of health parvum, etc) (Gerba and Smith, 2005; Sidhu and Toze, 2009) ad-
problemsin humans (Mathis etal., 2005; SidhuandToze,2009), ditionstosoilandwater.Directdischargeofgasessuchasmethane
whileenvironmentalcontaminationbynutrientsfromagricultural (CH4),ammonia(NH3),hydrogensulfide(H2S),andcarbondioxide
sources has also been tied to health risks in humans (Fawell and (CO2) from stored and applied biosolids and manures (Chadwick
Nieuwenhuijsen,2003;Kalantar-Zadehetal.,2010).Currentfind- et al., 2011; USEPA, 2011) especially manure stored in deep
ings have also highlighted the relationships between human (anaerobic)butexposedlagoons,hasalsobeennotedforitsenvi-
exposure to agricultural contaminants and climate change; pro- ronmentalandhealthimplications.
jecting that the risks of these contaminants to humans could in-
creaseconsiderablyinthefuture(Boxalletal.,2009). 2.2. Useofagriculturalchemicals
Theintensificationofagriculturalpracticestoprovidefeedstock
forthebiofuel/biodieselindustryandfoodforthegrowingworld Commercial crop production is highly dependent on the utili-
populationfurtherdeepenstheaforementionedchallenges.Thus, zationofagriculturalpesticides(i.e.,anychemicalappliedtocon-
theaimofthispaperwastohighlightcurrentperspectivesonthe trol weeds, insects, plant disease, and rodents). It was estimated
impacts of key crop production practices on both environmental thatover11.5 billionkgof pesticideactiveingredients (valued at
qualityandhumanhealth.Thefirstpartofthisworkwilldiscuss $39.4billion)wereusedworldwidein2007,withover2.5billionkg
the key crop production practices of environmental and human (~$12.5billion)usedintheUSalone(Grubeetal.,2011).IntheUS,
health concerns, followed by a description of the principal con- the agricultural sector accounts for over 70% of all conventional
taminants from agricultural sources, and their impacts on the pesticideused. Estimates ofpesticide usedbytheUS agricultural
environmentandhumanhealth.
2. Principalcropproductionpracticesofenvironmentaland
humanconcern Table1
Levelsoftraceelementsthatoccurasimpuritiesincommonfertilizersaddedto
2.1. Biosolidsandanimalmanureutilization agriculturalsoils.a
Source
Biosolids (aerobically and/or anaerobically digested sewage
Nfertilizer Pfertilizer Manure Sewagesludge
sludge) and manure are historically used on agricultural soils as
mgkg(cid:3)1
sourcesofplantnutrients,withagrowinguseofsolidmanuresas
amendmentstoincreasesoilorganicmatter(SOM)contentespe- As 2e120 1e1200 3e25 2e30
Cd 0.05e8.5 0.1e190 0.1e0.8 <1e3400
ciallyonlightsoilsanddegradedlandscapes(Kimetuetal.,2008).
Cr 3.2e19 66e245 1.1e55 8e41000
Biosolids,aby-productofmunicipalwastewatertreatmentplants, Cu e 1e300 2e172 50e8000
ischaracterizedasacomplexmixtureofOM(USEPA,1999);while Hg 0.3e3 0.01e2 0.01e0.4 <1e55
animal manures are solid and liquid animal wastes that may be Mo 1e7 0.1e60 0.05e3 1e40
treated (by composting, aerobic or anaerobic digestion, or solid Ni 7e34 7e38 2e30 6e5300
Pb 2e27 4e1000 11e27 30e3600
separation)oruntreatedbeforeuse.IntheUSalone,itisestimated Se e 0.5e25 0.2e24 1e10
that8(cid:1)106tonsofdrybiosolidsareproducedannuallyandabout U e 20e300 e <2e5
halfofthesearelandapplied(USEPA,1999;Iranpouretal.,2004). V e 2e160 e e
Land application of biosolids has increased over the years since Zn 15e570 50e1450 15e570 90e50000
many states now have more stringent laws governing landfill a AdaptedfromSelinus,2013.

2.3. Cropresiduemanagement agricultural fields which is highly undesirable because of the
associated impacts on receiving waterbodies (Westermann et al.,
Management of pre-planting and post-harvest residues is a 2001). Surface runoff often carries sediments (or suspended
criticalaspectofmostcropproductionsystems.Thetypeofresidue solids),pesticides,pathogens,nutrients,dissolvedsalts,andmetals
management practices employed can have significant impact on into surface and groundwater sinks which could impact the
environmentalquality,cropyield,andthesubsequentutilizationof biodiversity of aquatic species as well as reduce the recreational
land resources (Cheesman, 2004; Graham et al., 2007). In most values of impacted waterbodies (Beman et al., 2005). Saline and
agricultural settings, residues resulting from the production of metal-contaminatedwaterusedforirrigationcouldovertimelead
crops are generally retained on the soil surface (as in no-till), to the accumulation of the associated pollutants in soils, thereby
plowed in (as in conventional tillage), or burnt. In regions with impactingcropproductivityaswellasinducinglanddegradation
relaxed environmental regulations, burning of residues is often (Wahla and Kirkham, 2008; Wiedenfeld, 2008). Likewise, the
preferredbyproducersbecauseoftheimmediateimpactonfarm increasingcontaminantlevelsindecliningaquifersasevidencedin
operations,diseaseandweedmanagement,andyield(McCartyand somesemi-arid/aridregionsoftheUSsuchastheSouthernHigh
Hartmann,2010). Plains (Scanlon et al., 2005) are also reflecting in the soils of
Burningofcropresiduesispracticedinall50statesintheUS groundwater-irrigated fields (Udeigwe et al., 2015). Incidences of
(McCartyetal.,2009a).Usingsatellitemonitoring,itwasestimated accumulationoftoxicelementsandcompoundsincropshavealso
that over 1.2 million ha of croplands are burnt annually in the been traced to contaminated irrigationwater (Arora et al., 2008;
contiguousUnitedStateswiththemostcroplandburningrecorded Dahaletal.,2008).
in Florida (sugarcane), Arkansas (wheat, corn, soybean), Idaho
(wheat), California (rice, cotton, wheat, and orchard), and Texas 2.5. Tillagesystemsandoperations
(sugarcane)(McCartyetal.,2009b).WithinthecontinentalUS,crop
residueburningisprojectedtoemit6.1TgofCO2,8.9GgofCH4, Various landuse practices, particularly those involving heavy
232.4 Gg of carbon monoxide (CO), 10.6 Gg of nitrogen dioxide machineryoperationshavebeenassociatedwithsignificantsurface
(NO2), 4.4 Gg of sulfur dioxide (SO2), as well as 28.5 Gg of PM10 soilalterationsthateventuallyimpactsoilquality,cropproductivity
(particulatematteroflessthan10mmindiameter),and20.9Ggof (HamzaandAnderson,2005),aswellaswaterqualityandquantity
PM2.5 (particulate matter of less 2.5 mm in diameter) annually (Fleige and Horn, 2000; McVay et al., 2006). Heavy machinery
(Gg ¼ gigagram ¼ 109 g, Tg ¼ teragram ¼ 1012g) (McCartyet al., operations under certain soil types (e.g. heavy-textured soil) and
2009b). Particulate matter and trace gases emitted by burning wet conditions negatively impact soil structure, leading to
impact air quality and public health on local and regional scales compaction and reduced infiltration rates. Thus, under intense
(Adler,2010).IntheUS,annualPM2.5emissionestimatesfromApril rainfallorirrigation,surfacerunoffcouldoccur,leadingtolossand/
toDecemberwere3.49(cid:1)105(2002),3.30(cid:1)105(2003),1.80(cid:1)105 or landscape redistribution of sediments, OC, and nutrients, and
(2004), and 2.24 (cid:1) 105 (2005) tons, with the lead contributing othercontaminants(Neelyetal.,1989;RitterandShirmohammadi,
states being Oregon (24.7%), Montana (23.7%), California (17.7%), 2000;Allan,2004).TheNRCSNationalResourceInventoryreported
andLouisiana(10.2%)for2002,2003,2004,and2005,respectively 960and765milliontonsofsoilerosionlossfromcroplandbywater
(Zhang et al., 2008). Biomass burning also contributes to land (sheetandrill)andwind,respectively,in2007(NRCS,2007).These
degradation by destroying OM and by the formation of hydro- numbers stress the need for conservation tillage operations and
phobic compounds which could impede water infiltration. Soils practicesresultinginretentionofsurfaceresidues(>50%forno-till
underburninghaveanincreasedsusceptibilitytorunoff(DeBano and30e50%forminimumtill)asopposedtoconventionaltillage
et al., 1998; Udeigwe et al., 2010). The short- and long-term practices (<30% surface residues) that involve multiple tillage
impact of burning on desirable soil properties (e.g. OM content, passesandmoresurfacesoildisturbancewhichareimplicatedin
fertility status, microbial activity, water holding capacity, etc.) soildegradation,aswellasairandwaterqualityimpairments(Tan
(Pietika€inenandFritze,1993;DeBanoetal.,1998;Udeigweetal., et al., 2002; Liebig et al., 2004). From an agronomic perspective,
2010)and the associated impactonairand waterquality remain nutrient and OC losses are often associated with sediment loss,
undeniablyahugeenvironmentalthreat. particularlyinfieldsthatareconventionallytilled.VanOostetal.
(2007), in evaluating the contribution of agricultural soil erosion
2.4. Irrigation to global carbon cycle showed that a significant amount
(0.47e0.61PgC/year)ofsoilorganiccarbon(SOC),resultingfrom
Agricultureaccountsforover80%ofUSconsumptivewateruse agriculturalerosion,moveslaterallyovertheearth'ssurface,with
and evenhigher (90%) in the Mountainregions(Idaho, Montana, about0.32PgC/yearresultingfromcroplandalone.
Wyoming, Arizona, New Mexico, Colorado, Nevada, and Utah)
(GollehonandQuinby,2006). 3. Majorcontaminantsfromagriculturalsourcesandtheir
About54.9millionacresofirrigatedfarmlandwasreportedin environmentalimplications
the 2008 Farm and Ranch Irrigation Survey by the USDA, a 4.6%
increasefrom2003(USDA,2008).In2000,85%oftotalagricultural 3.1. Soil-andwater-bornecontaminants
withdrawalsofirrigationwateroccurredina19-stateareawithin
the Mountain, Plains, and Pacific regions (Gollehon and Quinby, Nutrients,traceelements,pesticides,pathogens,andradioactive
2006).StateswiththelargestareaofirrigatedlandareNebraska, materials are among the principal contaminants of agricultural
California, Texas, Arkansas, and Idaho (USDA, 2008). In the year origin. The close association/interaction of soil and water in the
2000,59%oftotalirrigationwithdrawalswerefromsurfacewater environmentfacilitatesthemobilityandtransferofcontaminants
sources and the rest from groundwater supplies (Gollehon and between the two systems; as a result, most soil-borne contami-
Quinby, 2006). However, the trend within the past decade in- nantsarealsoassociatedwithwaterqualityimpairment.
dicatesanincreasingdependenceongroundwater,whichsupplies Nutrients,particularlyNandP,fromagriculturalsources,have
mostoftheirrigationwaterintheeastern37statesnotedforthe oftenbeendocumentedaskeysoil-andwater-bornecontaminants
greatestirrigationgrowth(GollehonandQuinby,2006). (DavidandGentry,2000;Kleinmanetal.,2002;Hartetal.,2004).
Excessive irrigation often facilitates surface water runoff from Frequentlydocumentedanthropogenicsourcesofnutrientinputto
agricultural soils include inorganic fertilizers, animal manures, highly mobile and persistence compounds and includes atrazine
biosolids, and crop residues (Pritchard et al., 2010; Holm et al., (and deethylatrazine), metolachlor, prometon, and simazine
2010;Staceyetal.,2010).Prolongedlandapplicationofthesema- (Gilliom et al., 2006). In fish and sediments, historically reported
terials beyond plant needs could lead to accumulation of excess organochlorine pesticides, their degradates and by-products
nutrientsinsoilsandthesubsequentreleasetowaterbodies.Pri- include dichlorodiphenyltrichloroethane (DDT) group com-
(cid:3)
mary forms of N in soil and watersystems include nitrite(NO2), pounds, chlordane compounds, dieldrin, and heptachlor epoxide
(cid:3) þ
nitrate (NO3), ammonia (NH4), nitrous oxide (N2O), nitric oxide (degradate of heptachlor) (Gilliom et al., 2006). Pesticides in
(NO),elementalN(N2)andorganicN(Sawyeretal.,2003;Havlin groundwater,andmostresiduespresentinsurfacewaterentervia
etal.,2013)andtheseformsarechieflycontrolledbythechemis- thesoil(Arias-Este(cid:2)vezetal.,2008).Pesticideoccurrenceandcon-
try(pH,redoxpotential,etc.)andmicrobialactivityofthemedium centration in soil, surface and groundwater reflect their
(Havlinetal.,2013;Sawyeretal.,2003).Phosphorusinsoilewater geographical distributions (e.g. the US Corn Belt), and are influ-
(cid:3)
system could broadly be grouped into orthophosphate (H2PO4, enced by a combination of factors such as climate, agricultural
HPO4(cid:3)2), organic P, and complexed P (Fe/AlPO4 and CaHPO4). management practices (tillage, irrigation, drainage, etc.), soil
Mobility and bioavailability of P in the environment is generally characteristics, climate, and hydrogeology (Gilliom et al., 2006).
controlledbysoilminerals,pH,otherions,OM,Psaturation,time, Theenvironmentalfateofpesticidesiscontrolledbyacombination
andtemperature(Sparks,2003;Sposito,2008).PhosphorusandN of biological, chemical and physical factors which include degra-
are often transported during surface runoff (dissolved and dation (chemical and microbial), sorption, desorption, volatiliza-
sediment-boundPandN),leaching(dissolvedPandN)andpref- tion, leaching, runoff, and plant uptake (Wheeler, 2002; Arias-
erential flow (dissolved N) from contaminated soils to surface Este(cid:2)vez,2008).
waterbodies (Follett and Hatfield, 2001; Radcliffe and Cabrera, Pathogens commonly associated with the agricultural use of
2006).Soilandwatercontaminationbypotassiumisconsidereda sewage sludge/biosolids and animal manure include: Salmonella
lesserthreattoenvironmentalqualityandhealthandisnotoften spp, Shigella spp, Listeria monocytogenes, Helicobacter pylori,
cited(Baertetal.,1996). Campylobacter spp, Coxsackievirus, hepatitia A virus, rotavirus,
HeavymetalssuchasCu,Cd,Ni,Zn,Cr,cobalt(Co),manganese Cryptosporidium,Giardialamblia,Toxoplasmagondii,Escherichiacoli,
(Mn),andHg,aswellasotherelements suchasAs,S,aluminum Leptospira spp, Cyclospora, Microsporidia, and Brucella spp (Gerba
(Al),andiron(Fe)haveoftenbeenfoundintoxicamountsinmany and Smith, 2005; Gerba et al., 2011). These pathogens are intro-
agricultural soils (Adriano, 2001). Atmospheric deposition and ducedintosoilewatersystems,andsubsequentlytothefoodchain
anthropogenic sources such as sewage sludge/biosolids, animal when untreated and/or improperly treated wastes are surface
manures, composts, agricultural chemicals (fertilizers and lime), applied to agricultural soils, and also by direct discharge from
irrigation water, and industrial wastes, are the frequently cited storage units (Gerba and Smith, 2005; Pepper et al., 2006). A
sources of metal input to agricultural soils in England and Wales summaryof pathogen densities inprimaryand secondarysludge
(Nicholsonetal.,2003).Thefate of theseelementsinsoilewater arepresentedinTable2.Theenvironmentalfateofmostpathogens
systemsis influenced byfactorssuchas pH, redox potential, clay is influenced by a number of variables. Soil moisture favors mi-
minerals,andOM(Adriano,2001;Sposito,2008).Overtime,metals crobialsurvival,andclayenhancestheiradsorptiontosoilsurfaces,
such as Cu, Fe, Mn, and Zn could accumulate in soils, sorbed by reducing die off and facilitating transport (Santamaría and
plants(intothefoodchain)(Aroraetal.,2008),ormovethrough Toranzos, 2003). Pathogen survival tends to be lower in sandy
surface runoff and leaching to surface and groundwater (Rattan soilsduetopoorwaterholdingcapacity(SantamaríaandToranzos,
etal.,2005). 2003).OtherfactorsthataffectpathogensurvivalincludepH,OM
Thepresenceofradioactiveelementsinsoilandwatersystems content,andtemperatureofthemedium(Demolingetal.,2007).
hasalsobeentiedtoanumberofagriculturalmaterials.Phosphate Microbial transport from soil to water systems is facilitated by
fertilizersandphosphogypsum(aby-productfromphosphatefer- factors such as water saturation, soil texture, and rainfall
tilizerplantscommonlyusedasasourceofCaamendmenttosoils) (SantamaríaandToranzos,2003;Maieretal.,2009).
have been documented as potential sources of uranium (U),
thorium (Th), radon (Rn), polonium (Po), and radium (Ra)
Table2
(Papastefanouetal., 2006;Santosetal., 2006; Abril etal., 2009). Pathogendensitiesinprimaryandsecondarysludges.a
Phosphogypsumappliedattherateof20Mgha(cid:3)1wasassociated
withtheadditionsof3.0,15,and12MBqha(cid:3)1of238U,226Ra,and Pathogen Densityinprimary Densityinsecondary
210Po, respectively, to the treated soils (MBq ¼ megabecquerel, Sludges(/gofdrywt) Sludges(/gofdrywt)
106 Bq). The exhalation of 222Rn froma stackof phosphogypsum Virus
andtreatedsoilswasfoundtobecorrelatedwiththeconcentration Variousentericviruses 102(cid:3)104 3(cid:1)102
of226Ra(Abriletal.,2009).Theapplicationofflyashtoagricultural Bacteriophages 105 e
Bacteria
soilstoaddplantmicro-andmacro-nutrientshasalsobeenasso- Totalcoliforms 108(cid:3)109 7(cid:1)108
ciatedwiththeintroductionofradioactiveelementssuchas238U, Faecalcoliforms 107e108 8(cid:1)106
232Th, 226Ra, 228Ra, 222Rn and 220Rn to the soil (Mandal and Enterococci 106e107 2(cid:1)102
Sengupta, 2003; Papastefanou, 2008), although the levels were Salmonellaspp 102e103 9(cid:1)102
Clostridiumspp 106 e
reported to be within the permissible limits (Pandey and Singh,
Mycobacterium 106 e
2010).
Protozoa
Pesticides(includingpesticidedegradates)frequentlydetected Giardiaspp 102(cid:3)103 102e103
(between1992and2001)inUSsurfacewaters(streams)areamong Helminths
thosewhichareheavilyusedandincludetheherbicides:atrazine Ascarisspp 102e103 103
Trichurisvulpis 102 <102
(its degradate-deethylatrazine), metolachlor, cyanazine, alachlor, Toxocaraspp 10e102 3(cid:1)102
acetochlor, simazine, prometon, tebuthiuron, 2,4-
Primarysludge:settledsolidsobtainedaftergravitysedimentationofwastewater.
dichlorophenoxyacetic acid (2,4-D), and diuron, and the in-
Secondary sludge: product obtained after further biodegradation by
secticides; diazinon, chlorpyrifos, and carbaryl (Gilliom et al.,
microorganisms.
2006). The pesticides detected in groundwaters are mostly the a AdaptedfromLepeupleetal.(2004),afterStraubetal.(1993).
3.2. Air-bornecontaminants NO,NO2,N2O,carbonylsulfide(COS),CH4,methylchloride(CH3Cl)
are common products of biomass burning discharged to the at-
Airpollutantssuchasparticulatematters(PM2.5,PM10),oxides mosphere.Duringburningofplantresidue,Cisreleasedmostlyin
ofN,CandS,aswellasNH3,CH4,H2S,volatileorganiccompounds, theformofCO2,CO,partiallyoxidizedorganiccarboncompounds,
andpathogenshavebeencommonlytiedtobiomassburningand and particulate carbon, while nitrogen (mostly occurring as an
surfaceapplicationofbiosolidsandanimalmanures(McCartyetal., amino group), is released typically as N2, NO, N2O, NH3, and
2009a; Chadwick et al., 2011) as well as emissions from feedlots hydrogen cyanide (HCN), and sulfur is released as SO2, COS, SO4
(BeaucheminandMcGinn,2005;Fleschetal.,2007).Conventional (non-volatilesulfate)(Levineetal.,2010).Carbondioxide,N2O,CH4
tillage, a practice that involves maximum surface disturbance arenotedasgreenhousegases(Levineetal.,2010),whileNOx,CO,
achieved by disking, plowing, and other techniques utilized to andCH3Clareoftencitedasozoneprecursorgases(Hodzicetal.,
loosenthesoilandburycropresidues,alsoimpactairqualitybythe 2007). According tothe 2010 U.S. Climate Action Report, agricul-
releaseoffinedustanddebrisintotheatmosphere(Holland,2004; ture contributes 12% of total greenhouse gas emission (US
Baker et al., 2005; Kasumba et al., 2011). The composition of PM DepartmentofStates,2010).Apart frombiomassburning,micro-
dependsonseveralfactorsbutstudieshaveshownthatthemajor bialdecompositionoforganicresiduesisalsoacommonpathway
components are transition metals, ions (such as sulfate, nitrate), of CO2, NH3, CH4, and H2S emission to the environment (Møller
organic compounds, reactive gases, biologic materials, and soil et al., 2004; Chadwick et al., 2011). Methane release from live-
particles(Valavanidisetal.,2008).Particulatemattercomposition stock production is one of the most important sources of CH4
could vary depending on the type of agricultural practices. For contribution to the atmosphere. However, natural wetlands and
instance, PM from livestock units could consist of 90% organic ricepaddiesunderanaerobicconditionsarealsoimportantpath-
materials, composed of microorganisms (bacteria, fungi, viruses, waysofatmosphericgasdischarge(Levineetal.,2010).
etc), feed, skin, and fecal particles (Seedorf and Hartung, 2000; Air-borne pathogen release tothe atmosphere has been asso-
Cambra-Lo(cid:2)pez et al., 2010). On the other hand, particles emitted ciatedwiththeprocessing(ShammasandWang,2009)andsurface
through burning of crop residues often contain sulfur, organic application of biosolids and animal manures. The fungus, Asper-
components and black carbon (Adler et al., 2011), gaseous com- gillusfumigatusamongotherairbornepathogens,hasbeendetec-
pounds(e.g.COandvolatileorganiccompounds),andparticulate tedinsignificantamountsduringbiosolidcomposting(Shammas
compounds (Saarikoski et al., 2007). Particulate emission from and Wang, 2009). Thermophilic actinomycetes such as Saccha-
disking and harvesting could contain more of carbonaceous ma- ropolyspora faeniand Thermoactinomycesvulgaris, andthe fungus
terials and soil particles. The chemical componentsof particulate Aspergillus fumigates have also been reportedly released during
mattercouldalsovarygreatlydependingonthetypeofcropres- animalmanurecomposting(Epsteinetal.,2001;Receretal.,2001).
idue.Particulatematteremissionfromburningofwheatresidues Air-bornemesophilic,xerophilicandthermophilicmicroorganisms
wereshowntoconsistof31%K(byweight)and36%Cl,whilePM (bacteria and fungi) were detected in significant amounts
emittedfromthecombustionofriceresidueswascomposedof84% (4.4(cid:1)102e1.7(cid:1)106CFU/m3,CFU¼colonyformingunitspercubic
carbonaceous materials (Hays et al., 2005). Recent studies have meter)intheairfrompoultrylitterburningplants,withAspergillus
reportedthedetectionofpolycyclicaromatichydrocarbons,poly- niger, Eurotium herbariorum and Scopulariopsis brevicaulis species
chlorinateddibenzo-p-dioxins,andpolychlorinateddibenzofurans amongthedominantfungiobservedinair(Wultschetal.,2010).
associated with the burning of agricultural product residues
(EstrellanandIino,2010). 4. Contaminantimpactsonhumanhealth
BiomassisprimarilycomposedofC,oxygen(O),hydrogen(H),
N,P,S,andK.Consequently,gaseouscompoundssuchasCO,CO2, The development of maximum permissible concentrations
Table3
Contaminantscommonlylinkedtoagriculturalsourcesandtheirpermissiblelimitsinsoilanddrinkingwater.
Contaminant MPC(mgkg(cid:3)1)forsoil/MCL(mgL(cid:3)1)fordrinkingwater References
USEPA EC WHO
Nutrients
Phosphorus (cid:3)/(cid:3) (cid:3)/(cid:3) (cid:3)/(cid:3)
Nitrogen e/44.3a e/50.0a e/50.0a Selinus,2013
Heavy/traceelements
Nickel 210/e 30e75/0.02 e/0.02 Kabata-Pendias,2010;KumarandPuri,2012;Selinus,2013
Cadmium 20.0/0.005 1e3/0.005 e/0.003 Kabata-Pendias,2010;KumarandPuri,2012;Selinus,2013
Copper 750/1.3 50e140/2.0 e/1.0 Kabata-Pendias,2010;KumarandPuri,2012;Selinus,2013
Lead 150/0.015 50e300/0.01 e/0.01 Kabata-Pendias,2010;KumarandPuri,2012;Selinus,2013
Arsenic e/0.01 e/0.01 e/0.01 Kabata-Pendias,2010;KumarandPuri,2012;Selinus,2013
Pesticides
Total (cid:3)/(cid:3) e/0.005 (cid:3)/(cid:3) Hamiltonetal.,2003
Air-boneparticulates
PM25 (12.0)b (cid:3)/(cid:3) (cid:3)/(cid:3) USEPA,2013
PM10 (150)b (cid:3)/(cid:3) (cid:3)/(cid:3) USEPA,2013
MPC;MaximumPermissibleConcentration.
MPL;MaximumContaminantLimit.
USEPA;UnitedStatesEnvirormentalProtectionAgency.
EC;EuropeanCommission.
WHO;WorldHealthOrganization.
a Nitrogenmeasuredasnitrate(NO3).
b unitexpressedinmgofpartiuclatematterinm3ofair.
Table4
Contaminantscommonlylinkedtoagriculture-relatedactivities/sourcesandtheirassociatedimpactsonhumanhealth.
Contaminant Agriculture-related Humanexposure Associatedhealth Reference
source/activities implications
Nutrients Landappliedandstored Ingestionof
sewagesludge/ contaminatedfoodand
biosolids,animal water
manuresandinorganic
fertilizers;andcrop
residues
Phosphorus Cardiovascularrisks Kalantar-Zadehetal.,
2010
Couldworsenchronic
kidneydiseases
Nitrogen Methemoglobinemia WolfeandPatx,2002;
Fawelland
Nieuwenhuijsen,2003
Carcinogeniceffect Weyeretal.,2001;
(bladder,prostate, Fawelland
ovary,stomach,and Nieuwenhuijsen,2003
liver)
Heavy/tracemetals Sewagssludgs/ Ingestionof
biosolids;animal contaminatedfoodand
manures; water
agrochemicals(e.g.
fertukuzersandlime);
irrigationwater;and
industrialwastes.
Nickel Allergicskinreaction Dasetal.,2008
Carcinogenic, Guptaetal.,2006;Das
neurologic, etal.,2008
reproductive,
developmental,and
immunologiceffects
Cadmium Nephrotoxic(kidney Kobayashietal.,2008;
tubulardamage;and J€arupandÅkesson,
renalfailure) 2009
Copper Oxidativestress;liver Gaetkeandchow,
disease;and 2003;Uriu-Adamsand
neurologicaldefects. Keen,2005
LinkedtoAlzheimer's Mirandaetal.,2000;
diseaseandWilson's Opazoetal.,2002;
disease Mulleretal.,2004
Lead Imitatescalciumand LidskyandSchneider
interactswithprotein etal.,2003;Meyer
etal.,2008
Neurologicaland Meyeretal.,2008;
intellectual Payne,2008
impairments
Arsenic Accumulatesintissues Kapajetal.,2006
(skin,hair,andnails)
Cardiovascular Leeetal.,2002
diseases;renaldisease;
andchroniclung
disease,
Cancer(ofthelungs, Moralesetal.,2000
skin,liver,bladderand
kidney)
Neurologicaland Miltonetal.,2005
reproductiveeffects
Spontaneousabortion, Hopenhayn-Richetal.,
stillbirthandinfant 2000
mortality
Pathogens Sewagesludge/ Consumptionof
biosolids;andanimal contaminatedfoodand
manuresq water;andinhalation
ofcontaminatedair
Bacteria
Campylobacter; Gastroenteritis SidhuandToze,2009
Salmonella;Shigella
Helicobacterpyroli Gastriculcerandgastric Engstrand,2001
cancer
Legionella Respiratoryillness SidhuandToze,2009
Protozoa
Giardiaand Gastroenteritis Adam,2001
Cryptosporidium
(continuedonnextpage)
Table4(continued)
Contaminant Agriculture-related Humanexposure Associatedhealth Reference
source/activities implications
Enterocytozoon Diarrhea Mathisetal.,2005
bieneusiand
Encephalitozoon
intestinalis
Helminth
Ascarislumbricoides; Helminthinfections VonSperlingetal.,
Toxocara; 2003;Schwartzbroad
Capillaria;Trichuris andBanas,2003
Pesticides Appliedandstored Ingestionof
pesticides contaminatedfood
(crop,livestock,
fish),andwater;and
inhalationof
particulatesand
volatiles
e.g.,organophosphate, Cancers(leukemiasand Lo(cid:2)pezetal.,2007
chlorinatedpesticides, lymphoma)
2,4-D,atrazine,butylate, Parkinson'sdisease Ascherioetal.,2006
diazinon,phorate, Increasedriskof Cranmeretal.,2000
carbofuran,lindane, diabetes,
chlordane/heptachlor, hyperglycemis,and
chlordane,toxaphene, hyperinsulinemia
dieldrin,etc. Prostatecancerrisk Alavanjaetal.,2003
Rectalcancer,lung Purdueetal.,2007
cancer,melanoma
Air-borneparticulates Biomassburning Inhalationof
contaminatedair
PM2.2andPM10Airborne Respiratoryandheart MacneeandDonaldson,
pathogense.g.,Aspergillus problems 2003;Leeetal.,2007
fumigatus,etc. Asthma;allergic Arbexetal.,2007;Tecer
rhinitis;upperand etal.,2008
lowerrespiratory
disease
OxidesofC,N,andS;NH3;CH4 Alterationin PijnenburgandDe
respiratoryphysiology Jongste,2008;Iqbal
etal.,2010
(MPC)ormaximumcontaminantlimits(MCL)(Table3)forwater effect of reactive free radical and peroxides) and the bonding to
and soil is vital for environmental and human health protection, sulphydrylgroupsofproteins(Dasetal.,2008).Exposuretonickel
particularlyinintenseagriculturalregionswherethesepermissible could cause the formation of free radicals in various human and
levels may be threatened. A summary of contaminants from animal tissues leading to increased lipid peroxidation and alter-
agriculture-related activities and the potential human health im- ationofDNAbases(Dasetal.,2008).Nickeltoxicityinperipheral
plications associated with them is presented on Table 4. High P tissues in the lungs, kidney, and liver has also been documented
intake, through contaminated food or water, could worsen the (Guptaetal.,2006;Dasetal.,2008).
conditionofindividualswithchronickidneydisease,andhasalso Human ingestion of cadmium occurs primarily through food.
been tied to cardiovascular risks (Kalantar-Zadeh et al., 2010). Cadmiumisknownforitsnephrotoxicity,inducingkidneytubular
Inorganic P forms are more readily absorbed by the intestine damage,whichonhigherorprolongedexposurecouldadvanceto
comparedtoorganicP(Uribarri,2006;Kalantar-Zadehetal.,2010). impaired glomeruli, leading to reduced filtration rate and conse-
Human ingestion of nitrate-contaminated food and water could quently renal failure (Kobayashi et al., 2008; Ja€rup and Åkesson,
endanger health by the direct formation of methemoglobin 2009).Increasedcancerrisksandmortalityhavealsobeenassoci-
(resultingfromnitrateoxidationoftheFeinhemoglobinfromFe2þ atedwithexposuretocadmium(Ja€rupandÅkesson,2009).Copper
toFe3þ)(WolfeandPatz,2002;FawellandNieuwenhuijsen,2003). toxicity in humans could result in oxidative stress, a disorder
Methemoglobinemia (or blue baby syndrome), often caused by involved in many human diseases, and eventually tissue damage
elevatedlevelofmethemoglobinintheblood,isparticularlycritical (GaetkeandChow,2003;Uriu-AdamsandKeen,2005).ChronicCu
ininfantsunder6monthsandoftenmanifestedthroughshortness toxicityhasalsobeenlinkedtoneurologicaldefectsandliverdis-
ofbreath,cyanosis,lossofconsciousness,nausea,vomiting,fatigue, ease(Uriu-AdamsandKeen,2005).Coppertoxicityhasalsobeen
dizziness,etc.(Knobelochetal.,2000;Boxalletal.,2009).Nitrate linked to a number of human diseases such as Wilson's disease
ingestion is also linked to the formation of carcinogenic nitroso (Müller et al., 2004) and to Alzheimer's disease (Miranda et al.,
compoundswhichareassociatedwithbladder,prostrate,ovarian, 2000;Opazoetal.,2002).
stomach, and liver cancers (Weyer et al., 2001; Fawell and Lead entry into the human body system could occur through
Nieuwenhuijsen,2003). ingestion and/or inhalation. The toxicity of lead is linked to its
Nickel exposure is known for its neurologic, reproductive, potential toinhibitor imitate the action of calcium as well as its
developmental, immunologic, and carcinogenic effects as well as interactionwithproteins(LidskyandSchneider,2003;Meyeretal.,
allergicskinreactiononhumans(Dasetal.,2008).Nickeltoxicityin 2008). Absorbed lead easily binds with the red blood cells and
humanoccursprimarilythroughthereductionofglutathione(an movestosofttissues,affectingalmosteveryorganandsystemin
antioxidant that defends cellular components from the harmful thebody.Over90%ofleadintheadultbodysystemisfoundinthe
bonesandteeth,whileabout70%ofleadinchildrenisdepositedin inducing and/or exacerbating respiratory and heart problems
theirbones(Meyeretal.,2008).Exposuretoleadisalsoassociated (MacNee and Donaldson, 2003; Lee et al., 2007). Awasthi et al.
with neurological and intellectual impairments and can lead to (2010) has also shown that small particles (PM2.5 and PM10),
death(Meyeretal.,2008;Payne,2008).Theadversehealtheffects which are the main components of the smoke produced bycrop
of lead are more pronounced in children (Lidsky and Schneider, residue burning impact pulmonary function tests in children.
2003). Likewise,theincreaseintheconcentrationofsuspendedparticles
Humanexposuretoarsenichasbeenassociatedwithanumber producedduringtheburningofsugarcaneresidueswascorrelated
ofhealthconcerns.Arsenichasbeenshowntoaccumulateintis- with the number of hospital admissions of asthmatic patients in
sues suchasskin, hair, andnails and hasbeen linked tovascular Brazil(Arbexetal.,2007).Increasesinatmosphericconcentrations
disease,renaldisease,chroniclungdisease,cancer(oflungs,skin, ofPMwerealsoreflectedinsignificantincreasesinasthma,allergic
liver, bladder and kidney), as well as to neurological and repro- rhinitis, upperand lower respiratory disease admissions; while a
ductiveeffects(Moralesetal.,2000;Leeetal.,2002;Miltonetal., 10mg/m3increaseinPM10e2.5ledto18%riseinasthmaadmission
2005). Arsenic exposure has also been linked to the impairment (Tecer et al., 2008). Exposure to oxides of C, N, and S, emitted
of intellectual function and retarded growth in children throughanumberofagriculture-relatedactivitiessuchasbiomass
(Wasserman et al., 2004). Consumption of arsenic contaminated burningandapplicationofanimalmanureandbiosolids,hasalso
water has also been shown to be associated with spontaneous been linked to alteration in respiratory physiology, illnesses and
abortion, stillbirth and infant mortality (Hopenhayn-Rich et al., death(PijnenburgandDeJongste,2008;Iqbaletal.,2010).
2000).
Pathogens from agricultural sources invade the human body 5. Conclusionsandperspectives
systemthroughtheconsumptionofcontaminatedfoodandwater,
and inhalation of contaminated air. Human noroviruses, rotavi- Thisworkexploredthemainagriculturalactivitiesofenviron-
ruses, and astroviruses are the major causes of gastroenteritis in mental concerns; air, water, and soil-borne contaminants from
adults and children worldwide (Kirkwood et al., 2004). Bacterial agriculturalorigins;andtheassociatedhumanailmentslinkedto
pathogenssuchasCampylobacter,SalmonellaandShigella,arealso someofthesepollutants.Theuseofbiosolids,animalmanure,and
linked to bacterial gastroenteritis (Sidhu and Toze, 2009). Heli- agricultural chemicals; and practices such as burning of post-
cobacter pyroli is associated with gastric ulcer and gastric cancer harvestresidues,irrigation,andtillage operationsarevitaltothe
(Engstrand,2001).Legionella(anon-entericpathogen)islinkedto economicproductionoffoodandfiber.However,theyalsoposea
lifethreateningrespiratoryillnessintheelderly(SidhuandToze, numberofenvironmentalandhealthchallenges,thus,emphasizing
2009). Other bacterial pathogens such as Yersinia enterocolitica, the need for the adoption of research-based best management
Aeromonasspp.andBurkholderiacepaciamaycausegastroenteritis practices in our pursuit for sustainable agriculture. The weight
in childrenandcertain adults(Pengetal., 2002; SidhuandToze, placedonagriculturetoprovidefoodforthegrowingpopulationas
2009). Protozoan pathogens such as Giardia and Cryptosporidium wellasfeedstockforalternativeenergysources,hasunfortunately
are also linked to gastroenteritis (Ho€rman et al., 2004). Human led to the intensification of some of these aforementioned prac-
pathogenic microsporidia (Enterocytozoon bieneusi and Encephali- tices.However,thereishardlyanyargumentthattheneedforfood
tozoon intestinalis) are noted for causing diarrhea, particularly in inmostpartsoftheworldcurrentlyoutweighstherisksassociated
individuals with low immunity (Mathis et al., 2005). Helminth withthesepractices.
infection caused by Ascaris lumbricoides, Toxocara, Capillaria, Tri- Althoughnotthefocusofthispaper,thechangingclimatecould
churis, etc. are also prevalent in biosolids, sewage sludge, and exacerbate the environmental and human health implications of
wastewater impacted areas (Von Sperling et al., 2003; agricultural intensification. For instance, increasing temperature
SchwartzbrodandBanas,2003. couldleadtomoreevaporativelossesofwater,thuscreatingmore
Pesticidesfromagriculturalsourceshavebeenassociatedwitha droughtyconditionsthatcouldexposesurfacesoilstotheerodible
number of health hazards in humans. Frequent exposure to low forces of wind and water. Excessive rainfall could increase the
levels of organophosphate has been linked to risks of cancers chances of surface runoff of agricultural chemicals and applied
(leukemias and lymphoma) and other biochemical effects (Lo(cid:2)pez nutrient to receiving waterbodies. The depletion of groundwater
et al., 2007). Alavanja et al. (2003) reported an association be- quantityandqualityasaresultoflowrechargepotential,whichis
tween the use of chlorinated pesticides and methyl bromide and partlyduetolowprecipitationandincreasingdependence,isalso
prostatecancerrisk.Parkinson'sdiseasehasbeenassociatedwith resulting in increasing contaminant levels in most groundwater-
exposuretopesticides(Ascherioetal.,2006).FindingsbySaldana irrigated agricultural soils. In the same line with our discussion,
etal.(2007),suggestthatexposuretotheherbicides2,4-D,atra- previously identified consequences of the changing climate on
zine, and butylate, and the insecticides diazinon, phorate, orcar- agricultureincludeincreased(a)useofpesticidesandbiocidesas
bofuranduringthefirsttrimesterofpregnancycouldincreasethe farmingpracticesintensify,(b)potentialofcontaminanttransport
risk of gestational diabetes mellitus. Increased risk of type 2 dia- towatersupplies,(c) mobilizationand bioavailabilityofsoilcon-
betes,hyperglycemia,andhyperinsulinemiahasalsobeenlinkedto taminants,andthus,(d)humanexposuretoagriculturalchemical
pesticideexposure(Cranmeretal.,2000).Studieshavealsoshown contaminantsandpathogens.
thatexposuretoorganophosphateandorganochlorineinsecticides Evidencegatheredinthecourseofthisreviewsuggeststheneed
is linked to alteration in the activities of enzymes involved in forthecontinualimplementationofresearch-backedmeasuresto
glucose metabolism and increase in insulin and blood glucose meet the pace of intensification of agricultural activities. Several
levelsinanimals(Abdollahietal.,2004).Possibleassociationsbe- keymanagementpracticescanbereemphasizedandemployedto
tween(a)non-Hodgkinlymphomaandlindane,(b)leukemiaand mitigate the effects of current and future practices of organic
chlordane/heptachlor, (c) rectal cancer and chlordane, (d) mela- amendmentandagriculturalchemicaluses,residueburning,con-
nomaandtoxaphene,(e)lungcanceranddieldrinhavealsobeen ventionaltillage,etc.,thataccentuatetheirnegativeimpactonthe
reported(Purdueetal.,2007),althoughnoclearrelationshipsbe- environment and human health: (1) Application rates of manure
tweencancerriskandorganochlorineswereobserved. and biosolids must follow basic guidelines, which account for
Particulatematters(particularlyPM10)releasedduringagricul- inherent soil nutrient content, crop nutrient requirement, and
turalresidueburningifinhaled,caneasilypenetrateintothelungs availability of the added nutrient. Effort should also be made to