Analysis of Pesticides in Food and Environmental Samples - Chapter 1 doc

Analysis of Pesticides in Food and Environmental Samples focuses on theanalytical methodologies developed for the determination of these compounds and on their levels in food and in the

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Analysis of pesticides in food and environmental samples / editor, Jose L Tadeo.

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ISBN 978-0-8493-7552-1 (alk paper)

1 Pesticide residues in food 2 Food Analysis 3 Pesticides I Tadeo, Jose L

Preface

Editor

Contrib utors

Chapt er 1 Pesticides : Classi fication and Properties

José L Tadeo, Consuel o Sánchez -Brunet e,

and Lorena González

Chapt er 2 Sample Hand ling of Pe sticides in Food and Env ironment al

Samples

Esther Turiel and Antoni o Mart ín-Esteban

Chapt er 3 Analysis of Pesticides by Chroma togra phic Tec hnique s

Coupled wi th Mass Spectromet ry

Simon Hird

Chapt er 4 Immunoas says and Biosens ors

Jeanet te M Van Emon, Jane C Chuang, Kili an Di ll,and Guoh ua Xio ng

Chapt er 5 Quality Assurance

Árpád Ambru s

Chapt er 6 Determinat ion of Pesticides in Food of Vegetal Origin

Frank J Schenck and Jon W Wong

Chapt er 7 Determinat ion of Pesticides in Food of Animal Origin

Antoni a Garrido Frenich , Jose Luis Mart inez,

and Adrian Covaci

Chapt er 8 Determinat ion of Pesticides in Soil

Con suelo Sánchez -Brunet e, Beatriz Albero,

and José L Tadeo

Chapter 9 Determination of Pesticides in Water

Jay Gan and Svetlana Bonda renko

Chapter 10 Sampling and Analysis of Pesticides in the Atmosphere

Maurice Millet

Chapter 11 Levels of Pesticides in Food and Food Safety Aspects

Kit Gra nby, Ann ette Peters en, Susan S Her rmann,

and Mett e Erecius Pou lsen

Chapter 12 Monitoring of Pesticides in the Environment

Ioannis Konstan tinou, Dimi tra Hela, Dimitra Lambrop oulou,and Tr iantafyllos Albani s

You should go on learning for as long as your ignorance lasts;

and, if the proverb is to be believed, for the whole of your life

Lucius Annaeus Seneca

Consumer concerns on food safety and society awareness of chemical contaminants

in the environment have increased in the past few years As a consequence, morerestrictions in the use of chemical products have been imposed at national andinternational levels

Pesticides are widely used for the control of weeds, diseases, and pests ofcultivated plants all over the world, mainly since after Second World War, withthe discovery of some organic compounds with good insecticide or herbicideactivity At present, around 2.5 million tons of pesticides are used annually and thenumber of registered active substances is higher than 500

However, as pesticides are toxic substances that may have undesirable effects,their use has to be regulated Risk assessment of pesticides requires information onthe toxicological and ecotoxicological properties of these compounds as well as ontheir levels in food and environmental compartments Therefore, reliable analyticalmethods are needed to carry out the monitoring of pesticide residues in thosematrices

Analysis of Pesticides in Food and Environmental Samples focuses on theanalytical methodologies developed for the determination of these compounds and

on their levels in food and in the environment It includes information on the differentpesticides used, sample preparation methods, quality assurance, chromatographictechniques, immunoassays, pesticide determination in food, soil, water, and air, andthe results of their monitoring in food and environmental compartments I think thatthis timely and up-to-date work can significantly improve the information in thisresearch area and contribute to a better understanding of the behavior of pesticidesthat will lead to an improvement of their use

My sincere thanks to everyone who has contributed and particularly to all thecontributors of the different chapters of Analysis of Pesticides in Food and Environ-mental Samples

This work is dedicated to Teresa, my wife

José L Tadeo

In 1977, Dr Tadeo was a research scientist at the Institute for AgriculturalResearch in Valencia where his work focused on the study of the chemical compo-sition of citrus fruits and the behavior of fungicides used during postharvest of fruits.

In 1988, he became a senior researcher at the Instituto Nacional de Investigación

y Tecnología Agraria y Alimentaria During his stay at the Plant Protection ment, the main research lines were the analysis of herbicide residues and the study oftheir persistence and mobility in soil

Depart-His current research at the Environment Department of the Instituto Nacional deInvestigación y Tecnología Agraria y Alimentaria is the analysis of pesticidesand other contaminants in food and environmental matrices and the evaluation ofexposure to biocides and existing chemicals He has published numerous scientificpapers, monographs, and book chapters on these topics He has been a member ofnational and international working groups for the evaluation of chemicals, and he iscurrently involved in the assessment of biocides at the international level

Instituto Nacional de Investigación y

Tecnología Agraria y Alimentaria

Almeria, Spain

Lorena GonzálezDepartment of EnvironmentInstituto Nacional de Investigación yTecnología Agraria y AlimentariaMadrid, Spain

Kit GranbyThe National Food InstituteTechnical University of DenmarkSøborg, Denmark

Dimitra HelaDepartment of Business Administration

of Agricultural Products and FoodUniversity of Ioannina

Agrinio, Greece

Susan S HerrmannThe National Food InstituteTechnical University of DenmarkSøborg, Denmark

Simon HirdCentral Science LaboratorySand Hutton, York, United Kingdom

Ioannis KonstantinouDepartment of Environmental andNatural Resources ManagementUniversity of Ioannina

Agrinio, Greece

Instituto Nacional de Investigación y

Tecnología Agraria y Alimentaria

Madrid, Spain

Jose Luis Martinez

Department of Analytical Chemistry

Centre de Géochimie de la Surface

Université Louis Pasteur

Strasbourg, France

Annette Petersen

The National Food Institute

Technical University of Denmark

Søborg, Denmark

Mette Erecius Poulsen

The National Food Institute

Technical University of Denmark

Søborg, Denmark

Consuelo Sánchez-Brunete

Department of Environment

Instituto Nacional de Investigación y

Tecnología Agraria y Alimentaria

Madrid, Spain

Frank J SchenckSoutheast Regional LaboratoryU.S Food and Drug Administration

Office of Regulatory AffairsAtlanta, Georgia

José L TadeoDepartment of EnvironmentInstituto Nacional de Investigación yTecnología Agraria y AlimentariaMadrid, Spain

Esther TurielDepartment of EnvironmentInstituto Nacional de Investigación yTecnología Agraria y AlimentariaMadrid, Spain

Jeanette M Van EmonNational Exposure Research LaboratoryU.S Environmental Protection AgencyLas Vegas, Nevada

Jon W WongCenter for Food Safety and AppliedNutrition

U.S Food and Drug AdministrationCollege Park, Maryland

Guohua XiongNational Exposure Research LaboratoryU.S Environmental Protection AgencyLas Vegas, Nevada

1 Pesticides: Classification and Properties

José L Tadeo, Consuelo Sánchez-Brunete,

and Lorena González

CONTENTS

1.1 Introduction 2

1.2 Herbicides 4

1.2.1 Amides 5

1.2.2 Benzoic Acids 5

1.2.3 Carbamates 6

1.2.4 Nitriles 7

1.2.5 Nitroanilines 8

1.2.6 Organophosphorus 10

1.2.7 Phenoxy Acids 10

1.2.8 Pyridines and Quaternary Ammonium Compounds 12

1.2.9 Pyridazines and Pyridazinones 13

1.2.10 Triazines 14

1.2.11 Ureas 15

1.2.11.1 Phenylureas 15

1.2.11.2 Sulfonylureas 16

1.3 Insecticides 16

1.3.1 Benzoylureas 16

1.3.2 Carbamates 16

1.3.3 Organochlorines 19

1.3.4 Organophosphorus 20

1.3.5 Pyrethroids 20

1.4 Fungicides 23

1.4.1 Azoles 23

1.4.2 Benzimidazoles 23

1.4.3 Dithiocarbamates 26

1.4.4 Morpholines 26

1.4.5 Miscellaneous 27

1.5 Mode of Action 28

1.5.1 Herbicides 28

1.5.1.1 Amino Acid Synthesis Inhibitors 28

1.5.1.2 Cell Division Inhibitors 30

1.5.1.3 Photosynthesis Inhibitors 30

1.5.2 Insecticides 30

1.5.2.1 Signal Interference in the Nervous System 30

1.5.2.2 Inhibitors of Cholinesterase 31

1.5.2.3 Inhibitors of Chitin Synthesis 31

1.5.3 Fungicides 31

1.5.3.1 Sulfhydryl Reagents 31

1.5.3.2 Cell Division Inhibitors 31

1.5.3.3 Inhibitors of Ergosterol Synthesis 32

1.6 Toxicity and Risk Assessment 32

References 34

1.1 INTRODUCTION

A pesticide is any substance or mixture of substances, natural or synthetic, formu-lated to control or repel any pest that competes with humans for food, destroys property, and spreads disease The term pest includes insects, weeds, mammals, and microbes, among others [1]

Pesticides are usually chemical substances, although they can be sometimes biological agents such as virus or bacteria The active portion of a pesticide, known as the active ingredient, is generally formulated by the manufacturer as emulsifiable concentrates or in solid particles (dust, granules, soluble powder, or wettable powder) Many commercial formulations have to be diluted with water before use and contain adjuvants to improve pesticide retention and absorption by leaves or shoots

There are different classes of pesticides according to their type of use The main pesticide groups are herbicides, used to kill weeds and other plants growing in places where they are unwanted; insecticides, employed to kill insects and other arthropods; and fungicides, used to kill fungi Other types of pesticides are acaricides, mollusci-cides, nematimollusci-cides, pheromones, plant growth regulators, repellents, and rodenticides Chemical substances have been used by human to control pests from the beginning of agriculture Initially, inorganic compounds such as sulfur, arsenic, mercury, and lead were used The discovery of dichlorodiphenyltrichloroethane (DDT) as an insecticide by Paul Müller in 1939 caused a great impact in the control

of pests and soon became widely used in the world At that time, pesticides had a good reputation mainly due to the control of diseases like malaria transmitted by mosquitoes and the bubonic plague transmitted by fleas, both killing millions of people over time Nevertheless, this opinion changed after knowing the toxic effects

of DDT on birds, particularly after the publication of the book Silent Spring by Rachel Carson in 1962 [2] At present, due to the possible toxic effects of pesticides

on human health and on the environment, there are strict regulations for their registration and use all over the world, especially in developed countries However, although some progress is achieved in the biological control and in the development

of resistance of plants to pests, pesticides are still indispensable for feeding and protecting the world population from diseases It has been estimated that around one-third of the crop production would be lost if pesticides were not applied

Pesticide use h as incre ased 50-fol d since 1950 and around 2.5 million tons ofindustri al pesti cides per year are used nowa days Figure 1.1 show s the time course o fpesticide sales during the last years.

Acco rding to the Euro pean Crop Protec tion Associa tion (ECPA) Annu al Rep ort

2001 –2002, the main agric ultural areas of pesticide usage are North Ameri ca,Europe, and Asia with 31.9%, 23.8%, and 22.6%, respectively, in 2001 (Figure 1.2).These percentages of pesticide sales are expressed in millions of euros and, althoughthe mentioned regions are the most important agricultural areas in the global pesticidemarket, their relative position may vary due to changes in the currency exchange rates,climatic condit ions, and national policies on agric ultural support and regulatio ns.The amoun t of pe sticides appli ed in a deter mined geograp hical area depen ds onthe climatic condition s an d on the outbreak of pests and d iseases of a particula r year.Neverthel ess, herbicides are the main group of pesticide s used worldwide, foll owed

by insecticides and fungicides (Figure 1.3)

20,000 22,000 24,000 26,000 28,000 30,000 32,000

Europe Asia Latin

The de velopment of a new chemic al as a pesti cide takes at presen t nearl y

15 years and around $20 million, and only one co mpound out of 10,000 compo undsinit ially tested might reach, on average, final comm ercia l production The regis tra-tion of a pesticide for its applicati on on a particula r crop requi res a complete set ofdata to prove its ef ficacy a nd safe use This normally incl udes d ata on physicochem -ical proper ties , analyt ical methods, e ffi cacy, toxi cology , ecotox icology , and fate andbeh avior in the envir onmen t Residue s left on crops after pesticide appli cation havebee n restrict ed in develo ped countr ies to g uaranty a safe food consum ption Themaxi mum resi due level s (MR Ls) in different foods have been estab lished according to

go od agric ultural pract ices, the observed toxi c effects of the pesticide , and the amoun t

of food consum ed MR Ls are no rmally fi xed in relation with the admi ssible da ilyinta ke (ADI) of pestic ides, which is the amoun t of pesticide that can be ingested daily

du ring the whole life without showing an appreci able advers e effect MR Ls arepropos ed by the Joint FAO=WHO Meeting on Pesti cide Residue s (JMPR) andrecom mende d for adoption by the Codex Comm ittee on Pesti cide Res idues [3,4]

In the following sections of this chapte r, the mai n class es of pesticide s cides , insec ticides, an d fungi cides) wi ll be described together wi th their mai n

(herbi-ph ysicochemi cal proper ties and principal uses These data have been gather edmai nly from The Pesti cide Manual [5] as well as from the primary manufactur esource s [6,7] and other available p ublications [8,9]

1.2 HERBICIDES

The implem entation of mecha nization in agricultu re has increased the ability of

hu man to contr ol weed s and cultivat e crops; herbicides have p layed a main part inthis development ; and a higher propor tion of farmers would be needed if herbicideswere not used

Herbicides can be classified as soil- or foliage-applied compounds, which arenormally absorbed by roots or leaf tissues, respectively These compounds can be

0 10

World USA Europe

Herbicides Insecticides Fungicides

total or selective herbi cides Total herbi cides can kill all vegetation , wher eas selec ive herbi cides can control weeds without affect ing the crop These chemical sub-stances may be applied at different crop stages, such as presowi ng and pre- orpostemerg ence, and these diff erent treatmen ts will be used dependi ng on the weedneeded to be con trolled in a particula r crop The selec tivity of a herbi cide maydepend on a d ifferential plant uptake , translocat ion, or met abolism , as wel l as ondifferences at the sit e of action A know ledge of p hysicochem ical proper ties, that is,vapor press ure (V p.), octano l=water pa rtition coef ficient (Kow , expres sed in thelogarithm ic form log P), and solubili ty in water allo ws the fate and behavi or ofsuch c hemicals in the envir onmen t to be predi cted.

t-In addition, herbi cides can be classi fied accordi ng to their chemical c omposit ion.The princ ipal ph ysicochemi cal p roperties , together with the field persisten ce andmajor uses of repres entative herbicides , grouped in their main chemi cal class es, aredescribed late r

This group is mainly formed by chlorinated derivatives of substituted benzoic acids

Cl

CO2H OCH3

Cl Dicamba

The benzoi c acid herbi cides are kno wn to have grow th regulatin g and auxin acti vityproper ties These compo unds are especi ally used to contr ol deep-r ooted perennialweed s and ap plied as salt s or esters (Table 1.2).

1.2.3 C ARBAMATES

Car bamates are ester s of the carbamic acid (R1–O –CO –NR 2R3) and toget her withthio carbam ates (R1–S–CO –NR 2R3) represen t a broad group of herbic ides, freque ntlyapp lied to soil in preemergenc e

Water Solubility mg=L

Half-Life

in Soil (Days) Acetochlor

2-Chloro-6-ethyl-

N-(2-methoxy-1-methylethyl) acet- o-toluidide

a

208C.

These compo unds are root o r shoot absorbed and are freque ntly used to contr olannual grass es and broad- leaved weed s in peas, beet, and other horticultural c rops.These herbi cides are normally decompo sed by soil mic roorganism s in 3 –5 weeks.Their mai n physicochem ical proper ties are summari zed in Table 1.3.

CN

I OH I

They are form ulated as salts or octano ate ester s and foliage app lied to control leaved weed s in cereals and horticultural crops The se compo unds are used inpostemerg ence and freque ntly applied in combinati on with other herbicides toextend the spect rum of weed speci es to be contr olled They have a low persi stence

Vapor Pressure

Water Solubility g=L (258C)

Half-Life

in Soil (Days) Chloramben

dichlorobenzoic acid

Chlorthal-dimethyl

Dimethyl tetrachloroterephthalate

Dicamba

methoxybenzoic acid

Sources: Data from Tomlin, C (Ed.) in The Pesticide Manual, British Crop Protection Council, 2000;

http: ==ec.europa.eu=food=plant=protection=evaluation=exist_subs_rep_en.htm ; http: ==www.epa gov =opprd001=factsheets= ; Hornsby, A.G., Wauchope, R.D., and Herner, A.E in Pesticide Properties in the Environment, Springer-Verlag, New York, 1996; De Liñan, C in Farmacología Vegetal, Ediciones Agrotecnicas S.L., 1997.

Ni troanilines are a group of herbicides with sim ilar physicochem ical proper ties, such

as low water solubility and high octanol–water partition coefficient These compoundsare soil-applied herbicides used to control annual grasses and many broad-leaved

Vapor Pressure mPa

Water Solubility

Half-Life

in Soil (Days) Chlorpropham

chlorocarbanilate

Desmedipham

Ethyl-3-phenylcarbamoyloxy phenylcarbamate

EPTC

S-Ethyl dipropylthiocarbamate

Molinate

S-Ethyl carbothioate

Phenmedipham

(3-methylcarbaniloyloxy) carbanilate

Propham

Isopropyl phenylcarbamate

Sublimes slowly

Triallate

S-2,3,3-Trichloroallyl diisopropyl(thiocarbamate)

Sources: Data from Tomlin, C (Ed.) in The Pesticide Manual, British Crop Protection Council, 2000;

http:==ec.europa.eu=food=plant=protection=evaluation=exist_subs_rep_en.htm ; http:==www.epa gov =opprd001=factsheets= ; Hornsby, A.G., Wauchope, R.D., and Herner, A.E in Pesticide Properties in the Environment, Springer-Verlag, New York, 1996; De Liñan, C in Farmacología Vegetal, Ediciones Agrotecnicas S.L., 1997.

a

208C.

weeds in a wi de varie ty of crops The 2,6-dinit roaniline s posses s a mark ed generalherbicide activity Sub stitution at the third and=or fourth position of the ring or on theamino group modi fies the degree of herbi cidal activity In general, they have acertain persisten ce in soil and are normally soil incor porated due to thei r signi fi cantvapor pressure (Table 1.5).

Vapor Pressure

Water Solubility mg=L (208 C)

Half-Life

in Soil (Days) Bromoxynil

Vapor Pressure mPa

Water Solubility mg=L (258 C)

Half-Life

in Soil (Days) Butralin

N-sec-Butyl-4-tert-butyl-2, 6-dinitroaniline

Pendimethalin

dinitro-3,4-xylidine

1.2.6 ORGANOPHOSPHORUS

HO2CCH2NHCH2P(OH)2

O

Glufosinate Glyphosate

CH3PCH2CH2CHCO2H O

OH NH2

Gl yphosate and glufo sinate are broad spect rum, nonsel ective, poste mergen ce co ntactherbi cides ac tive only for foliar applicati on The y are extens ively used in vario usapp lications for weed con trol in aquati c systems and vegeta tion contr ol in noncropareas Aminome thylphosph onic acid (AM PA) is the maj or degrada tion product ofglypho sate found in plant s, wat er, and soil The main proper ties of these compo undsare show n in Table 1.6

1.2.7 P HENOXY A CIDS

Ph enoxy acids are a comm on name given to a group of compo unds formed by aphenoxy radical linked to a low carbon number alkanoic acid, such as 2,4-dichlorophe-

no xyacetic acid (2,4-D, ace tic acid) or mecoprop (propi onic acid) Some herbicides

of this group are form ed by ster eoiso mers, which are comm ercialize d as singl eena nthiomer s or racemic mixtures

Vapor Pressure

Water Solubility

Half-Life

in Soil (Days) Glyphosate

N -(Phosphonomethyl) glycine

Glufosinate-ammonium

Ammonium 4-[hydroxy(methyl)

Vapor Pressure

Water Solubility mg=L (208 C)

Half-Life

in Soil (Days) 2,4-D

a

208C.