Household pesticide usage in the United States

Household pesticide exposures and infant gross motor development in the MADRES cohort

BACKGROUND

The development of motor skills in infancy is a vital neurodevelopmental milestone. Although previous studies have explored the neurotoxic effects of agricultural pesticides on infants' motor development, limited research has examined early postnatal household pesticide use on infants' motor development, particularly among urban communities.

OBJECTIVE

This study examined the association between early postnatal household pesticide use and infants' gross and fine motor development at 6 months of age.

METHODS

Questionnaires were administered via telephone to 296 mother-infant dyads in the Maternal and Developmental Risks from Environmental and Social Stressors (MADRES) pregnancy cohort. Early life household pesticide use was assessed via questionnaire administered when infants turned 3 months old and gross and fine motor development was assessed by the Ages and Stages Questionnaire (ASQ-3) at 6 months old. Infant gross motor scores were reverse coded so that higher scores indicated lower gross motor performance. Negative binomial regressions were performed to assess the relationship between household pesticide use and infant gross motor development.

RESULTS

Infants were predominantly Hispanic (78.7%) and full term (gestational age at birth: 39.0 ± 1.9 weeks), with 22.3% of maternal participants reporting household use of rodent and insect pesticides. Adjusting for recruitment site, maternal age, ethnicity, household income, education, infant corrected age, infant sex, and home type, infants with maternal-reported household use of rodent and insect pesticides had 1.30 times higher expected gross motor scores (95% confiidence interval 1.05, 1.61) than infants with no reported use of household pesticides, with higher scores indicating reduced gross motor performance.

CONCLUSIONS

Our results suggest household use of rodent and insect pesticides may harm infants' gross motor development in early childhood. Future research should evaluate the impact of specific household chemicals in infant biospecimens and their associations with infant motor development to confirm these findings.

Domestic use of pesticides during early periods of development and risk of testicular germ cell tumors in adulthood: a French nationwide case-control study

BACKGROUND

Testicular germ cell tumours (TGCT) are the most frequent cancers in young men in developed countries and their incidence rate has doubled worldwide over the past 40 years. Early life exposures to pesticides are suspected to increase TGCT risk. Our research aimed at estimating adult TGCT risk associated with parental domestic use of pesticides during early periods of child development.

METHODS

We conducted a case-control study of 304 TGCT cases, aged 18-45 years old, recruited in 20 French university hospitals, and 274 controls frequency-matched on hospital and birth year. Participants' mothers provided information on their domestic use of pesticides from 1 year before start of pregnancy to 1 year after their son's birth, for gardening activities, treatment of indoor plants, pets, wood and mold, and pest control. Odds ratios (OR) for TGCT (overall and by histological subtype) and 95% confidence intervals (CI) were estimated using conditional logistic regression.

RESULTS

Prevalence of reported domestic use of pesticides was 77.3% for insecticides, 15.9% for fungicides and 12.1% for herbicides. While no association was found for any use of insecticides (OR = 1.27, CI = 0.80-2.01) or herbicides (OR = 1.15, CI = 0.67-2.00), elevated risks of TGCT overall (OR = 1.73, CI = 1.04-2.87) and non-seminoma subtype (OR = 2.44, CI = 1.26-4.74) were observed for any use of fungicides. When specific purposes were examined, using fungicides and/or insecticides for woodwork (OR = 2.35, CI = 1.06-5.20) and using insecticides on cats and dogs (OR = 1.95, CI = 1.12-3.40) were associated with increased risk of non-seminoma subtype. We found no association for seminoma subtype.

CONCLUSIONS

Although recall bias may partially explain the elevated ORs, our study provides some evidence of a positive association between domestic use of pesticides during early periods of development, particularly fungicides and risk of adult TGCT and non-seminoma. Given the common domestic use of pesticides in France, further research on TGCT risk is warranted.

Household pesticide exposure: an online survey and shelf research in the Metropolitan Region of Rio de Janeiro, Brazil

This study aimed to estimate household pesticide exposure in adult individuals in the Metropolitan Region of Rio de Janeiro, Brazil, and to verify the accessibility of these products in local and online businesses. The data were collected by an online questionnaire (1,015 responses) and a shelf survey in physical and online stores. Among the responses analyzed, 87.5% used pesticides in the previous year, most of which against mosquitoes (64.7%). The most common application method was aerosol spray (38.1%), and the most frequent places of use were bedrooms (29.7%) and living rooms (22.1%). About 30% of respondents reported invasion of pests, and the most common pests were ants (79.1%) and cockroaches (40.4%). Service area (71.6%) and kitchen (17.5%) were the most common storage locations. Approximately 91% of those who lived with children aged under 18 used pesticides. The use of chemical group of pyrethroids prevailed (81.6%), and 90.8% of the reportedly used products are class II [55.7% (highly toxic)] or class III [35.1% (medium toxic)]. The most significant amount of purchased products was in the pest category, followed by mosquitoes. More variety of products were available in online stores than in physical stores. The high exposure of the population to pesticides at household is a public health issue and confirms the need for studies that better assess the risks and consequences of chronic and low-dose exposure to these substances. It is essential to inform the population about the uncertainties and potential risks of indiscriminate use so that they can choose whether to use pesticides in their households.

Predictors of Urinary Pyrethroid and Organophosphate Compound Concentrations among Healthy Pregnant Women in New York

Our study aimed to investigate dietary and non-dietary predictors of exposure to pyrethroids, organophosphates pesticides and 2,4-D herbicide in two cohorts of pregnant women in New York City: 153 women from the Thyroid Disruption and Infant Development (TDID) cohort and 121 from the Sibling/Hermanos Cohort(S/H). Baseline data on predictors were collected from the women at time of recruitment. We used three different modeling strategies to address missing data due to biomarker values below the limit of detection (<LOD): (1) logistic regression models with biomarkers categorized as (<median, ≥median); (2) linear regression models, imputing the <LOD values with (LOD/√2); (3) regression models, considering <LOD values as left-censored. Generally, all three models identified similar predictors of exposure. We found that ethnicity, higher income and education predicted higher concentrations of most of the biomarkers in both cohorts. Mothers who consumed processed meat in the TDID cohort, and broiled, barbequed food or burgers in the S/H cohort, tended to have lower concentrations of organophosphates and 2,4-D. The choice of modeling led to a few different predictors identified, and the selection of modeling strategy should be based on the study question.

Household organophosphorus pesticide use and Parkinson's disease

BACKGROUND

Household pesticide use is widespread in the USA. Since the 1970s, organophosphorus chemicals (OPs) have been common active ingredients in these products. Parkinson's disease (PD) has been linked to pesticide exposures but little is known about the contributions of chronic exposures to household pesticides. Here we investigate whether long-term use of household pesticides, especially those containing OPs, increases the odds of PD.

METHODS

In a population-based case-control study, we assessed frequency of household pesticide use for 357 cases and 807 controls, relying on the California Department of Pesticide Regulation product label database to identify ingredients in reported household pesticide products and the Pesticide Action Network pesticide database of chemical ingredients. Using logistic regression we estimated the effects of household pesticide use.

RESULTS

Frequent use of any household pesticide increased the odds of PD by 47% [odds ratio (OR)=1.47, (95% confidence interval (CI): 1.13, 1.92)]; frequent use of products containing OPs increased the odds of PD more strongly by 71% [OR=1.71, (95% CI: 1.21, 2.41)] and frequent organothiophosphate use almost doubled the odds of PD. Sensitivity analyses showed that estimated effects were independent of other pesticide exposures (ambient and occupational) and the largest odds ratios were estimated for frequent OP users who were carriers of the 192QQ paraoxonase genetic variant related to slower detoxification of OPs.

CONCLUSIONS

We provide evidence that household use of OP pesticides is associated with an increased risk of developing PD.

Temporal variation of residential pesticide use and comparison of two survey platforms: a longitudinal study among households with young children in Northern California

BACKGROUND

Pesticide use patterns are essential inputs into human pesticide exposure models. Currently, data included for modeling purposes have mostly been collected in cross-sectional surveys. However, it is questionable whether responses to one-time surveys are representative of pesticide use over longer periods, which is needed for assessment of health impact. This study was designed to evaluate population-wide temporal variations and within-household variations in reported residential pesticide use patterns and to compare alternative pesticide data collection methods - web surveys versus telephone interviews.

METHOD

A total of 481 households in Northern California provided up to 3 annual telephone interviews on residential pesticide use; 182 of these households provided up to 6 quarterly web surveys that covered the same topics for some of the same time periods. Information on frequency and areas of application were collected for outdoor and indoor sprays, indoor foggers, professional applications, and behind-the-neck treatments for pets. Population-wide temporal variation and within-household consistency were examined both within telephone surveys and within web surveys, and quantified using Generalized Estimating Equations and Mixed Effect Modeling. Reporting between the two methods, the telephone survey and the web survey, was also compared.

RESULTS

Use prevalence of outdoor sprays across the population reported in both the annual telephone surveys and the quarterly web surveys decreased over time, as did behind-the-neck treatment of pets reported in the quarterly web survey. Similarly, frequencies of use of these products decreased in the quarterly web surveys. Indoor sprays showed no statistically significant population-wide temporal variation in either survey. Intraclass correlation coefficients indicated consistent use within a household for behind-the-neck treatment on pets and outdoor sprays but great variability for the use of indoor sprays. Indoor sprays were most consistently applied in the bathroom and kitchen. Outdoor sprays were consistently more often applied by male household members, while indoor sprays were not. The two survey approaches obtained fairly similar results on the prevalence of using pesticides, but found discrepancies in use frequencies. In addition, the number of products purchased was positively correlated with application frequency for outdoor sprays (R = 0.51, p = 0.0005) but not for indoor sprays.

CONCLUSIONS

In this population, repeated surveys are necessary either to obtain a reliable estimate of the average household use of pesticides or to project potential temporal changes of pesticide use. Web surveys could collect comparable data to traditional telephone surveys for some information. However, researchers need to consider the internet acceptability among the target population and balance lower participant burden against the need for sufficiently accurate time-varying measurement, to improve subject retention in longitudinal surveys.

Residential pesticide usage in older adults residing in Central California

Information on residential pesticide usage and behaviors that may influence pesticide exposure was collected in three population-based studies of older adults residing in the three Central California counties of Fresno, Kern, and Tulare. We present data from participants in the Study of Use of Products and Exposure Related Behaviors (SUPERB) study (N = 153) and from community controls ascertained in two Parkinson’s disease studies, the Parkinson’s Environment and Gene (PEG) study (N = 359) and The Center for Gene-Environment Studies in Parkinson’s Disease (CGEP; N = 297). All participants were interviewed by telephone to obtain information on recent and lifetime indoor and outdoor residential pesticide use. Interviews ascertained type of product used, frequency of use, and behaviors that may influence exposure to pesticides during and after application. Well over half of all participants reported ever using indoor and outdoor pesticides; yet frequency of pesticide use was relatively low, and appeared to increase slightly with age. Few participants engaged in behaviors to protect themselves or family members and limit exposure to pesticides during and after treatment, such as ventilating and cleaning treated areas, or using protective equipment during application. Our findings on frequency of use over lifetime and exposure related behaviors will inform future efforts to develop population pesticide exposure models and risk assessment.

Residential insecticide usage in northern California homes with young children

Residential insecticide usage and actual application details were collected in a population-based sample of 477 households residing within 22 counties in northern California with at least one child of age ≤ 5 years between January 2006 and August 2008. Structured telephone interviews were conducted collecting information on residential use of insecticides, including outdoor sprays, indoor sprays, indoor foggers, applications by professionals, and pet flea/tick control during the previous year. Interviews also covered post-treatment behaviors, which influence post-application exposure levels. Altogether, 80% of the households applied some type of insecticide in the previous year, with half of this population using two or more application methods. Of the households using insecticides, half reported applying insecticides relatively infrequently (<4 times per year), whereas 11-13% reported high frequency of use (>24 times per year). Application frequency was temperature dependent, with significantly more applications during the warmer months from May through October. Spot treatments appeared to be the most prevalent application pattern for sprays. For one out of three of the indoor applications, children played in the treated rooms on the day of the application, and for 40% of the outdoor applications, pets played in the treated area on the day of the application. These findings describing the intensity of insecticide use and accompanying behaviors in families with young children may inform future insecticide exposure modeling efforts, and ultimately, risk assessments.

Effects of simultaneous repeated exposure at high levels of arsenic and malathion on hepatic drug-biotransforming enzymes in broiler chickens

Groundwater contamination with arsenic is a major global health concern. The organophosphorus insecticide malathion has gained significance as an environmental pollutant due to its widespread use in agriculture, grain storage, ectoparasite control and public health management. The deleterious effects produced by arsenic or malathion alone are documented, but very little is known about the consequences of their coexposure. The aim of the current study was to examine the effects of repeated simultaneous exposure to arsenic and malathion on drug-biotransforming enzymes in the liver of broiler chickens. One-month-old broiler chickens were exposed daily to arsenic (50 ppm)-supplemented drinking water, malathion (500 ppm)-mixed diet or in a similar fashion coexposed to these agents for 28 days. At the term, changes in body weight, organ weights, and levels of hepatic cytochrome P450 (CYP), cytochrome b(5), microsomal and cytosolic proteins; aminopyrine N-demethylase (ANDM), aniline P-hydroxylase (APH), glutathione S-transferase (GST) and uridine diphosphate glucuronosyltransferase (UGT) were assessed. Arsenic, malathion or their coexposure decreased the body weight gain and liver weight. Brain weight (relative) was increased with arsenic or malathion, but not with the coexposure. Treatment with arsenic decreased the CYP and cytochrome b(5) contents by 39 and 36%, than with malathion by 54 and 22% and the coexposure by 45 and 28%, respectively. The ANDM activity was decreased with arsenic (44%), malathion (23%) and the coexposure (32%). Arsenic (23%) and the coexposure (37%), but not malathion (14%), reduced the APH activity. The activities of hepatic microsomal and cytosolic GST were increased with all the three treatments [Arsenic (microsomal: 88% cytosolic: 113%), malathion (microsomal: 137%, cytosolic: 94%) and coexposure (microsomal: 140%, cytosolic: 148%)]. These treatments did not significantly affect the hepatic UGT activity, but reduced the hepatic microsomal (arsenic: 28%, malathion: 34% and coexposure: 43%) and cytosolic (17-19%) protein contents. The effects of coexposure on the activities of various phase I and phase II drug-biotransforming enzymes were almost similar to that of arsenic or malathion. This study provides evidence that repeated coexposure to arsenic and malathion may influence the extent of drug metabolism in chickens.

Potential exposure of children and adults to cypermethrin following use of indoor insecticide foggers

The magnitude and distribution of cypermethrin from total release, over-the-counter foggers was studied in a test room and in residences to facilitate evaluation of regulatory exposure algorithms and new human exposure assessments based upon urine biomonitoring. Surface residue (SR) was evenly distributed in a small test room (3.6 mciro g cypermethrin/cm(2)) where thorough mixing of the aerosol occurred. In a residence SR was significantly affected by room size and distance from the fogger. Air levels in the residence were as high as 30 mciro g cypermethrin/cm(3) after 4.5 h. The availability of surface residues was measured with an automated surface cotton cloth wipe and ethyl acetate extraction. Only 5% of the SR was available from nylon carpet. Tile, wood and linoleum resulted in 30, 10, and 10% of SR being available, respectively. These data are used to estimate cypermethrin exposure of children and adults for comparison with existing regulatory reference dosages and exposure assessments based upon biomonitoring.

Use and storage of domestic pesticides in the UK

Several epidemiological studies, particularly from the United States, have suggested health concerns may arise from the chronic exposure of young children to pesticides in their home environment. Most of these studies are retrospective and the available pesticide exposure information is either subject to the problem of recall or derived from surrogate information. Currently, little is known about the extent of pesticide use in homes and gardens in the UK. This was investigated in this study using a sample of parents from the Avon Longitudinal Study of Parents and Children (ALSPAC) cohort in and around Bristol. The level and extent of pesticide use by parents was explored through interviews that took place at the homes of the participants during August to November 2001, followed by an inventory of products stored in the home. From the results, 93% of parents had used at least one pesticide over the preceding year with the highest use being in the garden, second inside the home, followed by treating pets and head lice. Most households reported using one to five different products over the past year, with a mean of 3.5. The frequency of pesticide use showed that a minority of parents are using pesticides in the high frequency range. Over 85 different pesticide products were found to be stored in 76% of homes, with 76 different types of pesticide active ingredients. Insecticides were the most commonly used and stored pesticide.

Effects of subchronic malathion exposure on the pharmacokinetic disposition of pefloxacin

Malathion is one of the most extensively used organophosphorus pesticides applied in agriculture, mosquito eradication and in the control of animal ectoparasites and human body lice. The widespread use of malathion has raised concern over its potential to cause untoward health effects in humans, animals and birds. Malathion inhibits cytochrome P450 monooxygenases and has the potential to alter pharmacokinetic profiles of therapeutic agents that are metabolized in the liver. The present study was undertaken to evaluate the impact of subchronic exposure of malathion on the pharmacokinetic disposition of pefloxacin. Chickens were given either normal diet or malathion through food at a concentration of 1000ppm for 28 days. Subsequently, pefloxacin was administered either intravenously or orally (control) to birds fed normal diet and orally to malathion-exposed chickens at a dosage of 10mgkg(-1) body weight. Blood samples were drawn from the brachial vein at predetermined time intervals after drug administration. Plasma was separated and analyzed for pefloxacin by reverse-phase high performance liquid chromatography. The plasma concentration-time data were analyzed by non-compartmental techniques. Following intravenous administration of pefloxacin, elimination half-life (t(1/2β)), area under the plasma concentration-time curve (AUC) and mean residence time (MRT) were 8.2±0.7h, 66±9μghml(-1) and 10.5±1.1h, respectively, and when the drug was administered orally, the respective values of pharmacokinetic parameters were 8.2±0.4h, 31±3.1μghml(-1) and 11.7±0.6h. Malathion exposure significantly increased maximum plasma drug concentration, t(1/2β), AUC and MRT of pefloxacin to 54, 22, 117 and 37% of control, respectively. These findings provide evidence that subchronic malathion exposure markedly influences the elimination kinetics of pefloxacin which may be due to malathion-mediated inhibition of metabolism of pefloxacin.

Interactive alterations of arsenic and malathion in the disposition kinetics of pefloxacin

Assessment of deleterious effects produced by concurrent exposure to commonly encountered chemicals is of great concern to find out toxicological consequences arising as a result of their interactions and for a more comprehensive management of chemical-induced untoward effects. The naturally occurring heavy metal arsenic is present in food and water. Malathion is one of the most widely used pesticides in agriculture and public health practices worldwide. Humans, animals, and birds are exposed to these chemicals through environmental processes. Since arsenic and malathion are shown to exert an inhibitory effect on cytochrome P450 activities, their continuous exposure may alter the disposition kinetics of drugs that are predominantly metabolized hepatically. The current study was undertaken to evaluate the impact of subchronic exposure of arsenic, malathion, and their combination on the disposition kinetics of widely used fluoroquinolone antimicrobial pefloxacin in chickens. Broiler chickens were exposed to either arsenic (50 ppm), malathion (500 ppm), or arsenic (50 ppm) plus malathion (500 ppm). Arsenic and malathion were given in drinking water and feed, respectively. Following 28 days of exposure, all birds received a single oral dose of pefloxacin (10 mg/kg) and the plasma concentrations and the disposition kinetic parameters of the drug were determined. In the birds not exposed to arsenic and/or malathion, the elimination half-life (t(1/2beta)), area under the plasma concentration-time curve (AUC), maximum plasma drug concentration (C(max)), mean residence time (MRT), and bioavailability of pefloxacin were 8.46 +/- 0.24 h, 39.06 +/- 1.13 microg.h.ml(-1), 2.69 +/- 0.19 microg.ml(-1), 12.29 +/- 0.48 h, and 60.52 +/- 1.74%, respectively. Exposure to arsenic was associated with a significant increase in C(max) (4.28 +/- 0.45 microg.ml(-1)) and a nonsignificant increase in the values of AUC (48.96 +/- 2.55 microg.h.ml(-1)) and bioavailability (74.55 +/- 3.8 %) of pefloxacin. The values of AUC (51.62 +/- 4.76 microg.h.ml(-1)), t(1/2beta) (12.57 +/- 1.26 h), MRT (19.94 +/- 1.99 h), and bioavailability (78.59 +/- 7.25 %) of pefloxacin were significantly increased in malathion-exposed birds. Concomitant exposure to arsenic and malathion did not affect the disposition kinetic variables of pefloxacin. The study shows that subchronic malathion exposure significantly alters the elimination kinetics of pefloxacin. Following concurrent exposure, arsenic nullifies the malathion-induced changes in disposition kinetics of pefloxacin by possibly diminishing the cytochrome P450-catalyzed bioactivation of malathion.

Socio-demographic characteristics of UK families using pesticides and weed-killers

Pesticides are widely used in the home and garden to kill insects, weeds and other unwanted pests. There is mounting evidence that this usage may also have health consequences particularly on children. Using the ALSPAC cohort of 13,391 families with self-reported usage data up to age 4 years of the study child, the main users of pesticides appeared to be older, Caucasian, better educated, have higher incomes and more likely to own their home or to belong to non-manual social classes compared to less frequent users. There was some suggestion that different factors may affect weed-killer compared to other pesticide use. In particular, income appeared unrelated to other pesticide use. This may reflect different attitudes to indoor compared to garden applications. Alternatively, it may reflect whether the main user was the mother or the partner. Some authorities are currently encouraging domestic users to consider other non-chemical means of pest control before using pesticides. These results may help in targeting particular groups if further reductions in pesticide usage are desired. They have also helped in identifying the important confounders for adjusting future analyses on the potential health consequences of pesticides and weed-killers.

Reference values for metabolites of pyrethroid and organophosphorous insecticides in urine for human biomonitoring in environmental medicine

Pesticides are widely used throughout the world in agriculture to protect crops, and in public health to control diseases transmitted by vectors or intermediate hosts. After the prohibition of organochlorines, such as DDT, today mainly pyrethroids and organophosphorous insecticides are used. With reliable and sensitive analytical methods for detecting metabolites of organophosphorous and pyrethroid insecticides in urinary specimens of the general population several studies have been published on internal exposure to these insecticides of the population in Germany. In total, data on levels of metabolites of organophosphorous acids in urine of about 1200 children and adults have been published, as well as data on levels of pyrethroid metabolites in urine of about 2100 children and adults. In Germany, reference values for environmental pollutants related to the population are established continuously by the Human Biomonitoring Commission of the German Federal Environmental Agency, preferably based on data gained by representative studies. Reference values are defined as the 95th percentile, rounded off within the 95% confidence interval of the population studied. Since there is a need for reference values to characterise the population's exposure to organophosphates and pyrethroids, and since there are different studies available from Germany that agree quite well with data from other industrialised countries, the Commission has derived reference values from the available data, though none of the studies had fulfilled criteria on representativity. Reference values for metabolites of organophosphorous acids are as follows: DMP 135 microg/l, DMTP 160 microg/l and DEP 16 microg/l and for metabolites of pyrethroids: cis-Cl2CA 1 microg/l, trans-Cl2CA 2 microg/l and 3-PBA 2 microg/l. As the volume-related concentrations of organophosphate and pyrethroid metabolites show no significant age-dependence, the reference values derived are not age-stratified. Though based merely on statistical and not on toxicological data, levels analysed above the reference levels, when reliably measured (verified several times), should prompt environmental health practitioners to search for sources, within the bounds of proportionality. In addition to accidental poisoning, possible sources include indoor contamination following improper pest control operations in homes as well as in pets and food products contaminated by these pesticides.

Chlorpyrifos accumulation patterns for child-accessible surfaces and objects and urinary metabolite excretion by children for 2 weeks after crack-and-crevice application

The Children's Post-Pesticide Application Exposure Study (CPPAES) was conducted to look at the distribution of chlorpyrifos within a home environment for 2 weeks after a routine professional crack-and-crevice application and to determine the amount of the chlorpyrifos that is absorbed by a child living within the home. Ten residential homes with a 2- to 5-year-old child in each were selected for study, and the homes were treated with chlorpyrifos. Pesticide measurements were made from the indoor air, indoor surfaces, and plush toys. In addition, periodic morning urine samples were collected from each of the children throughout the 2-week period. We analyzed the urine samples for 3,5,6-trichloropyridinol, the primary urinary metabolite of chlorpyrifos, and used the results to estimate the children's absorbed dose. Average chlorpyrifos levels in the indoor air and surfaces were 26 (pretreatment)/120 (posttreatment) ng/m3 and 0.48 (pretreatment)/2.8 (posttreatment) ng/cm2, respectively, reaching peak levels between days 0 and 2; subsequently, concentrations decreased throughout the 2-week period. Chlorpyrifos in/on the plush toys ranged from 7.3 to 1,949 ng/toy postapplication, with concentrations increasing throughout the 2-week period, demonstrating a cumulative adsorption/absorption process indoors. The daily amount of chlorpyrifos estimated to be absorbed by the CPPAES children postapplication ranged from 0.04 to 4.8 microg/kg/day. During the 2 weeks after the crack-and-crevice application, there was no significant increase in the amount of chlorpyrifos absorbed by the CPPAES children.

Patterns of pesticide use and their determinants among wives of farmer pesticide applicators in the Agricultural Health Study

Pesticide exposure among farmers' wives is poorly characterized. Using questionnaire data from a cohort study of licensed pesticide applicators and their spouses, we investigated patterns of pesticide use among farmers' wives (n = 31,173). Wives reported a wide range of pesticide use: 36% never used pesticides during their lifetimes, whereas the heaviest pesticide users (10%) reported lifetime use of 3 or more agricultural pesticides plus commonly used residential pesticides. We identified 5 ordinal pesticide-use categories and studied factors associated with each category through polytomous logistic regression. Engaging in field work and household hygiene practices that could increase exposure were associated with pesticide use, and associations appeared to strengthen with increasing pesticide use category. Farm women reporting the heaviest pesticide use could exacerbate their exposure by engaging in practices that could increase pesticide contact.

Seasonal pesticide use in a rural community on the US/Mexico border

An environmental measurement and correlation study of infant and toddler exposure to pesticides was carried out in a colonia south of the city of Laredo, Texas. As part of the study, homes were visited during the late spring or summer, and during the winter of 2000-2001. At each visit, families reported on their use of pesticides in and around the home and floor wipe samples were collected and analyzed for 14 organophosphate and triazine pesticides. Selection of homes was based on the presence of infants and toddlers. A total of 27 homes participated in both seasonal visits. The interval between visits was 6 +/- 1.4 months. Univariate and multivariate nonparametric analyses were carried out using SPSS statistical software. Pesticide use within the home was more often reported than outside use and showed seasonal variation in use patterns. Indoor use was primarily associated with ants and cockroaches, and secondarily with rodents. The primary room treated was the kitchen, and the primary structures treated were the floors, lower walls, and dish cupboards. Seasonal variations were not found in the use of pesticides used outside the home and outdoor use was primarily associated with ant control. Based on parent reports, most pesticides used in the homes were pyrethroids. Several of the pesticides measured in floor wipe samples, Azinphos methyl, Fonofos, and Simazine, also showed seasonal variations. However, these pesticides are used in agriculture and were not associated with reported house and yard use patterns.

An update of the epidemiology of non-Hodgkin's lymphoma

The incidence of non-Hodgkin's lymphoma (NHL) has increased approximately 80% since the 1970s, and is now the fifth most common cancer in the United States. The incidence of NHL is approximately 50% higher among men than women and 35% higher among white people than black people. The incidence rates of all subtypes of NHL have increased, especially diffuse large-cell and immunoblastic subtypes. Extranodal NHL has increased more rapidly than nodal NHL. The overall NHL incidence rates stabilized in the early 1990s and then began to decrease between 1996 and 2000, resulting in part from a decrease in the incidence of AIDS. The incidence of NHL types not associated with AIDS and NHL in groups at low risk of AIDS has continued to increase throughout the 1990s. The increasing incidence of NHL is poorly understood. Improved diagnostic techniques, the effects of the human immunodeficiency virus epidemic, and immunosuppressive therapies accounted for only one third of the increase. Increase in NHL may be attributed to immunodeficiency, various infections, familial aggregation, blood transfusion, genetic susceptibility to NHL, diet, and chemical exposures to pesticides and solvents. Some studies also suggest that associations between risk factors and specific NHL subtypes may be stronger than associations between the same risk factors and NHL in aggregate. Future epidemiologic studies should incorporate the new World Health Organization classification of NHL and new techniques such as cytogenetic molecular analyses to identify subtype-specific etiologic factors. Evaluation of polymorphisms in genes involved in immune function, inflammation, and the activation or detoxification of environmental and occupational chemicals is also warranted.

Current internal exposure to pesticides in children and adolescents in Germany: urinary levels of metabolites of pyrethroid and organophosphorus insecticides

AIM

Pesticides are widely used throughout the world, in agriculture to protect crops and in public health to control diseases transmitted by vectors or intermediate hosts. After the prohibition of organochlorines such as DDT, today, mainly pyrethroids and organophosphorus insecticides are used. Whereas many studies have been published on background exposure of the population to organochlorines, data on internal exposure of the population to pyrethroids and organophosphorus insecticides are scarce. Here, we report on internal exposure of children and young people, in an urban area in Germany, to pyrethroids and organophosphorus acids, assessed by the analysis of urinary levels of their corresponding specific metabolites.

METHODS

Approximately 673 children and adolescents took part in this voluntary investigation, including 331 children <6 years of age. Their parents stated that they and their children had never used pyrethroids or organophosphorus acids in their homes or for medical reasons. We analysed their spot urine samples for six metabolites of organophosphorus insecticides [dimethyl-phosphate (DMP), diethyl-phosphate (DEP), dimethyl-thiophosphate (DMTP), diethyl-thiophosphate (DETP), dimethyl-dithiophosphate (DMDTP) and diethyl-dithiophosphate (DEDTP)] and for four metabolites of pyrethroids [cis-3-(2,2-dibromo-vinyl)-2,2-dimethyl-cyclopropane carboxylic acid (Br2CA), cis-3-(2,2-dichloro-vinyl)-2,2-dimethyl-cyclopropane carboxylic acid (cis-Cl2-CA ), trans-3-(2,2-dichloro-vinyl)-2,2-dimethyl-cyclopropane carboxylic acid (trans-Cl2-CA) and 4-fluoro-3-phenoxy-benzoic acid (F-PBA)] using gas chromatographic methods with mass-selective detection. The limit of detection was 0.1-0.2 microg/l for pyrethroid metabolites and 1 microg/l for metabolites of organophosphorus acids; in DMP it was 5 microg/l.

RESULTS

The 95th percentiles of the urinary metabolite concentrations were, in microgrammes per litre, DMP 158, DMTP 180, DMDTP 12, DEP 17, DETP 8, DEDTP <1; Br2CA 0.30, cis-Cl2-CA 0.44, trans-Cl2-CA 1.22, F-PBA 0.30. There were no correlations between urinary metabolite levels and the age of the children.

CONCLUSION

Current background levels of internal exposure to pyrethroids and organophosphorus insecticides in children and adolescents in Germany are shown. Exposure to these substances in the general population is thought to occur mainly via residues in the diet. The level of background internal pyrethroid exposure in the children is orders of magnitude lower than the corresponding acceptable daily intake (ADI) values published, but the level of internal organophosphate exposure may reach and even exceed ADI values. This observation demands further investigation.

Nondietary ingestion of pesticides by children in an agricultural community on the US/Mexico border: preliminary results

An environmental measurement and correlation study of nondietary ingestion of pesticides was carried out in a colonia in south Texas. The purpose of the study was to evaluate young children's exposure to environmental levels of organophosphate (OP) pesticides in the household. Samples were collected to measure levels of OP pesticides in housedust and on children's hands. These, in turn, were compared to levels of OP pesticide metabolites in urine. A total of 52 children, 25 boys and 27 girls, participated in the spring and summer of 2000. The children were 7-53 months of age at the time of recruitment. Univariate and multivariate regression analyses were carried out using SAS statistical software. Seventy-six percent of housedust samples and 50% of hand rinse samples contained OP pesticides. All urine samples had at least one metabolite and over 95% had at least two metabolites above the limit of detection (LOD). Total OP loadings in the housedust ranged from nondetectable (nd) to 78.03 nmol/100 cm(2) (mean=0.15 nmol/100 cm(2); median=0.07 nmol/100 cm(2)); total OP loadings on the children's hands ranged from nd to 13.40 nmol/100 cm(2) (mean=1.21 nmol/100 cm(2); median=1.41 nmol/100 cm(2)), and creatinine corrected urinary levels (nmol/mol creatinine) of total OP metabolites ranged from 3.2 to 257 nmol/mol creatinine (mean=42.6; median 27.4 nmol/mol creatinine). Urinary metabolites were inversely associated with the age of the child (in months) with the parameter estimate (pe)=-2.11, P=0.0070, and 95% confidence interval -3.60 to -0.61. The multivariate analysis observed a weak association between concentrations of OP pesticides in housedust, loadings in housedust, and concentration on hands, hand surface area, and urinary levels of OP metabolites. However, hand loadings of OP pesticides were more strongly associated (r(2)=0.28; P=0.0156) with urinary levels of OP metabolites (pe=6.39; 95% CI 0.98-11.80). This study's preliminary findings suggest that surface loadings of pesticides, on hands, are more highly correlated with urinary bioassays and, therefore, may be more useful for estimation of exposure in epidemiologic studies than levels of pesticides in housedust.

Increased T-lymphocyte dependent antibody production in female SJL/J mice following exposure to commercial grade malathion

The organophosphate pesticide, malathion, was evaluated for effects on immune function in female SJL/J mice. Commercial grade malathion was dissolved in corn oil and administered at doses of 0.018-180 mg/kg to mice via oral gavage on alternate days for 28 days. Exposure to malathion did not alter brain acetylcholinesterase activity, body weight gain, organ/body weight ratios or food and water consumption during the treatment period. Malathion enhanced the primary IgM antibody response to sheep red blood cells (SRBCs) by approximately 150% (P<0.02) at all doses tested when the response was expressed per 10(6) viable spleen cells and per spleen. B-lymphocyte blastogenesis induced by lipopolysaccharide (LPS, P=0.10) was not affected by malathion exposure. T-lymphocyte blastogenesis induced by concanavalin A (ConA, P=0.23) and phytohemagglutinin (PHA-P, P=0.24) also was unaffected by treatment with malathion. Malathion had no effect on splenic macrophage phagocytosis (P>0.11). These results indicate that repeated oral administration of commercial-grade malathion increased antibody production following immunization with a T-lymphocyte dependent antigen at doses as low as 0.018 mg/kg, which is below the human allowable daily intake (0.02 mg/kg). These changes occurred in the absence of B- or T-lymphocyte hyper responsiveness or alterations in macrophage phagocytosis. Immune system alterations at a sub-clinical level following exposure to a commercial formulation of malathion may have an important impact on human and animal health risk assessment. Therefore, further investigation into the mechanisms responsible for the increased antibody production is warranted.

Metabolites of organophosphorous insecticides in urine specimens from inhabitants of a residential area

The most frequently used pesticide in U.S. homes, as well as in schools and day care centers, is chlorpyrifos. In 1998, this insecticide was detected in household dust from the former U.S. Forces housing estates in Frankfurt am Main, Germany, resulting from its earlier use up to 1993, i.e., at least 4 years ago. This led to great concern in the new inhabitants. To investigate their internal exposure to the substance, they were offered the opportunity of taking part in biomonitoring examinations. Children playing on the floor were assumed to be especially at risk due to increased exposure to chlorpyrifos via oral or dermal intake. A total of 1146 inhabitants took part in this voluntary investigation. All of them stated that they had never used chlorpyrifos in their homes. Spot urine samples of the study participants were analyzed for six metabolites of organophosphorous insecticides [dimethylphosphate (DMP), diethylphosphate (DEP), dimethylthiophosphate (DMTP), diethylthiophosphate (DETP), dimethyldithiophosphate (DMDTP), and diethyldithiophosphate (DEDTP)] using a very sensitive gas chromatographic method with mass-selective detection and a limit of detection of 1 microg/L. No evidence was found of increased internal exposure due to former chlorpyrifos application in these homes (>4 years ago), either in children or in adults. The median values and 95th percentiles of the urinary metabolite concentrations in 484 adults were (microg/g creatinine): DMP, 15.5 and 102.5; DMTP, 13.5 and 125.8; DMDTP, <1 and 13.1; DEP, 2.1 and 11.6; DETP, <1 and 6.4; DEDTP, both <1. The urinary metabolite concentrations in children <6 years of age were higher; this was caused mainly by lower creatinine concentrations. To conclude, no increase in internal exposure due to former indoor application of chlorpyrifos could be found, and the reference values published for internal organophosphate exposure in adults in Germany were confirmed. However, as shown in other environmental studies, the urinary excretion of organophosphorous metabolites exceeds dietary intake several fold; this has been estimated from the data in various duplicate dietary studies. This observation calls for further investigation.

Additive inhibitory action of chlorpyrifos and polycyclic aromatic hydrocarbons on acetylcholinesterase activity in vitro

This study tested the hypothesis that the inhibition of acetylcholinesterase is greater when the insecticide chlorpyrifos (CPF) is in the presence of several polycyclic aromatic hydrocarbons (PAHs) found in house dust. CPF-oxon (CPFO) inhibition curves of purified AChE (electric eel) were generated in the presence or absence of different concentrations of the PAHs pyrene, benzo(a)pyrene, anthracene, and fluoranthene. Without CPF-oxon, all four PAHs themselves inhibited AChE activity with IC50 values in the range 8.2-17 microM. The IC50 for benzo(a)pyrene with human recombinant AChE was 1.5 microM. When AChE was incubated with CPF-oxon together with the PAHs, the inhibitory effect on AChE was additive. This was exemplified by large (60-80%) and significant (P<0.01) inhibition in AChE activity by the PAHs when combined with nanomolar concentrations of CPF-oxon. Kinetic studies indicated that benzo(a)pyrene inhibited AChE in a noncompetitive manner, and the reduction in maximal velocity (Vmax) by benzo(a)pyrene and CPFO together was the sum of the inhibitory effect of the two inhibitors alone, further supporting an additive effect. These data suggest that some PAHs have anticholinesterase activity, and contribute in an additive manner to the inhibitory effect of CPFO on AChE in vitro. Further research is needed to determine the toxicological relevance of these findings.

Evaluation of methods for monitoring the potential exposure of small children to pesticides in the residential environment

A nine-home pilot study was conducted to evaluate monitoring methods in the field that may be used to assess the potential exposures of children aged 6 months to 5 years to pesticides found in the home environment. Several methods, some of which were newly developed in this study, were tested for measuring pesticide residues in indoor air, carpet dust, outdoor soil, and on the children's hands. Information was also collected on household characteristics, pesticides used and stored at the residence, and children's activities. Pesticides were detected at all nine study homes. With the exception of one home, at least one pesticide was detected in all matrices sampled at each house. Of the 30 target pesticides, 23 were detected during the study. The most frequently detected pesticides were chlordane, chlorpyrifos, dieldrin, hepatachlor, and pentachlorophenol. The greatest number of pesticides and highest concentrations were found in carpet dust. The results of these investigations will be discussed in terms of performance of the methods and the distribution of pesticides across the various media sampled.

Effects of subchronic parathion administration on sodium salicylate excretion kinetics in female rats

Organophosphorus (OP) pesticides are considered to be environmental contaminants, and chronic exposure to low levels through the diet may affect drug action. To study this possible interaction, ethyl parathion was administered by intubation to female rats for 35 consecutive days at a dose of 0.05 or 0.2 mg/kg of body weight per day. At 7, 21 and 35 days after parathion was initiated, rats were administered a single dose of 20 mg/kg sodium salicylate intraperitoneally. Total salicylates, salicylic acid (SA), salicyluric acid (SU) and gentisic acid (GA) were determined in urine. At 7 days, parathion treatment slowed the excretion of total salicylates. This effect was more evident at longer treatment times. Total excretion of SA was increased at the expense of GA at 7 days. However, this effect was reversed at 21 and 35 days. Excretion of SU was drastically diminished after 21 days of treatment with parathion. The results suggest that subchronic oral administration of parathion to female rats changes the excretion kinetics of sodium salicylate through combined effects on renal excretion mechanisms and biotransformation processes. Thus, exposure to low concentrations of environmental contaminants may produce important changes in drug action.

Tolerance to anticholinesterase compounds in mammals

Administration of multiple, sublethal doses of organophosphorus insecticides induces the development of tolerance to their toxicity. Among the different hypotheses investigated to explain the mechanism of this phenomenon, the one which has received the greatest experimental support is a downregulation of the muscarinic cholinergic receptors. Subsensitivity to cholinergic agonist has been demonstrated in vivo and in vitro in isolated organ preparations. Receptor binding experiments using muscarinic antagonists and agonists revealed a decrease of cholinergic receptors in central and peripheral tissues. Tolerance to another class of acetylcholinesterase inhibitors, carbamates has also been demonstrated. Differences from and similarities to organophosphate tolerance are discussed.