A longitudinal approach to assessing urban and suburban children's exposure to pyrethroid pesticides

We conducted a longitudinal study to assess the exposure of 23 elementary school-age children to pyrethroid pesticides, using urinary pyrethroid metabolites as exposure biomarkers. We substituted most of the children's conventional diets with organic food items for 5 consecutive days and collected two daily spot urine samples, first morning and before bedtime voids, throughout the 15-day study period. We analyzed urine samples for five common pyrethroid metabolites. We found an association between the parents' self-reported pyrethroid use in the residential environment and elevated pyrethroid metabolite levels found in their children's urine. Children were also exposed to pyrethroids through their conventional diets, although the magnitude was smaller than for the residential exposure. Children's ages appear to be significantly associated with pyrethroids exposure, which is likely attributed to the use of pyrethroids around the premises or in the facilities where older children engaged in the outdoor activities. We conclude that residential pesticide use represents the most important risk factor for children's exposure to pyrethroid insecticides. Because of the wide use of pyrethroids in the United States, the findings of this study are important for both children's pesticide exposure assessment and environmental public health.     

Farm children's exposure to herbicides: comparison of biomonitoring and questionnaire data

BACKGROUND: Pesticide exposure has been associated with various childhood cancers. However, most studies rely on questionnaires, with few using biologic measures of dose. This study was designed to measure herbicide exposure directly in children of farm applicators, and to compare these results with exposure imputed from questionnaire information. METHODS: Two consecutive 24-hour urine samples were collected from 92 children of Ontario farm applicators who used the herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) or MCPA (4-chloro-2-methylphenoxyacetic acid) for the first time during 1996. The farm applicator completed questionnaires describing his pesticide-handling practices as well as the child's location during the various stages of handling these pesticides. RESULTS: Approximately 30% of the children on farms using these herbicides had detectable concentrations in their urine, with maximum values of 100 microg/L for 2,4-D and 45 microg/L for MCPA. Children with higher levels were more likely to be boys and to have parents who also had higher mean urinary concentrations. The sensitivity and specificity of a simple indicator of use were 47% and 72%, respectively, for 2,4-D, and 91% and 30%, respectively, for MCPA, using the biomonitoring data as the gold standard. CONCLUSIONS: Information on living on a farm, or on living on a farm where a specific pesticide is used, is not enough to classify children's exposures. Given this potential for misclassification, we urge incorporation of biomonitoring studies in subsets of children at least to estimate the extent of misclassification.     

Health costs from short-term exposure to pesticides in Nepal

Household surveys were undertaken every week for seven months in 2005 to understand acute health symptoms and to estimate health costs associated with pesticide exposure in rural Nepal. The cost-of-illness and avertive action approach was used to estimate costs of pesticide use. The probit regressions fit sickness and avertive actions with exposure to pesticides and other factors. Based on data from 291 households, the study finds that the magnitude of exposure to insecticides and fungicides significantly influenced the occurrence of acute symptoms. The predicted probability of falling sick from pesticide-related symptoms is significantly higher among individuals who apply pesticides compared to individuals in the same household who are not directly exposed. Further, the predicted annual cost of illness as a result of pesticide use is estimated to be Nepalese Rupees 144 per individual. This cost is nearly one-third of the total expenditure on health care services, but is small compared to the increase in farm production costs, thus when faced with a choice between the health care costs and increases in farm production costs, the individual opts for pesticides. However, the costs are nearly eight times higher compared to the population who were not directly exposed. This study suggests that there are acute health impacts of pesticide use; however, because of the low level of the health costs, farm workers may underestimate the effects of pesticides on the human being, and thus they may continue to use pesticides without any safety precautions.     

Organic diets significantly lower children's dietary exposure to organophosphorus pesticides

We used a novel study design to measure dietary organophosphorus pesticide exposure in a group of 23 elementary school-age children through urinary biomonitoring. We substituted most of children's conventional diets with organic food items for 5 consecutive days and collected two spot daily urine samples, first-morning and before-bedtime voids, throughout the 15-day study period. We found that the median urinary concentrations of the specific metabolites for malathion and chlorpyrifos decreased to the nondetect levels immediately after the introduction of organic diets and remained nondetectable until the conventional diets were reintroduced. The median concentrations for other organophosphorus pesticide metabolites were also lower in the organic diet consumption days; however, the detection of those metabolites was not frequent enough to show any statistical significance. In conclusion, we were able to demonstrate that an organic diet provides a dramatic and immediate protective effect against exposures to organophosphorus pesticides that are commonly used in agricultural production. We also concluded that these children were most likely exposed to these organophosphorus pesticides exclusively through their diet. To our knowledge, this is the first study to employ a longitudinal design with a dietary intervention to assess children's exposure to pesticides. It provides new and persuasive evidence of the effectiveness of this intervention.     

Measurement of children's exposure to pesticides: analysis of urinary metabolite levels in a probability-based sample.

The Minnesota Children's Pesticide Exposure Study is a probability-based sample of 102 children 3-13 years old who were monitored for commonly used pesticides. During the summer of 1997, first-morning-void urine samples (1-3 per child) were obtained for 88% of study children and analyzed for metabolites of insecticides and herbicides: carbamates and related compounds (1-NAP), atrazine (AM), malathion (MDA), and chlorpyrifos and related compounds (TCPy). TCPy was present in 93% of the samples, whereas 1-NAP, MDA, and AM were detected in 45%, 37%, and 2% of samples, respectively. Measured intrachild means ranged from 1.4 microg/L for MDA to 9.2 microg/L for TCPy, and there was considerable intrachild variability. For children providing three urine samples, geometric mean TCPy levels were greater than the detection limit in 98% of the samples, and nearly half the children had geometric mean 1-NAP and MDA levels greater than the detection limit. Interchild variability was significantly greater than intrachild variability for 1-NAP (p = 0.0037) and TCPy (p < 0.0001). The four metabolites measured were not correlated within urine samples, and children's metabolite levels did not vary systematically by sex, age, race, household income, or putative household pesticide use. On a log scale, mean TCPy levels were significantly higher in urban than in nonurban children (7.2 vs. 4.7 microg/L; p = 0.036). Weighted population mean concentrations were 3.9 [standard error (SE) = 0.7; 95% confidence interval (CI), 2.5, 5.3] microg/L for 1-NAP, 1.7 (SE = 0.3; 95% CI, 1.1, 2.3) microg/L for MDA, and 9.6 (SE = 0.9; 95% CI, 7.8, 11) microg/L for TCPy. The weighted population results estimate the overall mean and variability of metabolite levels for more than 84,000 children in the census tracts sampled. Levels of 1-NAP were lower than reported adult reference range concentrations, whereas TCPy concentrations were substantially higher. Concentrations of MDA were detected more frequently and found at higher levels in children than in a recent nonprobability-based sample of adults. Overall, Minnesota children's TCPy and MDA levels were higher than in recent population-based studies of adults in the United States, but the relative magnitude of intraindividual variability was similar for adults and children.     

Predicting postnatal mental disorder with a screening questionnaire: a prospective cohort study from Zimbabwe

BACKGROUND: Postnatal mental disorders are common causes of morbidity but are rarely diagnosed or treated in busy primary care clinics in developing countries. OBJECTIVE: To determine whether a brief psychiatric screening questionnaire used in the 8th month of pregnancy can predict postnatal mental disorder. STUDY DESIGN: Prospective cohort study. SITE: A peri-urban settlement in Zimbabwe. POPULATION: 500 women in the 8th month of pregnancy identified by traditional birth attendants and primary care clinics. SAMPLE: "High risk" cohort consisted of all women who scored 8 or more on the Shona Symptom Questionnaire (SSQ), an indigenous psychiatric questionnaire (n = 95). Low risk cohort consisted of 105 women randomly selected from the remainder of the sampling frame. OUTCOME MEASURE: Revised Clinical Interview Schedule at six to eight weeks postpartum; scores of 14 or more indicate psychiatric caseness. RESULTS: The prevalence of postnatal mental illness was 16%. Odds ratios (95% confidence intervals) for high risk women becoming cases in the postnatal period were 10.6, 4.8, 23.9, p < 0.0001 after adjustment for age, marital status, and occupation. CONCLUSIONS: A brief method of detecting women at high risk of developing a postnatal mental disorder can be used with reasonable accuracy in the 8th month of pregnancy. Further research is needed to determine whether interventions applied to this high risk group can reduce their postnatal morbidity.

 

     

Use of biomarkers to indicate exposure of children to organophosphate pesticides: implications for a longitudinal study of children's environmental health

Because of their history of widespread use in the United States and unknown long-term health effects, organophosphate pesticides (OPs) are being considered as a chemical class of interest in planning for the National Children's Study, a longitudinal study of children's environmental health. The availability and appropriate use of biomarkers to determine absorbed doses of environmental chemicals such as OPs are critical issues. Biomarkers of OP exposure are typically measured in blood and urine; however, postpartum meconium has been shown to be a promising matrix for assessing cumulative in utero exposure to the fetus, and studies are currently in progress to determine the utility of using saliva and amniotic fluid as matrices. In this article, we discuss the advantages and disadvantages of the currently available OP exposure monitoring methods (cholinesterase inhibition in blood, pesticides in blood, metabolites in urine and alternative matrices); study design issues for a large, long-term study of children's environmental health; and current research and future research needs. Because OPs are rapidly metabolized and excreted, the utility of one-time spot measurements of OP biomarkers is questionable unless background exposure levels are relatively stable over time or a specific time frame of interest for the study is identified and samples are collected accordingly. Biomarkers of OP exposure can be a valuable tool in epidemiology of children's environmental health, as long as they are applied and interpreted appropriately.     

Neuropsychologic effects of long-term exposure to pesticides: results from the French Phytoner study

The Phytoner study investigated a possible association between neuropsychologic performances and long-term exposure to pesticides in Bordeaux vineyard workers, most of whom use fungicides. Among the 917 subjects interviewed from February 1997 to August 1998, 528 were directly exposed to pesticides through mixing and/or spraying (mean exposure duration: 22 years), 173 were indirectly exposed through contact with treated plants, and 216 were never exposed. All subjects performed neuropsychologic tests administered at home by trained psychologists. The risk of scoring a low performance on the tests was constantly higher in exposed subjects. When taking into account educational level, age, sex, alcohol consumption, smoking, environmental exposures, and depressive symptoms and when restricting analysis to subgroups, results remained significant for most tests, with odds ratios (OR) exceeding 2. These results point to long-term cognitive effects of low-level exposure to pesticides in occupational conditions. Given the frequency of pesticide use and the potential disabilities resulting from cognitive impairments, further toxicologic and epidemiologic research is needed to confirm these results and assess the impact on public health.     

A tiered approach for assessing children's exposure

Recently, intense attention has been given to children's health issues, particularly in the use of consumer products. Because of this attention, researchers have been planning and initiating studies specifically aimed at developing both toxicology data and exposure data directed to improve our understanding of industrial and consumer product chemical impacts on children's health. To ensure that this research is focused on the highest priority chemicals, we present a methodology for determining and prioritizing the higher hazard chemicals and scenarios for which children could be disproportionately or highly exposed. This tiered approach includes a screening step for initial chemical selection, a hazard assessment based on no- or lowest-observed-adverse-effect levels, and a margin of exposure (MOE) calculation. The initial chemical screen focuses on the chemical presence in specific media that are special to children, such as foods children regularly eat and drink, residential or school air, products children use, and soil and dust in and around residences. Data from the literature or from models serve as the initial exposure estimate. This methodology would allow us to focus on those chemicals to which children are most exposed that are also associated with, potentially, the highest risk. Use of the MOE calculation allows for comparison among chemicals, prioritization of chemicals for evaluation and testing, and identification of significant data gaps.     

Changes in juvenile coho salmon electro-olfactogram during and after short-term exposure to current-use pesticides

For anadromous salmonids, olfaction is a critical sense, enabling return migration. In recent years, several pesticides have been identified that interfere with salmonid olfaction at concentrations in the microg/L range; thus, they may pose a risk to species longevity. In the present study, we investigated the acute effects of five agricultural pesticides on juvenile coho salmon (Oncorhynchus kisutch) olfaction using the electro-olfactogram (EOG), a measure of odorant-evoked field potentials. Electro-olfactogram responses to the odorant L-serine were measured during and following a 30-min exposure of the left olfactory rosette to chlorothalonil, endosulfan, glyphosate acid, iodocarb (IPBC), trifluralin, and 2,4-dichlorophenoxyacetic acid. With the relatively insoluble pesticides endosulfan and trifluralin, decreases in EOG amplitude were only apparent at relatively high concentrations (100 and 300 microg/L, respectively) following 20 min of exposure and were absent for chlorothalonil (1 mg/L). With the water-soluble herbicide glyphosate, significant EOG reductions occurred within 10 min of exposure to 1 mg/L and more rapidly with higher concentrations. Recovery of EOG post-glyphosate exposure was concentration-dependent, and complete recovery was not observed with some concentrations at 60 min postexposure. Dichlorophenoxyacetic acid only affected EOG at high concentration (100 mg/L), where it eliminated EOG within 2 min of exposure. With IPBC, EOG was decreased at 25 min of exposure to 1 microg/L; higher concentrations caused decreases to occur more rapidly. Excluding IPBC and glyphosate, all EOG reductions occurred at concentrations greater than the current Canadian water-quality guidelines and reported 96-h lethality values. Our results show that olfactory neurons can be impaired rapidly by some current-use pesticides, even at exposures in the low-microg/L range.     

Occupational exposure to cholinesterase inhibiting pesticides: a Greek case

The determination of plasma or serum cholinesterase is absolute and it is considered as a reliable index of exposure in workers of organophosphorus pesticides industries. In the present study the plasma cholinesterase of 28 persons working in the packaging of an ortho-thio-phosphate was determined, before and after their exposure to this agent. The results of this study showed a plasma cholinesterase depression of 37%, a decrease which was statistically significant (P<0.001).     

Suresight视力筛查仪对婴幼儿视力筛查结果分析

目的对常规保健的0~3岁儿童开展视力筛查,寻找0~3岁儿童屈光发育规律,筛查高危人群,早期发现儿童眼病和视力问题。方法采用Suresight手持式视力筛查仪对进行正常体检的0~3岁散居儿童进行视力筛查。计数资料比较采用χ~2检验,P0.05为差异有统计学意义。结果 0~3岁各年龄段儿童均可配合筛查,共进行筛查3 318名,其中异常553例,筛查异常阳性率为16.67%,男童、女童视力筛查异常分别出现295例(16.76%)、258例(16.56%),差异无统计学意义(P0.05);0岁组与1岁组,1岁组与2岁组、3岁组比较,差异有统计学意义(均P0.01);2岁与3岁组比较差异无统计学意义(P0.05)。结论应用Suresight视力筛查仪在0~3岁婴幼儿中开展视力筛查,早期发现高危可疑人群,采取不同的管理干预措施,对儿童眼保健工作有直接指导意义。     

Leukemia and non-Hodgkin's lymphoma in childhood and exposure to pesticides: results of a register-based case-control study in Germany

Previous studies have suggested an association between exposure to pesticides and different types of childhood cancer. This paper presents results from a population-based case-control interview study of parents of children less than 15 years of age, which was conducted in the states of West Germany from 1993 to 1997. Cases were 1,184 children with leukemia, 234 with non-Hodgkin's lymphoma, and 940 with a solid tumor; 2,588 controls were also included. Parental occupational exposures were found to be related to childhood cancer regardless of the time period of exposure and the type of cancer. This finding might partially be explained by different recall of past exposures by the parents of cases and controls. Residential use of insecticides was associated with childhood lymphoma: both extermination of insects by professional pest controllers (odds ratio (OR) = 2.6, 95% confidence interval (CI): 1.2, 5.7) and frequency of parental use of household insecticides (p for trend = 0.02) were significant risk factors for this diagnosis. The use of pesticides on farms was weakly related to childhood leukemia (OR = 1.5, 95% CI: 1.0, 2.2), while their use in gardens was not associated with childhood leukemia (OR = 1.0, 95% CI: 0.8, 1.2). The major strengths of this study were the population base and the large number of cases and controls included; a drawback was assessment of exposure on the basis of parental interviews. The data provide some evidence for an increased leukemia risk for children living on farms and for an association between use of household pesticides and risk of childhood leukemia or lymphoma.     

Multiple myeloma and exposure to pesticides: a Canadian case-control study

The objective of this study was to investigate the putative associations of specific pesticides with multiple myeloma. A matched, population-based, case-control study was conducted among men residing in six Canadian provinces (Quebec, Ontario, Manitoba, Saskatchewan, Alberta, and British Columbia). Data were collected on 342 multiple myelome cases and 1506 age and province of residence matched controls. Data were collected by mailed questionnaires to capture demographic characteristics, antecedent medical history, detailed lifetime occupational history, smoking history, family history of cancer, and exposure to broadly characterized pesticides at home, work, and practicing hobbies. Details of pesticide exposures were collected by telephone interview for those who reported 10 hours or more per year of exposure. Exposure to pesticides grouped into major chemical classes resulted in increased risk being detected only for carbamate insecticides [odds ratio (OR) and 95% confidence interval (CI) 1.90 (1.11, 3.27) adjusted for potential confounders]. An exposure to fungicide captan [2.35 (1.03, 5.35)] was positively associated with the incidence of multiple myeloma. While an exposure to carbaryl [1.89 (0.98, 3.67)] was associated with the incidence of multiple myelome with borderline significance. The authors further suggest that certain pesticide exposures may have a role in multiple myeloma etiology, and identify specific factors warranting investigation in other populations.     

Estimation of long-term exposure to pesticides

Quantifying the exposure of agricultural workers to pesticides is difficult in the face of the heterogeneity of the pesticides used, the variability in methods of application, and the lack of adequate exposure data. This report describes an attempt to estimate long-term dermal and inhalation exposure of bulb farmers by the development of an exposure index. This proposed exposure index consists of generic levels of exposure specific to the method of application, which were derived from databases as well as from field studies. The index is further determined by farm-related parameters such as acreage and number of pesticide applications ascertained from questionnaire responses. A widely used dithiocarbamate mixture served as a marker compound for exposure to other pesticides. Ranking of 127 bulb farmers according to calculated lifetime dermal exposure correlated only moderately to ranking based on duration of exposure, e.g., years of exposure and farm acreage. This finding indicates that the proposed exposure index could provide a useful estimate of long-term exposure to a mixture of pesticides in epidemi-ological investigations.