Acute health effects of organophosphorus pesticides on Tanzanian small-scale coffee growers

Acute health effects of organophosphorus (OP) pesticides on coffee farmworkers in 1991-1992 in Tanzania are reported to provide a basis for concern over farmworkers being overexposed during application. Workers exposed to OP pesticides (N=133) were drawn from a population of about 240,000 coffee farmers. They were interviewed on symptoms and personal protection, and their erythrocyte acetylcholinesterase (AChE) activity was determined during both spraying and nonspraying period. AChE activities during spraying and nonspraying period were comparable (mean 32.0, SD 7.8 vs. 33.0, SD 8.7 U/g HgB, P=0.26). The prevalence of cough, headache, abdominal pain, excessive sweating, nausea, excessive salivation, diarrhea, and vomiting did not differ significantly between spraying and nonspraying periods. There was no suggestion of decreased AChE in exposed subjects who complained of OP-related symptoms compared to symptomless exposed subjects. Use of gloves, long boots, head cover, face cover, and coverall was not significantly associated with AChE activity. No marked AChE depression was found during spraying season, which may explain the lack of association between symptoms and AChE. The fact that only moderately toxic OP pesticides were used may indicate that toxicity was not sufficiently high to cause depression. Experience, however, suggests that occupational poisoning remains a potential serious danger in coffee cultivation in Tanzania.     

Knowledge, attitude and practices of pesticide use and acetylcholinesterase depression among farm workers in Nepal

Assessing erythrocyte acetylcholinesterase (AChE) activity in farm workers across agricultural seasons can be used to monitor risks of pesticide exposure. We surveyed a total of 403 households in Nepal and adopted the Test-mate ChE Cholinesterase Test System to monitor AChE activity across season on the 127 individuals of the sampled households. The study aims to (i) document knowledge and practices of pesticide use among farmers and (ii) present the relationship between farmers' reported acute health symptoms and erythrocyte acetylcholinesterase depression. We found low levels of pesticide use hygiene and high levels of individuals' knowledge on the local environmental impacts of pesticide use. Safety measures taken against potential risks of pesticides exposure were inadequate. Exposure to organophosphates significantly reduced AChE activity across season, but was not sufficient enough to claim clinical symptoms whereas exposure to the pyrethroid insecticides and fungicides were sufficient enough to claim acute symptoms of poisoning.     

Neurotoxicity among pesticide applicators exposed to organophosphates.

OBJECTIVES--An epidemiological study of 90 male pesticide applicators licensed in New York was conducted to investigate the effect of exposure to organophosphate pesticides on the peripheral nervous system. METHODS--A cohort of farmers and pesticide applicators from New York State were questioned off season (November 1988-February 1989) and again during the spraying season (April 1989-August 1989) about the presence of several acute signs and symptoms. Short term exposure was validated by measuring the concentration of dimethylthiophosphate (DMTP), a metabolite of guthion, in urine. Chronic signs of subtle peripheral nerve damage were determined by vibration threshold sensitivity of the farmers and applicators tested during November 1988-February 1989 and compared with controls drawn from the general population who were tested during the same time period the next year (November 1989-February 1990). Vibration threshold sensitivity was determined for both the hands and feet. Long term exposure to pesticides was determined by questionnaire. RESULTS--Paired t tests show that mean vibration threshold scores were significantly higher for the dominant (P < 0.00) and non-dominant (P < 0.04) hands among pesticide applicators when compared with scores for population based controls individually matched on age, sex, and county of residence. CONCLUSIONS--A significant increase in mean vibration threshold sensitivity for the dominant and non-dominant hand suggests previous organophosphate exposure among pesticide applicators was associated with a loss of peripheral nerve function.     

Occupational exposure to pesticides and nerve conduction studies among Korean farmers

This study aimed to determine whether occupational exposure to pesticides was associated with decreased nerve conduction studies among farmers. On 2 separate occasions, the authors performed a cross-sectional study of a group of 31 male farmers who periodically applied pesticides. The study included questionnaire interviews and nerve conduction studies on the median, ulnar, posterior tibial, peroneal, and sural nerves. Although all mean values remained within laboratory normal limits, significant differences between the first and second tests were found in sensory conduction velocities on the median and sural nerves, and motor conduction velocities on the posterior tibial nerve. Lifetime days of pesticide application was negatively associated with nerve conduction velocities at most nerves after adjusting for potential confounders. These findings may reflect a link between occupational pesticide exposure and peripheral neurophysiologic abnormality that deserves further evaluation.     

Effects of pesticides on the peripheral and central nervous system in tobacco farmers in Malaysia: studies on peripheral nerve conduction, brain-evoked potentials and computerized posturography

We examined the effects of pesticides on the central and peripheral nervous system in the setting of a tobacco farm at a developing country. Maximal motor and sensory nerve conduction velocities (MCV and SCV, respectively) in the median, sural and tibial nerves, postural sway, and brain-evoked potentials (auditory event-related and visual-evoked potentials) were measured in 80 male tobacco farmers and age- and sex-matched 40 controls in Kelantan, Malaysia. Median SCV (finger-wrist) in farmers using Delsen (mancozeb, dithiocarbamate fungicide), who showed significant decrease of serum cholinesterase activities, were significantly lower compared with the controls. Sural SCV in farmers using Fastac (alpha-cypermethrin, pyrethroid insecticide) and median MCV (elbow-wrist) in farmers using Tamex (butralin, dinitroaniline herbicide) were significantly slowed compared with their respective controls. In Delsen (mancozeb, dithiocarbamate) users, the power of postural sway of 0-1 Hz was significantly larger than that in the controls both in the anterior-posterior direction with eyes open and in the right-left direction with eyes closed. The former type of sway was also significantly increased in Tamaron (methamidophos, organophosphorus insecticide) users. In conclusion, nerve conduction velocities and postural sway seem to be sensitive indicators of the effects of pesticides on the central and peripheral nervous system.     

Assessment of the exposure of pest control operators to organophosphorus pesticides. Organophosphorus pesticides in blood and alkyl phosphate metabolites in urine

Pest control operators usually spray pesticides in small areas such as a kitchen in a restaurant and are exposed to various pesticides, especially those of the organophosphorus (OP) type. In order to evaluate their occupational exposure to OP pesticides during the work, OP pesticides in blood and alkyl phosphate metabolites in urine of these operators were analyzed and the relationship between pesticide exposure and analytical results were studied. OP pesticides in blood were analyzed by gas chromatography with flame photometric detector (FPD-GC) after separation of phospholipid in blood with silicagel column chromatography. OP pesticides were not detected in any blood samples (the limit of detection was 1 ng/ml). Dimethylphosphate (DMP) and dimethylthiophosphate (DMTP), being urinary metabolites of OP pesticides, were analyzed by FPD-GC after benzyl derivatization. This method eliminated interfering peaks in gas chromatograms. The ratio of two isomeric derivatives of DMTP was found to be constant. Both DMP and DMTP of the exposed group were significantly higher than those of the non-exposed group, DMP being higher than DMTP. The ratio of DMP to DMTP in the fenitrothion-dichlorvos-exposed group was significantly higher than that in the fenitrothion-exposed group. It was considered that the ratio might reflect a result of pesticide exposure. The urinary metabolites of OP pesticides tended to become lower with the lapse of time since the last exposure. However, small amounts were detected in a few samples even 5 days after the last exposure.     

Neurobehavioural effects among workers occupationally exposed to organophosphorous pesticides

Aims: To identify neurobehavioural deficits among workers exposed to organophosphorous (OP) pesticides in their occupation. Methods: This study was conducted during the period when pesticides were applied to cotton crops in the fields in Menoufiya Governorate, Egypt. Fifty two occupationally exposed male workers were compared to 50 unexposed male controls who were similar in age, socioeconomic class, and years of education (⩾12 years). All participants completed a questionnaire (assessing personal, occupational, and medical histories), general and neurological clinical examination, neurobehavioural test battery (including tests for verbal abstraction, problem solving, attention, memory, and visuomotor speed), personality assessment, and serological analysis for serum acetylcholinesterase. Results: After correcting for confounders of age and education, the exposed participants exhibited significantly lower performance than controls on six neurobehavioural tests (Similarities, Digit Symbol, Trailmaking part A and B, Letter Cancellation, Digit Span, and Benton Visual Retention). A longer duration of work with pesticides was associated with lower performance on most neurobehavioural tests after adjusting for multiple comparisons. Although serum acetylcholinesterase was significantly lower in the exposed than the control participants, it was not significantly correlated with either neurobehavioural performance or neurological abnormalities. Conclusions: Occupational exposure to OP pesticides was associated with deficits in a wider array of neurobehavioural functions than previously reported, perhaps because of higher exposure in this population. Moderate chronic OP exposure may not only affect visuomotor speed as reported previously, but also verbal abstraction, attention, and memory.     

Effect of pesticide exposure on acetylcholinesterase activity in subsistence farmers from Campeche, Mexico

The authors surveyed agricultural production methods and pesticide use among subsistence farmers (campesinos) in 4 rural communities of Campeche, Mexico. Self-reports of symptoms of poisoning resulting from occupational pesticide exposure were elicited by questionnaire (N = 121), and acetylcholinesterase (AChE) activity during insecticide use was evaluated from blood samples (N = 127). In individuals from 2 of the 4 communities, AChE activity was significantly lower (p < 0.05) than the mean of activity determined for individuals in a reference group. Results of this study show that erythrocyte AChE inhibition provides a good biomarker of exposure to organophosphate pesticides in field studies with human populations. Carbamates, particularly carbofuran, seem to be more associated with exuberant and diversified symptomatology of pesticide exposure than organophosphates. Studies in field communities where both carbamates and organophosphates are suspected to exist should include blood AChE determinations, symptomatology surveys, and socioeconomic questionnaires. The authors recommend that the Mexican National Health Ministry authorities specify additional provisions regarding the use of protective equipment and the adoption of other safety practices during field work, increase information campaigns about the risks of pesticide use and the value of safety practices, and increase programs of medical monitoring and assistance for rural communities dealing with pesticides.     

混配农药施药员的生物监测

目的 探讨混配农药中的拟除虫菊酯对有机磷抑制红细胞乙酰胆碱酯酶（AChE）作用的影响。方法 在江苏和山东省随机选择1周内未接触任何农药的健康施药员作为生物监测对象,其中,混配农药组（简称混配组）65人,使用甲胺磷与溴氰菊酯（江苏省）或甲基对硫磷与氯氰菊酯（山东省）混配的农药;单一农药组（简称单一组）67人,使用甲胺磷（江苏省）或甲基对硫磷（山东省）。喷药时间为2h,其个人防护等外部条件均与本地平常情况一致。同时在当地乡镇卫生院随机选择未接触农药的健康医务人员2人为对照组。使用硫代乙酰胆碱二硫代双硝基苯甲酸（DTNB）分光光度法,分别测定喷药前、喷药后即刻和喷药后1h的红细胞AChE活力。结果 喷药后混配组和单一组的红细胞AChE活力均受到抑制,与喷药前相比差异有高度显著性（P＜0．01）;红细胞AChE活力的喷药后即刻抑制率和喷药后1h恢复率,混配组均高于单一组,但差异均无显著性（t=－0．9270,df=64.1,P=0.3574;t=-1.3413,df=64.3,P=0.1845)。结论 本次监测未观察到混配农药中的拟除虫菊酯对有机磷抑制红细胞AChE活力的作用有明显影响。     

Biochemical and electrophysiological study of subjects with a history of past lead exposure

The effects of lead on porphyrin metabolism and peripheral nervous system were studied in a group of 38 subjects who had not been exposed for a period of time, ranging from 3 to 27 years. The mean values for blood lead (PbB), chelated lead(PbUEDTA), and free erythrocyte protoporphyrin (FEP) were found to be significantly higher in the subjects with past lead exposure than in controls. In all cases the neurological examination was negative. The mean values for maximum motor conduction velocity (MMCV) and conduction velocity of the slower fibers (CVSF) of the ulnar and peroneal nerves were found to be significantly lower in the subjects with past lead exposure than in the control group of 23 subjects standardized for age. Signs of partial denervation were present in four cases, with two presenting a decrease of the motor conduction velocity (MCV) as well. No correlation was found between electrophysiological findings and biochemical indicators of dose and effect. The length of exposure showed a significant negative correlation only with the MMCV of the ulnar nerve. A significant difference from controls standardized for age was observed only in subjects with exposure of more than 6 months for all the electromyographic (EMG) parameters. It does not appear that the EMG findings could depend upon modest lead deposits still present in the organism; they should rather give evidence to the permanent effect of alterations that occurred during the prolonged exposure to lead.     

Temporal association of children's pesticide exposure and agricultural spraying: report of a longitudinal biological monitoring study

We measured organophosphorus (OP) pesticide exposures of young children living in an agricultural community over an entire year and evaluated the impact of agricultural spraying on exposure. We also examined the roles of age, sex, parental occupation, and residential proximity to fields. We recruited 44 children (2-5 years old) through a Women, Infants, and Children clinic. We collected urine samples on a biweekly basis over a 21-month period. Each child provided at least 16 urine samples, and most provided 26. We analyzed samples for the dialkylphosphate (DAP) metabolites common to the OP pesticides. DAP concentrations were elevated in months when OP pesticides were sprayed in the region's orchards. The geometric means of dimethyl and diethyl DAPs during spray months were higher than those during nonspray months (p = 0.009 for dimethyl; p = 0.018 for diethyl). Dimethyl DAP geometric means were 0.1 and 0.07 micro mol/L for spray months and nonspray months, respectively (57% difference); diethyl DAP geometric means were 0.49 and 0.35, respectively (40% difference). We also observed differences for sex of the child, with male levels higher than female levels (p = 0.005 for dimethyl; p = 0.046 for diethyl). We observed no differences due to age, parental occupation, or residential proximity to fields. This study reports for the first time the temporal pattern of pesticide exposures over the course of a full year and indicates that pesticide spraying in an agricultural region can increase children's exposure in the absence of parental work contact with pesticides or residential proximity to pesticide-treated farmland.     

Electroencephalogram, cognitive state, psychological disorders, clinical symptom, and oxidative stress in horticulture farmers exposed to organophosphate pesticides

The aim of this paper was to study the toxicity of organophosphate (OP) pesticides in exposed farmers for electroencephalography, cognitive state, psychological disorders, clinical symptom, oxidative stress, acetylcholinesterase, and DNA damage. A comparative cross-sectional analysis was carried out in 40 horticulture farmers who were exposed to OPs in comparison to a control group containing 40 healthy subjects with the same age and sex and education level. Lipid peroxidation (LPO), superoxide dismutase (SOD), catalase, glutathione peroxidase, DNA damage, total antioxidant capacity (TAC), total thiol molecules, and acetylcholinesterase (AChE) activity were measured in the blood of subjects. Clinical examination and complete blood test were undertaken in order to record any abnormal sign or symptoms. Cognitive function, psychological symptoms, and psychological distress were examined and recorded. Comparing with controls, the farmers showed higher blood levels of SOD and LPO while their TAC decreased. Farmers showed clinical symptoms such as eczema, breathing muscle weakness, nausea, and saliva secretion. Regarding cognitive function, the orientation, registration, attention and calculation, recall, and language were not significantly different in farmers and controls. Among examinations for psychological distress, only labeled somatization was significantly higher in farmers. The present findings indicate that oxidative stress and inhibition of AChE can be seen in chronically OP-exposed people but incidence of neuropsychological disorders seems a complex multivariate phenomenon that might be seen in long-term high-dose exposure situations. Use of supplementary antioxidants would be useful in the treatment of farmers.     

Occupational asthma symptoms and respiratory function among aerial pesticide applicators

BACKGROUND: Pesticide exposure has been suggested as one causal factor for the rise in asthma prevalence. The goal of this investigation was to determine the effect of pesticide exposure on respiratory symptoms and lung function in workers with occupational exposure to pesticides. METHODS: A prospective, case-controlled study was conducted among pesticide aviators (AV) and community controls (Con). In Phase I, subjects completed an asthma survey and baseline spirometry. In Phase II, subjects reported symptoms, lung function monitoring, and pesticide exposure during two, 14-day periods. RESULTS: Phase I-Self-reported asthma and symptoms were similar among AV (n = 135) and Con (n = 118) with 4-6% prevalence reported but with higher rates among smokers. Baseline lung function was similar; although, a higher proportion of AV had forced expiratory volume in one second (FEV(1)) <80% predicted (8% vs. 2%, P = 0.02). Phase II-Self-reported symptoms were similar with 80% of AV (n = 50) and 73% of Con (n = 49) reporting no symptoms. Only 4% of AV and 6% of controls reported increased symptoms from baseline to spray season. Serial lung function did not differ between group and mean diurnal variation in peak expiratory flow improved in both groups between sampling times (AV 18% vs. 14%; Con 19% vs. 16%, P < 0.001). CONCLUSIONS: This study suggests that among workers with occupational pesticide exposure, asthma symptoms and lung function are similar to those of controls with only community-based exposure.     

Dietary intake and its contribution to longitudinal organophosphorus pesticide exposure in urban/suburban children

BACKGROUND: The widespread use of organophosphorus (OP) pesticides has led to frequent exposure in adults and children. Because such exposure may cause adverse health effects, particularly in children, the sources and patterns of exposure need to be studied further. OBJECTIVES: We assessed young urban/suburban children's longitudinal exposure to OP pesticides in the Children's Pesticide Exposure Study (CPES) conducted in the greater Seattle, Washington, area, and used a novel study design that allowed us to determine the contribution of dietary intake to the overall OP pesticide exposure. METHODS: Twenty-three children 3-11 years of age who consumed only conventional diets were recruited for this 1-year study conducted in 2003-2004. Children switched to organic diets for 5 consecutive days in the summer and fall sampling seasons. We measured specific urinary metabolites for malathion, chlorpyrifos, and other OP pesticides in urine samples collected twice daily for a period of 7, 12, or 15 consecutive days during each of the four seasons. RESULTS: By substituting organic fresh fruits and vegetables for corresponding conventional food items, the median urinary metabolite concentrations were reduced to nondetected or close to non-detected levels for malathion and chlorpyrifos at the end of the 5-day organic diet intervention period in both summer and fall seasons. We also observed a seasonal effect on the OP urinary metabolite concentrations, and this seasonality corresponds to the consumption of fresh produce throughout the year. CONCLUSIONS: The findings from this study demonstrate that dietary intake of OP pesticides represents the major source of exposure in young children.     

Cytogenetic monitoring in a population occupationally exposed to pesticides in Ecuador

We analyzed the incidence of structural and numerical chromosomal aberrations (CAs) in workers of a plantation of flowers located in Quito, Ecuador, in South America. This study included 41 individuals occupationally exposed to 27 pesticides, some of which are restricted in many countries and are classified as extremely toxic by the World Health Organization; among these are aldicarb and fenamiphos. The same number of individuals of the same age, sex, and geographic area were selected as controls. Workers exposed to these pesticides showed an increased frequency of CA compared with control group (20.59% vs. 2.73%; p < 0.001). We conclude that screening for CA is an adequate biomarker for evaluating and detecting genotoxicity resulting from exposure to pesticides. Levels of erythrocyte acetylcholinesterase were also determined as a complementary metabolic study. Levels below the optimal (> 28 U/mL blood) were found in 88% of exposed individuals; this clearly shows the effect of organophosphate pesticides. When comparing the levels of acetylcholinesterase and structural CA frequencies, there was a negative linear correlation (r = 0.416; p < 0.01). We conclude that by using both analyses it may be possible to estimate damage produced by exposure to organophosphate pesticides.     

The recovery of plasma cholinesterase and erythrocyte acetylcholinesterase activity in workers after over-exposure to dichlorvos

Plasma cholinesterase and erythrocyte acetylcholinesterase activities have a long history of use in monitoring both workers at risk of organophosphorus pesticide (OP) exposure and in investigating accidental exposures to OPs. On account of wide inter-individual variation, the establishment of unexposed, baseline enzyme activities is necessary for accurate interpretation. This paper describes the rate of recovery of the two enzymes' activity after substantial over-exposure of eight subjects to the OP dichlorvos. Plasma cholinesterase activity, immediately after exposure, was substantially more inhibited than erythrocyte acetylcholinesterase activity. The plasma enzyme activity showed an exponential pattern of recovery with a half-life of around 12 days, so recovery was essentially complete after about 50 days. This reported half-life of recovery is consistent with the reported de novo synthesis rate of plasma cholinesterase. The mean recovery of erythrocyte acetylcholinesterase activity appeared linear over time, attaining unexposed activity after about 82 days, which is somewhat shorter than the life-span of erythrocytes. These indicate the sort of time period, after an OP incident, before a valid unexposed level can be established in an individual; and substantiate the guidance given in the Health & Safety Executive's document MS17 on a minimum period of 60 days without exposure in order to establish pre-exposure baseline levels.     

Pesticide exposure alters follicle-stimulating hormone levels in Mexican agricultural workers

Organophosphorous pesticides (OPs) are suspected of altering reproductive function by reducing brain acetylcholinesterase activity and monoamine levels, thus impairing hypothalamic and/or pituitary endocrine functions and gonadal processes. Our objective was to evaluate in a longitudinal study the association between OP exposure and serum levels of pituitary and sex hormones. Urinary OP metabolite levels were measured by gas-liquid chromatography, and serum pituitary and sex hormone levels by enzymatic immunoassay and radioimmunoassay in 64 men. A total of 147 urine and blood samples were analyzed for each parameter. More than 80% of the participants had at least one OP metabolite in their urine samples. The most frequent metabolite found was diethylthiophosphate (DETP; 55%), followed by diethylphosphate (DEP; 46%), dimethylthiophosphate (DMTP; 32%), and dimethyldithiophosphate (DMDTP; 31%). However, the metabolites detected at higher concentrations were DMTP, DEP, DMDTP, and dimethylphosphate. There was a high proportion of individuals with follicle-stimulating hormone (FSH) concentrations outside the range of normality (48%). The average FSH serum levels were higher during the heavy pesticide spraying season. However, a multivariate analysis of data collected in all periods showed that serum FSH levels were negatively associated with urinary concentrations of both DMTP and DMDTP, whereas luteinizing hormone (LH) was negatively associated with DMTP. We observed no significant associations between estradiol or testosterone serum levels with OP metabolites. The hormonal disruption in agricultural workers presented here, together with results from experimental animal studies, suggests that OP exposure disrupts the hypothalamic-pituitary endocrine function and also indicates that FSH and LH are the hormones most affected.     

对氧磷酶和谷胱甘肽S转移酶基因多态性与农药暴露花卉种植者的健康关系研究

目的 探讨花卉种植者(花农)对氧磷酶及谷胱甘肽S转移酶基因多态性的分布情况,并分析基因多态性与健康的关系.方法 选择云南省某村136名从事花卉种植的花农作为暴露组(男性74名,女性62名);41名不使用农药的同村居民作为对照组(男性16名,女性25名);进行问卷调查和体格检查,并采集血液样本,分析血常规、肝功能、激素水平、免疫球蛋白(IgM、IgG、IgA)和全血乙酰胆碱酯酶活性.采用聚合酶链反应-限制性片段长度多态性方法(PCR-RFLP)检测PON1-107、PON1 192、GST M1、T1基因型.结果 (1)对照组球蛋白高于暴露组(β=-0.16,t=-2.30,P=0.02),而白蛋白与球蛋白的比(白球比)低于暴露组(β=0.14,t=2.09,P=0.04);(2)PON1 192位点分析显示,QQ基因型个体症状积分高于RR基因型个体(t=-2.78,P=0.006);(3)GSTT1-的个体分析显示,球蛋白高于GSTT1+的个体(β=-0.20,t=-3.01,P=0.00),IgG高于GST T1+的个体(β=-0.15,t=-2.15,P=0.03),而白球比低于GST T1+的个体(β=0.17,t=2.54,P=0.01);(4)农药暴露者心电图异常情况增加(β=1.147,P=0.042).结论 PON1 192和GST T1位点与农药暴露后的花农健康状况相关.     

Effect of Pesticide Exposure on Acetylcholinesterase Activity in Subsistence Farmers from Campeche,Mexico

The authors surveyed agricultural production methods and pesticide use among subsistence farmers (campesinos) in 4 rural communities of Campeche, Mexico. Self-reports of symptoms of poisoning resulting from occupational pesticide exposure were elicited by questionnaire (N = 121), and acetylcholinesterase (AChE) activity during insecticide use was evaluated from blood samples (N = 127). In individuals from 2 of the 4 communities, AChE activity was significantly lower (p < 0.05) than the mean of activity determined for individuals in a reference group. Results of this study show that erythrocyte AChE inhibition provides a good biomarker of exposure to organophosphate pesticides in field studies with human populations. Carbamates, particularly carbofuran, seem to be more associated with exuberant and diversified symptomatology of pesticide exposure than organophosphates. Studies in field communities where both carbamates and organophosphates are suspected to exist should include blood AChE determinations, symptomatology surveys, and socioeconomic questionnaires. The authors recommend that the Mexican National Health Ministry authorities specify additional provisions regarding the use of protective equipment and the adoption of other safety practices during field work, increase information campaigns about the risks of pesticide use and the value of safety practices, and increase programs of medical monitoring and assistance for rural communities dealing with pesticides.     

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.