Exposure of commercial pesticide applicators to the herbicide alachlor

Evaluation of Dermal Exposure to the Herbicide Alachlor Among Vegetable Farmers in Thailand

Vegetable farmers applying the herbicide alachlor may be highly exposed through dermal contact when spraying. Dermal patches were attached to 10 locations on the farmers' skin when they mixed and applied alachlor in vegetable farming areas in Thailand. Measurements were made on farmers using either a backpack sprayer with a 2 stroke gasoline motor and fan or a battery operated pump. Forty-seven vegetable farmers in Bungphra subdistrict of Thailand participated in this study. Both motorized and battery pump backpack sprayers wearing long-sleeve shirts had significantly lower alachlor concentrations on the dermal patches under their long-sleeve shirts compared to those who wore only short-sleeve shirts, regardless of the sprayer type. Moreover, sprayers wearing long pants had significantly lower alachlor concentrations on dermal patches placed under the pants on the lower legs than those wearing short pants, regardless of the sprayer type. The highest estimated alachlor exposures were found on the upper legs (median = 9.29 µg/h) for those using a 2 stroke engine/fan backpack sprayer and on the lower legs (2.87 µg/h) for those using the battery operated pump backpack sprayer. The estimated total body alachlor exposures of applicators using the 2 stroke engine/fan backpack sprayer (219.48 µg/h) were significantly higher than those using the battery operated pump backpack sprayer (15.50 µg/h). Using long-sleeve shirts as personal protection reduced alachlor exposures for the arms 97-99% and wearing long pants reduced alachlor exposure to the legs for 81-99%. Thus, training about the protection provided by clothing choices would be one step in improving the health and safety of Thai farmers.

Literature review: dermal monitoring data for pesticide exposure assessment of farm workers

OBJECTIVE

To conduct a literature review to determine the types of information that existing dermal pesticide monitoring data could provide for future pesticide exposure assessment in occupational epidemiology.

METHODS

A systematic literature search was performed on eight online databases. Two screening phases with predetermined criteria identified the qualifying literature. Standard information and dermal pesticide monitoring data were recorded and summarized from each qualifying study to assess its usefulness for future pesticide exposure assessment.

RESULTS

A total of 31 farm studies qualified for review; task information was used to standardize all farm job(s) evaluated into 5 job groups: operators, applicators, mixer-loaders, field workers, and flaggers. When attempting to compare dermal exposure levels between studies, two types of variation were identified: (1) variation in study focus and reporting and 2) variation in exposure levels. The former variation type prevented exposure level comparisons between studies. Within studies, exposure levels were compared across body parts to identify that which had the highest measured exposure and to determine if results were similar in other studies that evaluated the same farm job. Using studies that measured exposure for multiple farm jobs, within study comparisons of total body exposure were performed to evaluate work factors.

CONCLUSION

Future dermal pesticide exposure monitoring studies should standardize reporting procedures, as suggested in this review, to allow for more extensive dermal data comparisons. Body parts with highest measured levels of dermal exposure were identified by farm job, along with work factors to be further investigated as potential dermal pesticide exposure determinants for farm workers.

Environmental and biological monitoring for the identification of main exposure determinants in vineyard mancozeb applicators

Grapevine is a vulnerable crop to several fungal diseases often requiring the use of ethylenebisdithiocarbamate (EBDC) fungicides, such as mancozeb. This fungicide has been reported to have goitrogenic, endocrine disrupting, and possibly immunotoxic effects. The aim of this study was to assess workers' exposure in two scenarios of mancozeb application and analyse the main determinants of exposure in order to better understand their mechanism of influence. Environmental monitoring was performed using a modified Organisation for Economic Co-operation and Development (OECD) "patch" methodology and by hand-wash collection, while mancozeb's metabolite, ethylenethiourea (ETU), was measured in 24-h preexposure and postexposure urine samples. Liquid chromatography-mass spectrometry was used for determination of mancozeb and ETU in different kinds of samples. Closed tractor use resulted in 40 times lower potential exposure compared with open tractor. Coveralls reduced skin exposure 4 and 10 times in case of open and closed tractors, respectively. Gloves used during application resulted in 10 times lower hand exposure in open but increased exposure in closed tractors. This study has demonstrated that exposure to mancozeb is low if safe occupational hygiene procedures are adopted. ETU is confirmed as suitable biological marker of occupational exposure to mancozeb, but the absence of biological exposure limits significantly reduces the possibility to interpret biological monitoring results in occupationally exposed workers.

Total pesticide exposure calculation among vegetable farmers in Benguet, Philippines

This was a cross-sectional study that investigated pesticide exposure and its risk factors targeting vegetable farmers selected through cluster sampling. The sampling size calculated with P = .05 was 211 vegetable farmers and 37 farms. The mean usage of pesticide was 21.35 liters. Risk factors included damaged backpack sprayer (34.7%), spills on hands (31.8%), and spraying against the wind (58%). The top 3 pesticides used were pyrethroid (46.4%), organophosphates (24.2%), and carbamates (21.3%). Those who were exposed to fungicides and insecticides also had higher total pesticide exposure. Furthermore, a farmer who was a pesticide applicator, mixer, loader, and who had not been given instructions through training was at risk of having higher pesticide exposure. The most prevalent symptoms were headache (64.1%), muscle pain (61.1%), cough (45.5%), weakness (42.4%), eye pain (39.9%), chest pain (37.4%), and eye redness (33.8%). The data can be used for the formulation of an integrated program on safety and health in the vegetable industry.

Comparison of pesticide exposure and physical examination, neurological assessment, and laboratory findings between full-time and part-time vegetable farmers in the Philippines

OBJECTIVES

This study aimed to compare the work practices and health effects of pesticide exposure between full-time and part-time vegetable farmers.

METHODS

Data was gathered via structured personal interview using a 9-page questionnaire, physical examination, and blood extraction for complete blood count and serum creatinine.

RESULTS

Pyrethroid was the pesticide type most used by both groups. The risk for full-time farmers was related to both the amount of exposure and the type of pesticide. There were more full-time farmers who complained of falling ill because of work. This difference was statistically significant (P = 0.05). The level of those seeking medical attention was also significantly different between the two groups (P = 0.01). In assessing the individual components of the neurologic examination, 5.22% of full-time and 8.63% of part-time farmers had abnormal cranial nerve function, and 22 (5.7%) and 9 (6.47%) had abnormal motor strength. All farmers tested for reflexes, meningeals, and autonomics from both groups were normal. Based on hematologic examination, full-time farmers had higher mean values for creatinine, white blood cell, red blood cell, hemoglobin, and hematocrit. Activity of cholinesterase enzymes in blood can be utilized as a biomarker for the effect of organophosphates; of the 232 blood cholinesterase results, 94 (40%) were abnormal.

CONCLUSION

The study showed certain differences between full-time and part-time farmers in terms of farming practices and health-related problems. Education on safe pesticide use and handling and better health monitoring of the farmers are recommended.

Pesticide handling and exposures among cotton farmers in the gambia

OBJECTIVES

There are substantial health hazards to farmers and the environment associated with pesticide use in developing countries. Based on observations by the authors and previous reports, most previous studies in Africa are descriptive in nature. The aim of this study was to investigate how cotton farmers are exposed to pesticides in The Gambia and quantify their pesticide exposures and provide information for the formulation of a policy on pesticide safety for the country.

METHODS

A representative sample of 20 cotton farmers in the Central and Upper River Divisions (CRD and URD) of The Gambia were surveyed by questionnaires. Dermal pesticide exposures among a subset of 10 farmer/pesticide applicators were assessed by dermal patch samples, observation, and postapplication questionnaires.

RESULTS

The study revealed that a toxic organochlorine insecticide, Callisulfan (endosulfan), is frequently sprayed on cotton plants by the farmers. The farmers wore no protective equipment and were inadequately dressed for work with this pesticide. Laboratory analysis of the mixed formulation showed a wide range in the concentration of the pesticide solution among the farmer/pesticide applicators and dermal patch samples showed very high residues of endosulfan analytes on their body surfaces.

CONCLUSIONS

A low level of awareness of pesticide toxicity prevails amonsg cotton farmers in The Gambia. There is a less than adequate control of pesticides and other hazardous agrichemicals in the country.

A moving robotic hand system for whole-glove permeation and penetration: captan and nitrile gloves

The aim of this study was to develop a robotic hand to test the influence of hand movement on the permeation/penetration of captan through disposable nitrile rubber gloves. An available robotic hand was modified to within one standard deviation of the anthropometric 50th percentile male hand. Permeation tests used a nylon inspection glove interposed between medium-size outer and inner nitrile gloves, the latter protected the hand. Permeation of an aqueous emulsion (217 mg/mL) of captan was conducted at 35 degrees C +/- 0.7 degrees C. A new surface wipe technique facilitated collection of captan from the inner surface of the exposed nitrile gloves, a technique favored above rinse methods that extracted captan from within the glove. With hand movement, the permeated mass of captan collected after 8 hr ranged from 1.6 to 970 microg (Brand A) and 8.6 +/- 1.2 microg (Brand B). Without hand movement, the corresponding masses ranged from 1.4 to 8.4 microg (Brand A) and 11 +/- 3 mg (Brand B). These results were not significantly different at p < or = 0.05 using parametric and nonparametric statistical tests but indicated that hand movement could influence the precision of permeation (F-test p < or = 0.05). One glove exhibited failure after 2 hr with movement, in comparison with 0.5 to 9.9 microg captan with no movement. Hand movement did not appear to significantly affect the permeation of captan through nitrile gloves. However, hand movement did influence physical and/or chemical degradation, resulting in glove failures. The robotic hand simulated normal hand motions, was reliable, and could be used to assess the influence of hand movement on the permeation of nonvolatile components through gloves. Future research should continue to investigate the influence of hand movement and additional work factors on the permeation, penetration, and physical integrity of protective gloves.

Cotton liners to mediate glove comfort for greenhouse applicators

Greenhouse applicators' acceptance of cotton knit gloves worn as liners under nitrile chemical-resistant gloves (CRG) for pesticide application was investigated through a wear study in Iowa and New York. Comfort was assessed by questionnaires and interviews with 10 applicators. Contamination levels of four pesticides on CRG and liners at thumb, forefinger, palm, and cuff locations were determined by chemical analysis using high-performance liquid chromatography or gas chromatography. Applicators reported feeling more comfortable with cotton liners under their CRG than without and that cotton liners were easy to manage. Contamination was significantly greater on nitrile CRG than on cotton liners underneath, but a few liner specimens had measurable contamination. No significant contamination differences were found between right- and left-hand gloves. Contamination varied significantly by hand location, with cuffs least, and by pesticide, with chlorpyrifos most. These results support the Environmental Protection Agency's recommendation that liners should be disposable, but further work on liners and their laundering feasibility seems indicated.

A method for assessing occupational pesticide exposures of farmworkers

BACKGROUND

The health of farmworkers as related to pesticide exposure is of concern but assessing exposures for epidemiologic studies requires different techniques than approaches used for studies of industrial workers.

METHODS

A review of the literature identified possible factors that affect exposure intensity. A model was developed to estimate an exposure score. Exposures in the literature were estimated using the model and compared to the measurements in the literature.

RESULTS

Three studies were found with information appropriate for evaluation of the model. There was a statistical difference between the means of the scores corresponding to above and below the median of the measurements. The correlation coefficient between the scores and the measurements from the literature was 0.77.

CONCLUSIONS

Although the evaluation was limited, the model appeared to work well, but more testing is needed. More research is also needed to increase understanding of what affects the exposures of these workers.

An evaluation of the feasibility of using cytogenetic damage as a biomarker for alachlor exposure

Alachlor is a widely used herbicide for which there is significant human exposure, principally through groundwater contamination and inhalation. Because alachlor is purported to be carcinogenic and mutagenic, we initiated studies to determine if induced cytogenetic damage could be used as a biomarker for exposure to this herbicide. Both isolated and whole blood human lymphocytes were exposed to alachlor using several protocols. The lymphocytes were cultured for analysis of sister chromatid exchange (SCE), chromosome aberrations (CAs), micronuclei (MN) in cytochalasin B-induced binucleated cells, and proliferation kinetics using the replicative index (RI). In addition, CD rats were injected with either 10 or 50 mg kg-1 of alachlor, 2-chloro-N-(2,6-diethylphenyl) acetamide (CDEPA) or 2, 6-diethylanaline (DEA). After 24 h, the peripheral blood lymphocytes were removed and cultured for SCE and RI analysis. Alachlor did induce a concentration-related increase in SCE in vitro, but neither it nor its metabolites (CDEPA or DEA) induced a significant increase in SCEs or an alteration of RI in vivo. At the highest in vitro concentration tested, alachlor induced a statistically-significant increase in MN, but no concomitant increase in CAs was seen. From analyses of our data and the literature on alachlor clastogenicity and exposure levels, we concluded that cytogenetic damage may not be an adequately sensitive marker for evaluating human exposure to alachlor.

Modulation of 2,6-dinitrotoluene genotoxicity by alachlor treatment of Fischer 344 rats

Due to its widespread use as a preemergent herbicide, alachlor has been detected as a groundwater contaminant. The procarcinogen, 2,6-dinitrotoluene (DNT), a by-product of the munitions industry and a precursor to polyurethane production, is found in the manufacturing waste stream. This study explores the effect of alachlor treatment on the bioactivation of DNT by examining urine mutagenicity, intestinal enzymes, and hepatic DNA adducts to detect changes in metabolism. Five-week-old male rats were treated daily by gavage with 50 mg/kg of alachlor for up to 5 weeks while control animals received an equal volume of peanut oil. At 1, 3, and 5 weeks following the initial alachlor dose, animals were administered p.o. 75 mg/kg DNT or DMSO. Urine was collected for 24 hr in metabolism cages. Following incubation with sulfatase and beta-glucuronidase, urines were individually concentrated by C-18 solid phase extraction, dried under N2, and prepared for bioassay in Salmonella typhimurium strain TA98 with and without metabolic activation. Urine from peanut oil- and alachlor-treated rots was not mutagenic. Even though calf thymus DNA-alachlor adducts formed in vitro, no hepatic DNA adducts were detected in vivo in these two treatment groups. Interestingly, a significant increase in excretion of mutagenic urine from DNT-treated rats was observed following 3 weeks of alachlor treatment in the absence of S9 (690 +/- 130 vs. 339 +/- 28 revertants/ml) which corresponded to increased DNT-related hepatic DNA adduct formation (5.90 +/- 0.88 adducts/10(8) nucleotides vs. 10.56 x +/- 0.59 adducts/10(8) nucleotides [relative adduct level (RAL)]). Elevation in the production of mutagenic urine from control and treated animals was linked to increases in intestinal nitroreductase and beta-glucuronidase activities; however, the only significant alachlor-related effects were an increase in small intestinal 1-week beta-glucuronidase and 5-week dehydrochlorinase activities. The increased urine mutagenicity and hepatic DNA adduct formation indicates that alachlor has a transient effect on DNT bioactivation that apparently is unrelated to intestinal bioactivation.