Derivation of single layer clothing penetration factors from the pesticide handlers exposure database

GuLF DREAM: A Model to Estimate Dermal Exposure Among Oil Spill Response and Clean-up Workers

Tens of thousands of individuals performed oil spill response and clean-up (OSRC) activities following the 'Deepwater Horizon' oil drilling rig explosion in 2010. Many were exposed to oil residues and dispersants. The US National Institute of Environmental Health Sciences assembled a cohort of nearly 33 000 workers to investigate potential adverse health effects of oil spill exposures. Estimates of dermal and inhalation exposure are required for those individuals. Ambient breathing-zone measurements taken at the time of the spill were used to estimate inhalation exposures for participants in the GuLF STUDY (Gulf Long-term Follow-up Study), but no dermal measurements were collected. Consequently, a modelling approach was used to estimate dermal exposures. We sought to modify DREAM (DeRmal Exposure Assessment Method) to optimize the model for assessing exposure to various oil spill-related substances and to incorporate advances in dermal exposure research. Each DREAM parameter was reviewed in the context of literature published since 2000 and modified where appropriate. To reflect the environment in which the OSRC work took place, the model treatment of evaporation was expanded to include vapour pressure and wind speed, and the effect of seawater on exposure was added. The modified model is called GuLF DREAM and exposure is estimated in GuLF DREAM units (GDU). An external validation to assess the performance of the model for oils, tars, and fuels was conducted using available published dermal wipe measurements of heavy fuel oil (HFO) and dermal hand wash measurements of asphalt. Overall, measured exposures had moderate correlations with GDU estimates (r = 0.59) with specific correlations of -0.48 for HFO and 0.68 for asphalt. The GuLF DREAM model described in this article has been used to generate dermal exposure estimates for the GuLF STUDY. Many of the updates made were generic, so the updated model may be useful for other dermal exposure scenarios.

Estimated exposure to glyphosate in humans via environmental, occupational, and dietary pathways: an updated review of the scientific literature

Glyphosate is one of the most widely used herbicides in the world, but it has also been the focus of discussion and restrictions in several countries since it was declared 'probably carcinogenic to humans (Group 2A)' by the International Agency for Research on Cancer in 2015. Since that time, several regulatory agencies have reviewed the public literature and guideline studies submitted for regulatory purposes and have concluded that it is not a carcinogen, and revised acceptable daily intakes (ADIs) and the reference dose (RfD) have been published. Also, restrictions on use have been lifted in many locations. Risk assessment for any pesticide requires knowledge of exposure in humans and the environment, and this paper is an update on a previous review in 2016 and includes papers published after 2016. These exposure data for air, water, bystanders, the general public, domesticated animals, pets, and applicators were combined and compared to the revised exposure criteria published by regulatory agencies. In all cases, measured and estimated systemic exposures to glyphosate in humans and animals were less than the ADIs and the RfD. Based on this large dataset, these exposures represent a de minimis risk. © 2019 Society of Chemical Industry.

Understanding skin absorption of common aldehyde vapours from exposure during hazardous material incidents

The toxic release of aldehyde vapours during a hazardous material (HAZMAT) incident primarily results in respiratory concerns for the unprotected public. However, skin absorption may be an important concurrent exposure route that is poorly understood for this scenario. This study provides experimental data on the skin absorption properties of common aldehydes used in industry, including acetaldehyde, acrolein, benzaldehyde and formaldehyde, in gaseous or vapour form using an adapted in vitro technique. Two of the four tested aldehydes were found to penetrate the skin in appreciable amounts following 30-min exposure at HAZMAT relevant atmospheric concentrations: acetaldehyde (5.29 ± 3.24 µg/cm²) and formaldehyde (3.45 ± 2.58 µg/cm²). Whereas only low levels of acrolein (0.480 ± 0.417 µg/cm²) and benzaldehyde (1.46 ± 0.393 µg/cm²) skin penetration was noted. The aldehydes demonstrated differing levels of interaction with fabric. Formaldehyde and acetaldehyde adsorbed strongly to denim, whereas benzaldehyde and acrolein displayed no sink properties. However, denim was shown to be an initial protective barrier and reduced penetration outcomes for all aldehydes. This study provides important information to assist first responders and confirms the relevance of using physicochemical properties (e.g. solubility, molecular weight, partition coefficient) to predict skin permeation potential in the absence of empirical data during HAZMAT incidents involving different types of aldehydes.

Performance of a Single Layer of Clothing or Gloves to Prevent Dermal Exposure to Pesticides

The suitability, availability, and use of protective clothing are critical factors determining the actual dermal exposure (ADE) of operators and workers to pesticides. A realistic assessment of occupational exposure to pesticides requires information about the performance of protective clothing during everyday use. In this study, the performance of clothing or gloves has been investigated based on available dermal exposure data in order to provide recommendations for default protection factors that can be used in regulatory exposure assessments. Suitable dermal exposure data from available exposure databases were collated and analysed. The data that met the selection criteria for the analysis of the performance of protective clothing comprised studies in which protective clothing like cotton coveralls, cotton clothing, polyester-cotton coveralls, Sontara coveralls, Tyvek coveralls, butyl/neoprene gloves, latex/PE/vinyl/PVC gloves, or nitrile gloves were worn. Based on available potential and ADE levels, the migration of pesticides through this protective clothing was estimated. Evaluation of exposure data showed that on average only 2.3-2.6% of the pesticides present on the outside of the clothing or gloves migrated through the garments, although there was a large variation with migration up to 99%. Forearms, legs, and chest areas of the clothing tended to have the greatest migration of pesticides. Caution is needed in the selection of the appropriate protection offered protective clothing for specific situations. This study gives valuable information on the performance of protective clothing, for use in exposure assessment and for default setting in exposure modelling, taking into account the type of clothing or gloves worn. As new data become available, it may be possible to further refine the protection factors offered by different types of clothing or gloves, particularly where a common protocol has been used.

Comparative Probabilistic Assessment of Occupational Pesticide Exposures Based on Regulatory Assessments

Implementation of probabilistic analyses in exposure assessment can provide valuable insight into the risks of those at the extremes of population distributions, including more vulnerable or sensitive subgroups. Incorporation of these analyses into current regulatory methods for occupational pesticide exposure is enabled by the exposure data sets and associated data currently used in the risk assessment approach of the Environmental Protection Agency (EPA). Monte Carlo simulations were performed on exposure measurements from the Agricultural Handler Exposure Database and the Pesticide Handler Exposure Database along with data from the Exposure Factors Handbook and other sources to calculate exposure rates for three different neurotoxic compounds (azinphos methyl, acetamiprid, emamectin benzoate) across four pesticide-handling scenarios. Probabilistic estimates of doses were compared with the no observable effect levels used in the EPA occupational risk assessments. Some percentage of workers were predicted to exceed the level of concern for all three compounds: 54% for azinphos methyl, 5% for acetamiprid, and 20% for emamectin benzoate. This finding has implications for pesticide risk assessment and offers an alternative procedure that may be more protective of those at the extremes of exposure than the current approach.

Potential dermal and inhalation exposure to imidacloprid and risk assessment among applicators during treatment in cotton field in China

Quantifying operator exposure to pesticides is a key component of the decision-making procedure for risk assessment. China is the largest cotton-planting country in the world. Dense cotton planting patterns and pesticide overuse potentially place Chinese cotton farmers at high levels of exposure risk. Using whole-body dosimetry during backpack spraying application in cotton filed, the present study monitored potential dermal and inhalation exposure to the insecticide imidacloprid. For forward spraying (when the operators walked forward), the total potential dermal and inhalation exposure was 2059mg/kg of active ingredient (ai), corresponding to 0.21% of the applied quantity of the insecticide. However, the total exposure of backward walking (188mg/kg of ai) was approximately 11 times lower than that of forward walking. The upper body parts (head, chest, back and arms) were the most exposed. The potential inhalation exposure contributed to <0.1% of the total exposure. The exposure risk to imidacloprid inherent in these agricultural procedures was evaluated by margin of exposure values and was found to be safe under the present cotton treatment scenarios. In general, similar body exposure and distribution between Allura Red and imidacloprid verify Allura Red's feasibility as an environmentally friendly pesticide surrogate for exposure assessment.

Operator dermal exposure and protection provided by personal protective equipment and working coveralls during mixing/loading, application and sprayer cleaning in vineyards

The efficiency of a working coverall combined with personal protective equipment to protect operators against dermal exposure to plant protection products under field conditions was studied. Operators wore a non-certified water-repellent finish polyester/cotton coverall plus a certified gown during the mixing/loading and the cleaning phases. Insecticide foliar application to a vineyard was selected as the exposure scenario. The overall dermal residue levels measured in this study were in the range of data recently collected in Europe. The water-repellent finish working coverall reduced body exposure by a factor of approximately 95%. Wearing a Category III Type 3 partial body gown during mixing/loading and cleaning of the application equipment led to a further protective effect of 98.7%. The combination of a water-repellent finish working coverall and partial body protection during specific tasks provided satisfactory levels of protection and can be considered as suitable protection for the conditions of use studied.

Comparison of latex body paint with wetted gauze wipes for sampling the chemical warfare agents VX and sulfur mustard from common indoor surfaces

Comparison of solvent-wetted gauze with body paint, a peelable surface sampling media, for the sampling of the chemical warfare agents VX and sulfur mustard from nine surfaces was performed. The nine surfaces sampled are those typical of interior public venues and include smooth, rough, porous, and non-porous surfaces. Overall, solvent-wetted gauze (wipes) performed better for the recovery of VX from non-porous surfaces while body paint (BP) performed better for the porous surfaces. The average percent VX recoveries using wipes and BP, respectively, are: finished wood flooring, 86.2%, 71.4%; escalator handrail, 47.3%, 26.7%; stainless steel, 80.5%, 56.1%; glazed ceramic tile, 81.8%, 44.9%; ceiling tile, 1.77%, 13.1%; painted drywall 7.83%, 21.1%; smooth cement, 0.64%, 10.3%; upholstery fabric, 24.6%, 23.1%; unfinished wood flooring, 9.37%, 13.1%. Solvent-wetted gauze performed better for the recovery of sulfur mustard from three of the relatively non-porous surfaces while body paint performed better for the more porous surfaces. The average percent sulfur mustard recoveries using wipes and BP, respectively, are: finished wood flooring, 30.2%, 2.97%; escalator handrail, 4.40%, 4.09%; stainless steel, 21.2%, 3.30%; glazed ceramic tile, 49.7%, 16.7%; ceiling tile, 0.33%, 11.1%; painted drywall 2.05%, 10.6%; smooth cement, 1.20%, 35.2%; upholstery fabric, 7.63%, 6.03%; unfinished wood flooring, 0.90%, 1.74%.

Farmers' Exposure to Pesticides: Toxicity Types and Ways of Prevention

Synthetic pesticides are extensively used in agriculture to control harmful pests and prevent crop yield losses or product damage. Because of high biological activity and, in certain cases, long persistence in the environment, pesticides may cause undesirable effects to human health and to the environment. Farmers are routinely exposed to high levels of pesticides, usually much greater than those of consumers. Farmers’ exposure mainly occurs during the preparation and application of the pesticide spray solutions and during the cleaning-up of spraying equipment. Farmers who mix, load, and spray pesticides can be exposed to these chemicals due to spills and splashes, direct spray contact as a result of faulty or missing protective equipment, or even drift. However, farmers can be also exposed to pesticides even when performing activities not directly related to pesticide use. Farmers who perform manual labor in areas treated with pesticides can face major exposure from direct spray, drift from neighboring fields, or by contact with pesticide residues on the crop or soil. This kind of exposure is often underestimated. The dermal and inhalation routes of entry are typically the most common routes of farmers’ exposure to pesticides. Dermal exposure during usual pesticide handling takes place in body areas that remain uncovered by protective clothing, such as the face and the hands. Farmers’ exposure to pesticides can be reduced through less use of pesticides and through the correct use of the appropriate type of personal protective equipment in all stages of pesticide handling.

Environmental fate and dietary exposures of humans to TCDD as a result of the spraying of Agent Orange in upland forests of Vietnam

The fate and transport of 2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD) released into the environment of South Vietnam (SVN) as a consequence of the aerial application of the herbicidal defoliant Agent Orange (AO) were simulated for a generic upland forest scenario and followed over a 50-year period (1965, 1968 and 1970 onwards). Modeled concentrations of TCDD in the environment were then used as inputs to a human exposure model, which focused on long-term exposures via the food chain. Intake rates and body burdens of TCDD were estimated for adult males over the course of the simulation period and compared to available biomonitoring data. One of the most important factors determining the magnitude of the simulated human exposure to TCDD was the fraction of the chemical deposited directly to soil (where it was assumed to have a degradation half-life of 10 or 15years) relative to the fraction assumed to remain on/in the forest canopy following the spray application (where it was assumed to have a degradation half-life of ≤48h). The simulated body burdens under the various scenarios considered were broadly consistent with the biomonitoring data from SVN collected in the mid-1980s to late 1990s. Taken together, the modeling results and empirical data suggest that highly elevated exposures to TCDD (i.e., body burdens in the several 100s of pg/g lipid range and greater) were not common among people inhabiting upland forest locations in SVN sprayed with AO and that peak and average body burdens were broadly similar to those of the general population of the U.S. in the 1970s and early 1980s. The model-based assessment is consistent with the 'hot spot' hypothesis i.e., potential exposures to TCDD linked to activities conducted on or near former bases where AO was stored are greater than potential exposures in areas subjected to aerial spraying.

Handler, bystander and reentry exposure to TCDD from application of Agent Orange by C-123 aircraft during the Vietnam War

Using validated models and methods routinely employed by pesticide regulatory agencies, the absorbed dosages of Agent Orange (AO) herbicide contaminant 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were estimated for mixer/loaders, applicators, and individuals in the vicinity of applications of AO by C-123 aircraft during the Vietnam War. Resulting dosages of TCDD were then transformed to estimates of adipose residues, and compared to population biomonitoring of known mixer/loaders and applicators as well as ground troops in Vietnam and civilians in the U.S. Results demonstrate that mixer/loaders and applicators had the greatest exposures and their measured residues of TCDD in adipose were consistent with the estimated exposures. Further, the potentially exposed ground troops, including those who could have been directly sprayed during aerial defoliation, had measured adipose residues that were consistent with those in civilian U.S. populations with no defined source of exposure exposures and both of those cohorts had orders of magnitude less exposure than the mixer/loaders or applicators. Despite the availability of validated exposure modeling methods for decades, the quantitative TCDD dose estimates presented here are the first of their kind for the Vietnam conflict.

Potential Dermal Exposure to Flonicamid and Risk Assessment of Applicators During Treatment in Apple Orchards

Exposure and risk assessments of flonicamid for applicators were performed in apple orchards in Korea. Fifteen experiments were done with two experienced applicators under typical field conditions using a speed sprayer. In this study, cotton gloves, socks, masks, and dermal patches were used to monitor potential dermal exposure to flonicamid, and personal air samplers with XAD-2 resin and glass fiber filter were used to monitor potential inhalation exposure. The analytical methods were validated for the limit of detection, limit of quantitation, reproducibility, linearity of the calibration curve, and recovery of flonicamid from various exposure matrices. The results were encouraging and acceptable for an exposure study. The applicability of XAD-2 resin was evaluated via a trapping efficiency and breakthrough test. During the mixing/loading, the average total dermal exposure was 22.6 μg of flonicamid, corresponding to 4.5×10(-5)% of the prepared amount. For the spraying, the potential dermal exposure was 9.32 mg, and the ratio to applied amount was 1.9 × 10(-2%). The primary exposed body parts were the thigh (2.90 mg), upper arm (1.75 mg), and lower leg (1.66 mg). By comparison, absorbable quantity of exposure was small, only 1.62 μg (3.2×10(-6)%). The margin of safety (MOS) were calculated for risk assessment, in all sets of trials, MOS > 1, indicating the exposure level of flonicamid was considered to be safe in apple orchards. Although this was a limited study, it provided a good estimate of flonicamid exposure for orchard applicators.

A meta-analytic review of the effectiveness of single-layer clothing in preventing exposure from pesticide handling

This review summarizes available information on the penetration of pesticides through single-layer clothing by pesticide handlers and introduces epidemiological and observational studies on pesticide exposure. The data for this report were taken from peer-reviewed articles, publicly available government reports, and publicly available government reviews of registrant-submitted data and information. The arithmetic mean of calculated clothing penetration was obtained for various parts of the body (upper arm, lower arm, chest/torso, back/torso, upper leg, and lower leg) that were exposed to pesticide. The range of pesticide penetration to the various parts of the body through single-layer clothing during mixing, loading, and application (MLA) activities was found to be 6.2% ± 5.7% to 21.4% ± 6.7%, which demonstrates a potential for increased and unintentional pesticide exposures. Based on this evaluation, some accepted default values for protection against pesticide exposure may be overestimated.

Dermal & inhalation exposure of operators during fungicide application in vineyards. Evaluation of coverall performance

In the present study the dermal and the inhalation exposure of five operators during fungicide applications in vineyards were determined. The produced exposure datasets can be used as surrogate for the estimation of the actual and the potential dermal as well as inhalation operator exposure levels for this application scenario. The dermal exposure was measured using the whole body dosimetry method while the inhalation exposure with the use of personal air sampling devices with XAD tubes located on the operator's breathing zone. Ten field trials were carried out by 5 different operators using a tractor assisted hand-held lance with spray gun at the Tanagra region of Viotia, Greece. An in-house GC-ECD analytical method was developed and validated for the determination of penconazole, which was the active substance (a.s.) of the fungicide formulation used in field trials. The mean recovery of field-fortified samples was 81%. The operator exposure results showed expected variability and were compared to those derived from the German model for prediction of operator exposure. The comparison of the 75th percentile values for an operator wearing personal protection equipment has shown that the measured levels were 2.2 times lower than those estimated by the German model. The levels of actual dermal exposure ranged from 2 to 19 mg/kg a.s. applied. The protection provided by the two types of coveralls was evaluated and in comparison to the existing reduction factors used for other types of PPE (coveralls) was found satisfactory for the operator under the conditions of the specific applications.

Chlorine and hydrogen cyanide gas interactions with human skin: in vitro studies to inform skin permeation and decontamination in HAZMAT incidents

Accidental or intentional toxic gas releases may result in significant public health and psychological consequences. Management of exposed individuals during HAZMAT incidents should be risk-based and supported by a suitable scientific evidence base. There appear to be large evidence gaps in relation to dermal absorption of gases, as well as management advice for potentially exposed individuals. Chlorine and hydrogen cyanide are two common HAZMAT gases and this paper addresses the need for experimental data tailored to HAZMAT scenarios and first responders. In addition to time variations of gas concentration, the modifying effects of clothing, temperature, and oil-based sunscreen on epidermal absorption and penetration are assessed. Results for chlorine show little penetration up to 500 ppm but with small enhancing effects due to heavy cotton and oil-based sunscreen. Hydrogen cyanide up to 800 ppm shows minor penetration consistent with previous studies, with little variability in the presence of sunscreen and clothing. Practical guidelines to support the decision-making of emergency responders with regard to personal decontamination have been derived.

Dermal exposure associated with occupational end use of pesticides and the role of protective measures

BACKGROUND

Occupational end users of pesticides may experience bodily absorption of the pesticide products they use, risking possible health effects. The purpose of this paper is to provide a guide for researchers, practitioners, and policy makers working in the field of agricultural health or other areas where occupational end use of pesticides and exposure issues are of interest.

METHODS

This paper characterizes the health effects of pesticide exposure, jobs associated with pesticide use, pesticide-related tasks, absorption of pesticides through the skin, and the use of personal protective equipment (PPE) for reducing exposure.

CONCLUSIONS

Although international and national efforts to reduce pesticide exposure through regulatory means should continue, it is difficult in the agricultural sector to implement engineering or system controls. It is clear that use of PPE does reduce dermal pesticide exposure but compliance among the majority of occupationally exposed pesticide end users appears to be poor. More research is needed on higher-order controls to reduce pesticide exposure and to understand the reasons for poor compliance with PPE and identify effective training methods.

Procedures to evaluate the efficiency of protective clothing worn by operators applying pesticide

The evaluation of the efficiency of whole-body protective clothing against pesticides has already been carried out through field tests and procedures defined by international standards, but there is a need to determine the useful life of these garments to ensure worker safety. The aim of this article is to compare the procedures for evaluating efficiency of two whole-body protective garments, both new and previously used by applicators of herbicides, using a laboratory test with a mannequin and in the field with the operator. The evaluation of the efficiency of protective clothing used both quantitative and qualitative methodologies, leading to a proposal for classification according to efficiency, and determination of the useful life of protective clothing for use against pesticides, based on a quantitative assessment. The procedures used were in accordance with the standards of the modified American Society for Testing and Materials (ASTM) F 1359:2007 and International Organization for Standardization 17491-4. The protocol used in the field was World Health Organization Vector Biology and Control (VBC)/82.1. Clothing tested was personal water repellent and pesticide protective. Two varieties of fabric were tested: Beige (100% cotton) and Camouflaged (31% polyester and 69% cotton). The efficiency in exposure control of the personal protective clothing was measured before use and after 5, 10, 20, and 30 uses and washes under field conditions. Personal protective clothing was worn by workers in the field during the application of the herbicide glyphosate on weed species in mature sugar cane plantations using a knapsack sprayer. The modified ASTM 1359:2007 procedure was chosen as the most appropriate due to its greater repeatability (lower coefficient of variation). This procedure provides quantitative evaluation needed to determine the efficiency and useful life of individual protective clothing, not just at specific points of failure, but according to dermal protection as a whole. The qualitative assessment, which is suitable for verification of garment design and stitching flaws, does not aid in determining useful life, but does complement the quantitative evaluation. The proposed classification is appropriate and accurate for determining the useful life of personal protective clothing against pesticide materials relative to number of uses and washes after each use. For example, the Beige garment had a useful life of 30 uses and washes, while the Camouflaged garment had a useful life of 5 uses and washes. The quantitative evaluation aids in determining the efficiency and useful life of individual protective clothing according to dermal protection as a whole, not just at specific points of failure.

Application of skin contamination studies of ammonia gas for management of hazardous material incidents

In an atmospheric HAZMAT release unprotected public dermal exposure is often of short duration, but with potential secondary exposure if not decontaminated promptly. Mass decontamination is resource intensive and needs to be justified. For many HAZMAT agents there is no evidence-base on which to provide guidance on decontamination, particularly for non-symptomatic worried well. It is important to understand the influence of street clothing and environmental and other factors. Ammonia is a common HAZMAT agent and was selected for in vitro human skin studies of absorption, penetration and off-gassing at test concentrations up to 2000 ppm, incorporating primary and secondary exposure combinations up to 60 min. Intact skin provided a good barrier to ammonia penetration. Heavy street clothing such as denim was found to act as an initial barrier to skin absorption but subsequently as a reservoir for secondary exposure, under variable temperature and humidity conditions. Rapid off-gassing was observed for lighter fabrics including polyester and cotton. The findings here have been summarized as a set of practical guidelines for emergency responders who are required to make decisions about ammonia decontamination including for non-symptomatic individuals. This evidence-based diagrammatic approach allows for specific actions based on different atmospheric ammonia concentrations and other parameters.

Exposure and health risk assessment of applicators to DDT during indoor residual spraying in malaria vector control program

We assessed exposure of applicators, health risk of DDT to the applicators and evaluated the applicability of existing pesticide exposure models for indoor residual spraying (IRS). Patch sampling for dermal and personal air sampler for inhalation exposure were used in monitoring 57 applicators on the exposure assessment to DDT. The exposure of the applicators was also estimated using three exposure models. The mean actual dermal exposure was 449 mg total DDT per applicator per one house treatment. The applicators were exposed to DDT much beyond the estimated AOEL (acceptable operator exposure level) of DDT. The exposure estimated with ConsExpo 5.0 b01 model is situated between the median and the 75th percentile of the experimental data. On the other hand, spraying model 1 and spraying model 10 overestimate the exposure. Thus, these three models cannot be directly used for the particular circumstances of IRS as a tool for risk assessment. In general, use of DDT in IRS as a control method for malaria mosquitoes holds a high health risk for the applicators. Strict implementation of spraying procedures stated in the IRS manual of World Health Organization (WHO) is necessary to reduce the exposure level and health risk of applicators to DDT.

Fate and distribution of fipronil on companion animals and in their indoor residences following spot-on flea treatments

Use of fipronil {5-amino-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-trifluoromethyl)sulfinyl]-1H-pyrazole-3-carbonitrile CAS 120068-37-3} topical pet products on dogs and cats introduces low level residues into residences. Distribution and fate studies of fipronil on pets and in residences were performed to evaluate potential determinants of human exposure. Fipronil, desulfinyl fipronil, fipronil sulfone and fipronil sulfide were measured on hair clippings and brushed hair. The derivatives usually represented <10% of fipronil applied. Cotton gloves worn over impervious nitrile gloves, cotton cloths placed indoors in locations frequented by pets, and cotton socks worn by residents as direct dosimeters collected fipronil and its derivatives listed above in low amounts during 4-week study periods. Subsequent acid hydrolysis urine biomonitoring did not reveal significant excretion of biomarkers at ppb levels. The human exposure potential of fipronil is low relative to levels of health concern.

Environmental and biological monitoring in the estimation of absorbed doses of pesticides

Exposure to pesticides affects most of the population, not only persons occupationally exposed. In a context of high variability of exposure, biological monitoring is important because of the various routes by which exposure can occur and because it assesses both occupational and non-occupational exposure. The main aim of this paper was to critically compare estimates of absorbed dose measured by environmental and biological monitoring in situations in which they could both be applied. The combination of exposure measurements and biological monitoring was found to provide extremely important information on the behaviour of employees, and on the proper use and effectiveness of personal protection equipment.

Concurrent 2,4-D and triclopyr biomonitoring of backpack applicators, mixer/loader and field supervisor in forestry

Two herbicides, 2,4-D and triclopyr esters (application ratio 1.6:1 acid equivalents) were applied as a tank mix by a crew of 8 backpack sprayer applicators, a mixer/loader, and a field supervisor. The crew was employed in a conifer release program in northern California during the summer of 2002. Biomonitoring (urine, 24 h) utilized 2,4-D and triclopyr (a.e.) as rapidly excreted exposure biomarkers. The absorbed dosages of 2,4-D and triclopyr were calculated based upon cotton whole body suits and biomonitoring. Dosages based upon accumulation of the herbicides on body suits averaged 42.6 μg (a.e.) 2,4-D/kg-d and 8.0 μg (a.e.) triclopyr/kg-d. Six consecutive days of concurrent urine collections showed that backpack applicators excreted an average of 11.0 μg (a.e.) 2,4-D/kg-d and 18.9 μg (a.e.) triclopyr/kg-d. Estimates based upon curve fitting were 17.1 and 29.3 μg (a.e.)/kg-d, respectively. Results suggest that passive dosimetry for 2,4-D consistently overestimated the dosage measured using biomonitoring by a factor of 2-3 fold, while for triclopyr, passive dosimetry underestimated the absorbed dose based on biomonitoring by a factor of 2-4 fold.

Determination of operator exposure levels to insecticide during bait applications in olive trees: study of coverall performance and duration of application

In this study the operator exposure levels during bait applications of an insecticide in olive groves were determined using a whole body dosimetry method for dermal exposure. The study design allowed the roles of application task duration and coverall type to be evaluated as factors influencing operator exposure. Twenty applications were carried out with knapsack sprayers in the Tanagra region of Viotia, Greece, ten of which were for a 1h and ten for a 3h duration. An in-house GC-NPD analytical method was developed and validated for the determination of malathion, the active substance (a.s.) of the insecticide formulation used in field trials. The mean recovery of field-fortified samples was 84% (%RSD=3.0). Field trial results generally indicated lower operator exposure levels than indicated by the most relevant operator exposure predictive model. Residues of malathion on internal dosimeters were compared to those measured on the respective outer coveralls (potential dermal exposure) to evaluate the protective factor of each one of the two coverall types used. Both coverall types provided satisfactory levels of protection and can be considered as suitable protection for the conditions of the application scenario studied. Furthermore, the results indicated that there is not a strong correlation between exposure levels and duration of application.

Percutaneous absorption and exposure assessment of pesticides

Dermal exposure to a diverse range of chemicals may result from various uses. In order to assess exposure and estimate potential risks, accurate quantitative data on absorption are required. Various factors will influence the final results and interpretations of studies designed to assess the ability of compounds to penetrate the skin. This overview will discuss skin penetration by pesticides, emphasizing key parameters to be considered from the perspective of exposure assessment.

Performance of different work clothing types for reducing skin exposure to pesticides during open field treatment

The aim of this study was to estimate the performance of different work clothing types for reducing skin exposure to five pesticides (azinphos-methyl, terbutylazine, alachlor, dimethoate, and dicamba) in field distribution by tractor equipped with boom sprayer. Performance was assessed by measuring the penetration factors of different types of work clothing. The results show that the protection offered by personal protective equipment (PPE) was always >97%, whereas the performance of cotton garments ranged from 84.1% to 92.5%. The different cotton garments differed significantly in their permeability, and the upper part of the body was the anatomical region showing the greatest values of the penetration factors. These results confirm the necessity of using PPE properly to minimise dermal exposure to pesticides.

Dermal exposure of pesticide applicators as a measure of coverall performance under field conditions

In this study, the field performance of two coverall designs used by pesticide applicators was determined. Two coverall types were selected based on data from previously conducted comfort testing under field conditions in southern Europe. Dermal exposure was measured during 22 applications conducted with 11 operators using similar hand-held spray guns in greenhouse pepper crops in the Ierapetra region of Crete, Greece. One of the coverall designs studied was made from a cotton/polyester material treated with a water-repellent Resist Spills(R) finish, which was compared in the field study to a coverall of similar design, but using a woven, untreated cotton material. An in-house analytical method was developed and validated for determining residues of the active substance (a.s.) malathion on the dosimeters. The derived levels of dermal exposure were used as a measure of the protection provided by the two types of coveralls. In addition, by comparing the total amount of the a.s. recovered from outer and inner dosimeters (potential dermal exposure = 238.8 mg kg(-1) a.s. for the cotton coverall and 160.44 mg kg(-1) a.s. for the Resist Spills coverall), a value could be determined for the degree of coverall penetration. The mean penetration (milligrams per kilogram a.s.) of the outer coveralls, calculated as a percentage of the total contamination, was 0.4% for the water-repellent coverall and 2.3% for the cotton coverall. The mean recovery from the laboratory and field-fortified samples was >91 and 74%, respectively and used as the main criterion for quality control of the analytical data. Under the field trial conditions evaluated, both the coverall designs gave better protection than the default values used in the most relevant predictive exposure model. Therefore, they could be considered as appropriate tools of personal protection when both comfort and field performance is taken into account under the specific application scenario.

A probabilistic risk assessment for deployed military personnel after the implementation of the "Leishmaniasis Control Program" at Tallil Air Base, Iraq

Leishmaniasis has been of concern to the U.S. military and has re-emerged in importance because of recent deployments to the Middle East. We conducted a retrospective probabilistic risk assessment for military personnel potentially exposed to insecticides during the "Leishmaniasis Control Plan" (LCP) undertaken in 2003 at Tallil Air Base, Iraq. We estimated acute and subchronic risks from resmethrin, malathion, piperonyl butoxide (PBO), and pyrethrins applied using a truck-mounted ultra-low-volume (ULV) sprayer and lambda-cyhalothrin, cyfluthrin, bifenthrin, chlorpyrifos, and cypermethrin used for residual sprays. We used the risk quotient (RQ) method for our risk assessment (estimated environmental exposure/toxic endpoint) and set the RQ level of concern (LOC) at 1.0. Acute RQs for truck-mounted ULV and residual sprays ranged from 0.00007 to 33.3 at the 95th percentile. Acute exposure to lambda-cyhalothrin, bifenthrin, and chlorpyrifos exceeded the RQ LOC. Subchronic RQs for truck-mounted ULV and residual sprays ranged from 0.00008 to 32.8 at the 95th percentile. Subchronic exposures to lambda-cyhalothrin and chlorpyrifos exceeded the LOC. However, estimated exposures to lambda-cyhalothrin, bifenthrin, and chlorpyrifos did not exceed their respective no observed adverse effect levels.

Assessing exposure to allied ground troops in the Vietnam War: a comparison of AgDRIFT and Exposure Opportunity Index models

The AgDRIFT aerial dispersion model is well validated and closely related to the AGDISP model developed by the USDA Forest Service to determine on- and off-target deposition and penetration of aerially applied pesticide through foliage of trees. The Exposure Opportunity Index (EOI) model was developed to estimate relative exposure of ground troops in Vietnam to aerially applied herbicides. We compared the output of the two models to determine whether their predictions were in substantial agreement, but found a total lack of concordance. While the AgDRIFT model estimated that ground-level deposition through foliage was reduced more than 20 orders of magnitude at less than 1 km from the flight line, the EOI model predicted deposition declines less than one order of magnitude 4 km from the flight line. Interestingly the EOI model predicts a four-fold variability in EOI on the flight line, where exposure should be essentially invariant because the spray apparatus is designed to apply herbicide at a constant rate. We believe that the EOI model cannot be used to provide individual exposure estimates for the purpose of conducting epidemiologic studies. Moreover, evaluation of the position data for both herbicide spray swaths and troop locations, together with the actual patterns of spray deposition predicted by the AgDRIFT model, suggests that precise individual-level exposure assessments for ground troops in Vietnam are impossible. However, we suggest that well-validated tools like AgDRIFT can be used to estimate exposure to groups of individuals.

Comparative evaluation of absorbed dose estimates derived from passive dosimetry measurements to those derived from biological monitoring: validation of exposure monitoring methodologies

Passive dosimetry (PD) methods for measuring and estimating exposure to agricultural workers (i.e., persons handling agricultural chemicals and working in treated crops) have been in use since the 1950s. A large number of studies were conducted in the 1950s through 1970s to characterize exposure. Since the 1980s quantitative dermal PD methods are used in conjunction with inhalation PD methods to measure whole-body exposure. These exposure or absorbed dose estimates are then compared to "no effect" exposure levels for hazards identified in toxicology studies, and have become the standard for risk assessment for regulatory agencies. The PD methods used have never been validated. Validation in the context of human exposure monitoring methods means that a method has been shown to measure accurately a delivered dose in humans. The most practical alternative to isolating parts of the body for validating recovery methods is to utilize field exposure studies in which concurrent or consecutive measurements of exposure and absorbed dose have been made with PD and biomonitoring in the same cohorts of individuals. This ensures that a direct comparison can be made between the two estimates of absorbed dose, one derived from PD and the other from biomonitoring. There are several studies available (published and proprietary) employing both of these approaches. Reports involving 14 concurrent or consecutive PD-biomonitoring studies were quantitatively evaluated with 18 different methods of application or reentry scenarios for eight different active ingredients for which measured human kinetics and dermal absorption data existed. This evaluation demonstrated that the total absorbed dose estimated using PD for important handler and reentry scenarios is generally similar to the measurements for those same scenarios made using human urinary biomonitoring methods. The statistical analysis of individual worker PD:biomonitoring ratios showed them to be significantly correlated in these studies. The PD techniques currently employed yield a reproducible, standard methodology that is valid and reliably quantifies exposure.