Exploring Associations Between Postural Balance and Levels of Urinary Organophosphorus Pesticide Metabolites

OBJECTIVE

Apply a data-driven approach to explore associations between postural balance and pesticide exposure among Latino farmworkers and non-farmworkers.

METHODS

Lasso-regularized, generalized linear models were used to examine associations between postural control measures in four experimental conditions (2 visual × 2 cognitive difficulty) and dialkylphosphate (DAP) urinary metabolite levels.

RESULTS

Obtained models generally performed poorly at explaining postural control measures. However, when both visual and cognitive conditions were altered-the most challenging balance condition-models for some postural balance measures contained several DAP metabolites and had relatively better fits.

CONCLUSIONS

The current results were equivocal regarding associations between postural control measures and DAP metabolite concentrations. However, farmworker status appears to be an important variable in understanding this association. Future work should use a posturally- and cognitively-challenging test condition to reveal any potential associations.

Organophosphate pesticide exposure and dialkyl phosphate urinary metabolites among chili farmers in northeastern Thailand

BACKGROUND

Chlorpyrifos and profenofos are organophosphate pesticides (OPPs), we studied exposure and urinary metabolites in an agricultural area in the northeastern of Thailand during the chili-growing season (March - April) in 2012.

OBJECTIVE

This study was designed to assess pesticide exposure concentration through dermal and inhalation pathways and to find and depict a relationship between urinary metabolites and means of exposure.

MATERIALS AND METHODS

To estimate the pesticides exposure concentration, dermal wipes (hand, face, and feet), dermal patches and air samples were collected from 38 chili farmers. The morning void of pre and post application urine samples was an indicator of biological monitoring in the study which derived from 39 chili farmers.

RESULTS

Chlorpyrifos and profenofos residues were detected on dermal patches, face wipes, and hand wipe samples, while no significant residues were found on the feet. Using a personal air sampling technique, all air samples detected pesticide residues. However, significant correlation between dermal pesticide exposure concentration and inhalation was not found (p>0.05). For urinary metabolite levels, there was a relationship between the first pre application morning void and post application morning void (p < 0.05); similar to the association between the first pre application morning void and the second post application morning void (p < 0.05). The main relationship between pesticide exposure and urinary metabolite was found to have been relevant to dermal exposure (r= 0.405; p < 0.05).

CONCLUSIONS

The results of this study could suggested that public health education training programs, including the use of appropriate personal protective equipment (PPE), should be offered for the chili growing farmers in order to improve their ability to properly use pesticides.

KEY WORDS

pesticide exposure, chili farmers, urinary metabolites, organophosphate pesticides.

Improved analysis of dialkylphosphates in urine using strong anion exchange disk extraction and in-vial derivatization

Determination of dialkylphosphates (DAPs) in urine is useful for assessing human exposure to organophosphates (OPs). An improved method for the determination of four DAPs based on a strong anion exchange (SAX) disk extraction and in-vial derivatization was presented in this study. The matrix effect of urine components such as chloride ion and phosphate ion by using a SAX disk to extract DAPs in urine analysis was carefully evaluated. It was observed that the chloride ion mainly affected the extraction of diethylphosphate (DEP), dimethylthiophosphate (DMTP), and diethylthiophosphate (DETP) in urine. The addition of silver hydroxide could significantly improve the extraction efficiencies of these three DAPs, but it decreases the extraction efficiencies of dimethyldithiophosphate (DMDTP) and diethyldithiophosphate (DEDTP). The LOD of this method for DMTP, DETP, DMDTP, and DEDTP are 5, 5, 11, and 5 microg/L, respectively. A pretreatment strategy for the determination of DMTP, DMDTP, DETP, and DEDTP in urine was proposed which can provide reliable and prompt determination of routine urine analysis.

Biologic monitoring to characterize organophosphorus pesticide exposure among children and workers: an analysis of recent studies in Washington State

We examined findings from five organophosphorus pesticide biomonitoring studies conducted in Washington State between 1994 and 1999. We compared urinary dimethylthiophosphate (DMTP) concentrations for all study groups and composite dimethyl alkylphosphate (DMAP) concentrations for selected groups. Children of pesticide applicators had substantially higher metabolite levels than did Seattle children and farmworker children (median DMTP, 25 microg/L; p < 0.0001). Metabolite levels of children living in agricultural communities were elevated during periods of crop spraying. Median DMTP concentrations for Seattle children and farmworker children did not differ significantly (6.1 and 5.8 microg/L DMTP, respectively; p = 0.73); however, the DMAP concentrations were higher for Seattle children than for farmworker children (117 and 87 nmol/L DMAP, respectively; p = 0.007). DMTP concentrations of U.S. children 6-11 years of age (1999-2000 National Health and Nutrition Examination Survey population) were higher than those of Seattle children and farmworker children at the 75th, 90th, and 95th percentiles. DMTP concentrations for workers actively engaged in apple thinning were 50 times higher than DMTP concentrations for farmworkers sampled outside of peak exposure periods. We conclude that workers who have direct contact with pesticides should continue to be the focus of public health interventions and that elevated child exposures in agricultural communities may occur during active crop-spraying periods and from living with a pesticide applicator. Timing of sample collection is critical for the proper interpretation of pesticide biomarkers excreted relatively soon after exposure. We surmise that differences in dietary exposure can explain the similar exposures observed among farmworker children, children living in the Seattle metropolitan area, and children sampled nationally.

Evaluation of skin and respiratory doses and urinary excretion of alkylphosphates in workers exposed to dimethoate during treatment of olive trees

This article describes a study of exposure to dimethoate during spraying of olive trees in Viterbo province in central Italy. Airborne concentrations of dimethoate were in the range 1.5 to 56.7 nmol/m(3). Total skin contamination was in the range 228.4 to 3200.7 nmol/d and averaged 96.0% +/- 3.6% of the total potential dose. Cotton garments afforded less skin protection than waterproof ones, which were in turn associated with higher skin contamination than disposable Tyvek overalls. Total potential doses and estimated absorbed doses, including their maxima, were below the acceptable daily intake of dimethoate, which is 43.6 nmol/kg body weight (b.w.). Urinary excretion of alkylphosphates was significantly higher than in the general population, increasing with exposure and usually showing a peak in the urine sample collected after treatment. Metabolite concentrations were influenced by the type of individual protection used: minimum levels were associated with the closed cabin and maximum levels with absence of any respiratory or hand protection. Urinary alkylphosphates showed a good correlation with estimated absorbed doses and are confirmed as sensitive biologic indicators of exposure to phosphoric esters.

Organophosphorous pesticide exposure alters sperm chromatin structure in Mexican agricultural workers

Our objective was to evaluate alterations in sperm chromatin structure in men occupationally exposed to a mixture of organophosphorus pesticides (OP) because these alterations have been proposed to compromise male fertility and offspring development. Chromatin susceptibility to in situ acid-induced denaturation structure was assessed by the sperm chromatin structure assay (SCSA). Urinary levels of alkylphosphates (DAP) were used to assess exposure. Diethylthiophosphate (DETP) was the most frequent OP metabolite found in urine samples indicating that compounds derived from thiophosphoric acid were mainly used. Chromatin structure was altered in most samples. About 75% of semen samples were classified as having poor fertility potential (>30% of Percentage of DNA Fragmentation Index [DFI%]), whereas individuals without OP occupational exposure showed average DFI% values of 9.9%. Most parameters of conventional semen analysis were within normality except for the presence of immature cells (IGC) in which 82% of the samples were above reference values. There were significant direct associations between urinary DETP concentrations and mean DFI and SD-DFI but marginally (P = 0.079) with DFI%, after adjustment for potential confounders, including IGC. This suggests that OP exposure alters sperm chromatin condensation, which could be reflected in an increased number of cells with greater susceptibility to DNA denaturation. This study showed that human sperm chromatin is a sensitive target to OP exposure and may contribute to adverse reproductive outcomes. Further studies on the relevance of protein phosphorylation as a possible mechanism by which OP alter sperm chromatin are required.

Exposure to the organophosphate diazinon: data from a human volunteer study with oral and dermal doses

Biological monitoring of occupational exposure to diazinon is possible by the determination of blood cholinesterase activity and by the measurement of metabolites in urine. However, there is little data to aid in the interpretation of results. This study gave oral (11 microg kg(-1) (36 nmol kg(-1)) body weight) and occluded dermal (100 mg (329 micromol)) doses of diazinon to five volunteers and analysed blood and urine samples for plasma and erythrocyte cholinesterase and urinary dialkyl phosphate (DAP) metabolites of diazinon: diethyl phosphate (DEP) and diethyl thiophosphate (DETP). Following oral and dermal exposure, peak urinary DAP levels occurred at 2 and 12 h, respectively. The apparent urinary elimination half-lives of DAP metabolites following oral and dermal exposure were approximately 2 and 9 h, respectively. Approximately 60% of the oral dose and 1% of the dermal dose was excreted as urinary DAP metabolites, with 90% of the dermal dose being recovered from the skin surface. On a group basis, there was no statistically significant mean depression in plasma or erythrocyte cholinesterase when compared with pre-exposure levels for either dosing experiment. The observed elimination kinetics of diazinon metabolites suggest a biological monitoring strategy for occupational exposure to diazinon based on urine samples collected at the end of shift.

Method for the determination of dialkyl phosphates in urine by strong anion exchange disk extraction and in-vial derivatization

A method for the determination of four dialkylphosphate metabolites in urine by strong anion exchange disk (SAX) was investigated. Calcium hydroxide was added to a 1-mL urine sample to reduce interference. The aliquot was passed through the SAX disk to accumulate dialkylphosphate metabolites on the disk. The retained dialkylphosphate metabolites were derivatized with methyl iodide in acetonitrile online, and the resulting methyl esters of dialkylphosphate metabolites were directly analyzed by capillary column gas chromatography with flame photometric detection. The recoveries of these dialkylphosphate metabolites were found to be stable. When the intact sample was diluted with deionized water at a 1:1 ratio, the recoveries were both increased and stabilized. The urine samples collected from eight fruit farmers showed that levels of dialkylphosphate metabolites in urine were significantly different before and after pesticide application, indicating the method established in this study is applicable for real sample analysis. Compared with previous studies, this method not only can greatly simplify sample preparation, but it can also significantly reduce the consumption of toxic solvents in sample preparation.

Prothiofos metabolites in human poisoning

CASE REPORT

A 63-year-old woman was admitted to a local hospital after the ingestion of 40% prothiofos preparation (Tokuthion) 370 mL. Gastric lavage was performed and cathartics, active charcoal, diuretics, atropine sulfate, and pralidoxime were administered. Serum cholinesterase activity was 1.3 IU/L (normal 200-460 IU/L). The patient's consciousness was gradually restored after 4 hours of charcoal hemoperfusion and she was discharged 5 days after admission with no sequelae.

METHOD

Plasma and urine prothiofos and metabolites were detected by gas chromatography-flame photometry and gas chromatography-mass spectrometry. Two despropyl metabolites were synthesized for identification and estimation.

RESULTS

The main metabolites were identified with authentic prothiofos and methyl esters of synthesized des-S-propyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phosphate), despropyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phospholothiolate), and des-S-propyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorothioate). Despropyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorodithioate) was also identified in plasma. Large amounts of the hydrolyzed product, 2,4-dichlorophenol and its conjugate were also found. The metabolic pattern of prothiofos in humans appears to be different from that in rats.

Dimethylphosphorus metabolites in serum and urine of persons poisoned by malathion or thiometon

The urinary excretion rates of dimethyl-phosphate, -phosphorothioate and -phosphorodithioate were studied in six persons of whom four had ingested a concentrated solution of malathion and two of thiometon. The concentration decrease of single and total dimethylphosphorus metabolites was biphased, with a fast initial rate and a slow later rate. The excretion rate of total metabolites in the faster phase depended on the initial concentration in urine. At concentrations higher than 100 nmol/mg creatinine, the excretion half-times ranged from 7.5 to 15.4 h and at concentrations between 52 and 95 nmol/mg creatinine from 34.7 to 55.4 h. Non-metabolized malathion was detected only in one urine sample collected from one person immediately after hospitalization. Two persons poisoned with malathion were taken blood serum samples for the analysis of the parent pesticide and its metabolites on a daily basis after hospitalization. The parent pesticide was detectable in the serum only one day after the poisoning. The concentration of total malathion dimethylphosphorus metabolites in serum decreased very quickly within 1.5 days after hospitalization. The total metabolite elimination half-times were 4.1 and 4.7 h in the initial phase, and 53.3 and 69.3 days in the later slower elimination phase. There was no correlation between maximum concentrations of total metabolites measured in serum and/or urine on the day of admission to hospital and the initial depression of serum cholinesterase (BChE, EC 3.1.1.8) and erythrocyte acetylcholinesterase (AChE, EC 3.1.1.7).

Quantitation of postmortem profenofos levels

CASE REPORT

An 88-year-old woman was found dead, and suicidal ingestion of profenofos, an organophosphate pesticide, was suspected.

METHOD

Gas chromatography-nitrogen phosphorus detection was employed for quantitation of profenofos after its identification by gas chromatography/mass spectrometry.

RESULTS

The levels of profenofos in whole blood, urine, and gastric contents were 1200 ng, 350 ng, and 3.35 mg/mL, respectively.

Biological monitoring of organophosphorus pesticide exposure among children of agricultural workers in central Washington State

Children up to 6 years of age who lived with pesticide applicators were monitored for increased risk of pesticide exposure: 48 pesticide applicator and 14 reference families were recruited from an agricultural region of Washington State in June 1995. A total of 160 spot urine samples were collected from 88 children, including repeated measures 3-7 days apart. Samples were assayed by gas chromatography flame photometric detector for dimethylphosphate metabolites. Dimethylthiophosphate (DMTP) was the dominant metabolite. DMTP levels were significantly higher in applicator children than in reference children (p = 0.015), with median concentrations of 0.021 and 0.005 microg/ml, respectively; maximum concentrations were 0.44 and 0.10 microg/ml, respectively. Percentages of detectable samples were 47% for applicator children and 27% for reference children. A marginally significant trend of increasing concentration was observed with decreasing age among applicator children (p = 0.060), and younger children within these families had significantly higher concentrations when compared to their older siblings (p = 0.040). Applicator children living less than 200 feet from an orchard were associated with higher frequency of detectable DMTP levels than nonproximal applicator children (p =0.036). These results indicate that applicator children experienced higher organophosphorus pesticide exposures than did reference children in the same community and that proximity to spraying is an important contributor to such exposures. Trends related to age suggest that child activity is an important variable for exposure. It is unlikely that any of the observed exposures posed a hazard of acute intoxication. This study points to the need for a more detailed understanding of pesticide exposure pathways for children of agricultural workers.

Biological monitoring of organophosphorus pesticide exposure among children of agricultural workers in central Washington State

Children up to 6 years of age who lived with pesticide applicators were monitored for increased risk of pesticide exposure: 48 pesticide applicator and 14 reference families were recruited from an agricultural region of Washington State in June 1995. A total of 160 spot urine samples were collected from 88 children, including repeated measures 3-7 days apart. Samples were assayed by gas chromatography flame photometric detector for dimethylphosphate metabolites. Dimethylthiophosphate (DMTP) was the dominant metabolite. DMTP levels were significantly higher in applicator children than in reference children (p = 0.015), with median concentrations of 0.021 and 0.005 microg/ml, respectively; maximum concentrations were 0.44 and 0.10 microg/ml, respectively. Percentages of detectable samples were 47% for applicator children and 27% for reference children. A marginally significant trend of increasing concentration was observed with decreasing age among applicator children (p = 0.060), and younger children within these families had significantly higher concentrations when compared to their older siblings (p = 0.040). Applicator children living less than 200 feet from an orchard were associated with higher frequency of detectable DMTP levels than nonproximal applicator children (p =0.036). These results indicate that applicator children experienced higher organophosphorus pesticide exposures than did reference children in the same community and that proximity to spraying is an important contributor to such exposures. Trends related to age suggest that child activity is an important variable for exposure. It is unlikely that any of the observed exposures posed a hazard of acute intoxication. This study points to the need for a more detailed understanding of pesticide exposure pathways for children of agricultural workers.

Urinary excretion of alkylphosphates in the general population (Italy)

Xenobiotic residues and their metabolites in biological fluids of the general population are an important indicator of exposure to toxic substances dispersed in the environment. Urine samples collected from 124 subjects living in SW Tuscany, Italy were analyzed for alkylphosphates (dimethylphosphate, dimethylthiophosphate, dimethyldithiophosphate, diethylphosphate, diethylthiophosphate, diethyldithiophosphate), aspecific metabolites of organophosphorus insecticides. The compound most frequently found was dimethylthiophosphate which was detectable in 99% of the subjects analyzed, with a geometric mean of 70.7 nmol/g creatinine. The other substances were found in the following percentages of our population, at the following mean concentrations: dimethylphosphate, 87%, 62.8 nmol/g creat.; dimethyldithiophosphate, 48%, 21.1 nmol/g creat.; diethylphosphate, 81%, 27.4 nmol/g creat.; diethylthiophosphate, 73%, 22.8 nmol/g creat.; diethyldithiophosphate, 7%, 13.7 nmol/g creatinine. Subjects eating food (fruit, meat, vegetables) that was not their own produce showed higher urinary concentrations of nearly all the compounds. The other variables considered (sex, age, residence, alcohol, smoking, sampling period) seem to affect the percentages of positive values of the various substances but to different degrees. Age and source of foods were the most important variables for dimethylthiophosphate excretion when mean values were analyzed by Student's t-test and analysis of variance (ANOVA).

Biological monitoring of exposure to organophosphorus insecticides by assay of urinary alkylphosphates: influence of protective measures during manual operations with treated plants

Biological monitoring was carried out by assaying urinary dimethylated alkylphosphates [dimethyldithiophosphate (DMDTP), dimethylthio-phosphate (DMTP), and dimethylphosphate (DMP)] in 11 workers exposed to chlorpyrifos-methyl and azinphosmethyl during operations in a previously sprayed peach orchard. The subjects were divided into groups on the basis of the protective clothing worn. The results were compared with those of a reference group of 99 subjects not occupationally exposed to organophosphorus insecticides. The hand-wash liquid of the workers was also analyzed to evaluate skin contamination. Significantly higher levels of urinary excretion of alkylphosphates were found in all groups than in unexposed controls (Student's t test). A good correlation was found between quantities of the active ingredients on the hands and urinary excretion of total dimethylated alkylphosphates (r = 0.788) and of DMTP (r = 0.749) and DMP (r = 0.790) alone. The correlation between azinphos-methyl on the hands and urinary excretion of DMDTP was poor (r = 0.069). Under the working conditions investigated, the main route of absorption seems to be via the skin. Respiratory absorption, however, also appears significant in view of the difference in urinary excretion of dimethylated alkylphosphates found between subjects with and without face masks.

Metabolic fate of S,S,S-tributyl phosphorotrithioate (DEF) in the lactating goat

1. Metabolism of [1-14C] DEF (S,S,S-1-14C-tributyl phosphorotrithioate, 1) in the lactating goat has been investigated. A goat was dosed orally by capsule on 3 consecutive days at a rate of 0.82 mg/kg body weight/day based on 25 times the maximum DEF residue anticipated in animal feed. 2. Urine and milk were collected throughout the study. The goat was killed 21 h following the last treatment, and kidney, liver and composite samples of muscle and fat were collected. The radioactive residue levels (following the three doses) were 3.45 ppm in liver, 0.35 ppm in kidney, 0.19 ppm in fat, 0.06 ppm in muscle and 0.12 ppm in milk collected at the final 16 h and prior to killing. 3. Urinary metabolic profile indicated that DEF was efficiently metabolized to many metabolites. Tissue and milk extracts also indicated that DEF was extensively metabolized. 4. DEF comprised 31 and 5% of the total radioactive residue in fat and milk, respectively. The amount of DEF in liver, kidney and muscle represented < 1% of the total radioactive residue. 5. A major metabolite, 3-hydroxybutylmethyl sulphone (HBM sulphone, UP3), was found in tissue, milk and urine. The identification of this metabolite was accomplished by a combination of MS, nmr and comparison with an authentic standard. The glucuronide (UP1) and sulphate (UP2) conjugates of HBM sulphone were found in urine, and the sulphate conjugate was a major metabolite in kidney. 6. The hydrolytic products of DEF, S,S-dibutyl phosphorodithioate (Dibufos, U16) and S-butyl phosphorothiate (Bufos, U8), were identified as minor components in urine, comprising 5 and 4% of the total radioactive residue, respectively. Butyl mercaptan was not found, but mixed disulphides of butyl mercaptan with either glutathione (U10, 3%) or N-acetyl cysteine (U13, 2%) were found. 7. Direct evidence for the incorporation of DEF residue into natural constituents was also established. Fatty acids from milk and fat were isolated and shown to be radioactive.

Diethylphosphorus metabolites in serum and urine of persons poisoned by phosalone

The presence and elimination rate of phosalone and its diethylphosphorus metabolites in blood serum and urine were studied in persons who had ingested a concentrated phosalone solution. Phosalone was detected only in serum samples. As it was rapidly hydrolysed and eliminated from the body, its diethylphosphorus metabolites were a more sensitive indicator of exposure. The concentration decrease of phosalone in serum and of total diethylphosphorus metabolites in serum and urine followed the kinetics of a biphasic reaction. The faster elimination half-times in serum, calculated for two persons, were 2.3 and 3.4 h for phosalone and 3.4 and 38.6 h for total diethylphosphorus metabolites. In the faster phase the average elimination half-time of total urinary metabolites in five persons was 25 +/- 17 h. The kinetic data for total urinary metabolites in a person occupationally exposed to phosalone indicated an early and very fast elimination phase (elimination half-time 1.3 h), which was overlooked in poisoned persons. The proportions of single metabolites in total urinary metabolites in poisoned persons depended on whether the total amount of diethylphosphorus metabolites was above 1000 or below 1000 nmol/mg creatinine. Diethylphosphorodithioate predominated at high and diethylphosphate at low concentrations of total metabolites. The correlation between the maximum concentrations of total metabolites, measured in urine of poisoned persons on the day of admission to hospital or a day later, and the initial depression of serum cholinesterase (EC 3.1.1.8) and erythrocyte acetylcholinesterase (EC 3.1.1.7) activities was poor (r = 0.6).

Chlorpyrifos metabolites in serum and urine of poisoned persons

Concentrations of parent pesticide and corresponding diethylphosphorus metabolites in blood serum and urine were investigated in persons who had ingested a concentrated solution of organophosphorus pesticide chlorpyrifos. The organophosphate poisoning was indicated by a significant depression of blood cholinesterase (EC 3.1.1.7 and EC 3.1.1.8) activities. Blood and spot urine samples were collected daily after admission of the persons to hospital. Chlorpyrifos was detected only in serum samples in a period up to 15 days after poisoning. In the same samples chlorpyrifos oxygen analogue, chlorpyrifos oxon, was not detected. The presence of diethylphosphorothioate in all serum and urine samples confirmed that part of chlorpyrifos was hydrolysed before its oxidation. The maximum concentrations of chlorpyrifos in serum and of metabolites in serum and urine were measured on the day of admission. The decrease in concentrations followed the first-order kinetics with the initial rate constant faster and the later one slower. In the faster elimination phase chlorpyrifos was eliminated from serum twice as fast (t1/2 = 1.1-3.3 h) as the total diethylphosphorus metabolites (t1/2 = 2.2-5.5 h). The total urinary diethylphosphorus metabolites in six chlorpyrifos poisoned persons were excreted with an average elimination half-time of 6.10 +/- 2.25 h (mean +/- S.D.) in the faster and of 80.35 +/- 25.8 h in the slower elimination phase.

Correlation of fluorescent tracer measurements of dermal exposure and urinary metabolite excretion during occupational exposure to malathion

Nineteen workers conducting mixing and high-volume airblast applications of the organophosphorus pesticide malathion were monitored simultaneously by biological monitoring and fluorescent tracer evaluation of dermal exposure. Complete 72-hr urine samples were collected and analyzed for dimethylthiophosphate and dimethyldithiophosphate metabolites. Dermal exposure was measured through the addition of a fluorescent tracer to the tank mix, subsequent examination of the skin surface under long-wave ultraviolet light, and fluorescence quantification with a video imaging system. Dermal exposure to applicators was correlated highly with total metabolite excretion (r = 0.91). Mixer exposure was not correlated significantly (r = 0.73) because of wide scatter in the data and the small number of workers monitored. Applicator exposures were more than 3 times higher than mixer exposures, reflecting the high exposure potential inherent in airblast spraying. Exposure to regions protected by gloves or clothing was more than 75% of total exposure for both mixers and applicators. These results provide evidence that the fluorescent tracer technique is a valid methodology for measuring relative levels of dermal exposure during agricultural work activities. The technique also holds promise as a quantitative procedure for evaluating the effectiveness of engineering control strategies and protective clothing performance.

A behavioral evaluation of pest control workers with short-term, low-level exposure to the organophosphate diazinon

Neurobehavioral effects of short-term, low-level exposure to diazinon were investigated among 99 pest control workers tested before and after their work shift with a computer-assisted neurobehavioral test battery. Each subject completed a brief neurological screening examination, a symptom questionnaire, and tests of concentration, eye-hand coordination, pattern recognition, visual memory, and finger tapping. The diazinon metabolite diethylthiophosphate (DETP) was measured in pre- and post-shift urine samples collected from 46 diazinon applicators applying granulated diazinon onto residential properties with lawn spreaders, and 56 non-applicators. Post-shift median DETP for applicators and non-applicators was 24 and 3 ppb, respectively. Full shift, whole body exposure to diazinon was quantitated for 19 subjects using personal air monitoring and passive badges. Median diazinon exposure for applicators and non-applicators was 2.1 and 0.03 mg, respectively. Mean duration of pesticide application was 39 days (SD = 12 days) before testing. No adverse DETP-related changes in pre- or post-shift neurobehavioral function were found with multiple linear regression models after adjusting for age, sex, education, and ethanol intake, although Symbol-Digit pairing speed was slower among the applicators as a group. The prevalence of 18 symptoms possibly related to diazinon exposure was not elevated among applicators. The study failed to demonstrate diverse behavioral effects of short-term, low-level diazinon exposure in a pest control program which emphasized personal protective equipment and direct supervision.

The use of biological monitoring in the estimation of exposure during the application of pesticides

In order to assess the occupational health risk to workers using pesticides, accurate data on exposure (including knowledge of the primary route of exposure) and on absorption are needed. In addition, a well-defined no-effect level (NOEL) derived from suitable animal data must be available. Biological monitoring, urinary metabolite excretion in particular, frequently is used to indicate whether a worker has been exposed. Interpretation of the toxicological significance of the observed urinary metabolite levels is often difficult because the relationship between these levels and toxic dose are generally unknown. Another complication is the apparent lack of correlation between patch data and urinary metabolite data. The usefulness of a metabolite to predict exposure depends on many things, including detailed knowledge of absorption and excretion characteristics of the parent compound and identification of the metabolites. These data, when combined with appropriate toxicology data, permit an analysis of the potential health risks associated with an occupational exposure to toxic chemicals. This paper will correlate data from a number of studies in which the dermal penetration of azinphosmethyl (AM) was measured in rats, rabbits, monkeys and man; and urinary alkyl phosphate metabolites were measured in orchardists exposed to AM. The feasibility of utilizing metabolite excretion to estimate exposure and ultimate risk will be discussed.

[Renal excretion of dimethylphosphate and its thio-derivatives following application of dimethoate, bromophos, naled or trichlorfon to rats]

Dimethoate, bromophos, naled or trichlorophon were applied i.p. or p.o. to rats in 3 doses each differing by the factor 10. In the urine of 24 h gas chromatographic determination of dimethylphosphate (DM), O.O-dimethylthiophosphate (TP), and/or O.O-dimethyldithiophosphate (DT) were carried out. After i.p. application of dimethoate the excretion rate of DT calculated from the dates found with the lowest dosage differed significantly from those found with the two other doses (t-test; p = 0.01). The excretion rates of DM and TP, in the same way, or those of DM, TP, and DT after oral intake of dimethoate did not show any significant differences. The excretion rates of TP after bromophos and of DM after naled or trichlorophon did not differ significantly after the same way of application. The findings make evident that under the given test conditions the excretion rate of DM, TP, or DT is practically independent on the dose.

Diagnostic value of urinary dialkyl phosphate measurement in goats exposed to diazinon

Recognition of exposure to diazinon, an organophosphate insecticide, was studied in goats. Urine and milk dialkyl phosphate concentrations (DETP; O,O-diethyl phosphorothionate) and blood cholinesterase activity (ChE) and diazinon concentrations were measured. Groups (n = 3 each) given (orally) diazinon at doses of 0.5 mg/kg for 7 days (small dose) or 5 mg/kg for 7 days (large dose) were compared with goats acutely exposed to single doses of 150 mg/kg (n = 1) or 700 mg/kg (n = 1). Clinical signs of intoxication occurred only in the goat given the 700 mg/kg dose. Urinary DETP concentrations were sensitive indicators of diazinon exposure and provided quantitative differences between small, large, and acute dosage exposures. Milk DETP concentrations were not detected. Cholinesterase measurement was useful only in the acute exposure studies. Whole blood diazinon concentrations were detected only in goats given the large dose for 7 days and acutely exposed. Measurement of urinary DETP was a sensitive aid for recognition of diazinon exposure.

Comparison of measurement of dialkyl phosphates in milk/urine and blood cholinesterase and insecticide concentrations in goats exposed to the organophosphate insecticide, imidan

Recognition of exposure to imidan was assessed in goats by dialkyl phosphate concentrations, blood cholinesterase (ChE) determinations, and blood imidan concentrations. Groups of three goats received 5.0 mg imidan/kg/day (low dose) or 10 mg imidan/kg/day (high dose) for 7 days orally. One goat received no imidan and one goat received an acute single dose (200 mg/kg). The urine of all treated goats was examined for the excretory dialkyl phosphates, O,O-dimethyl phosphorodithioate (DMDTP) and O,O-dimethyl phosphorothionate (DMTP). The overall mean DMDTP urinary concentration was 19.1 ppm (10-mg/kg treatment group) and 7.2 ppm (5-mg/kg treatment group). These metabolites rapidly disappeared following removal of the treatment except in those goats clinically affected. Milk contained no identifiable concentrations of dialkyl phosphates. Cholinesterase depression was observed in all imidan-treated goats, and a dose effect was observed. No imidan was detected in whole blood of either the 5- or 10-mg/kg treatment groups. Low blood concentrations (ppb) of imidan were measured in the acute single-dose exposed goat. Both urinary DMDTP and blood ChE provided recognition of imidan exposure. DMDTP, however, was immediately present in urine after exposure and provided stronger support for organophosphate exposure than did blood ChE.