O,O-diethyl hydrogen phosphorodithioate

Exposure related observations in humans: other data

Administrative data

Endpoint:

exposure-related observations in humans: other data

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1993

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Publication on occuptional exposure to pesticides.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Biological Monitoring of Workers Occupationallly Exposed to Organophosphorus Pesticides

Author:

Nutley, B. P. & Cocker, J.

Year:

1993

Bibliographic source:

Pestic. Sci., 38, 315-322

Materials and methods

Type of study / information:

Development of biologocal monitoring method for assessing exposure to organophosphorus pesticides. The method is used to determine the concentration of six dialkyl phosphates and phosphorothioates in urine.

Endpoint addressed:

not applicable

Test guideline

Qualifier:

no guideline available

Deviations:

not applicable

Principles of method if other than guideline:

The method used for determination of the compounds in urine involved the azeotropic distillation of urine, derivatisation of the residue with pentafluorobenzylbromide followed by high resolution gas chromatography with flame photometric detection. The technique was applied to the analysis of over 400 urine samples obtained from 140 workers with potential occupational exposure to organophosphorous pesticides during agricultural activities. Wherever possible, blood samples were taken for measurement of red blood cell and plasma cholinesterase activity.

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

O,O-diethyl hydrogen phosphorodithioate

EC Number:

206-055-9

EC Name:

O,O-diethyl hydrogen phosphorodithioate

Cas Number:

298-06-6

Molecular formula:

C4H11O2PS2

IUPAC Name:

O,O-diethyl sulfanylphosphonothioate

Details on test material:

- Name of test material (as cited in study report): O,O-diethyl phosphorodithioate (DEPDT)

Method

Ethical approval:

not specified

Details on study design:

The method used for biological effect monitoring of workers occupationally exposed to organophosphorous pesticides is based on azeotropic distillation of metabolites with derivatisation using pentafluorobenzyl bromide and capillary gas chromatography with flame photometric detection.

Exposure assessment:

not specified

Details on exposure:

TYPE OF EXPOSURE:
Occupational exposure during various agricultural activities, sheep dipping or pesticide formulation.

TYPE OF EXPOSURE MEASUREMENT:
Biomonitoring (urine and blood)

Results and discussion

Results:

Workers using organophosphorus insecticide sprays or granules showed no detectable metabolites in the pre-exposure samples. In the post-exposure samples, the dialkyl phosphate and dialkyl phosphorothioate metabolites but not the dialkyl phosphorodithioates (DMPDT and DEPDT) were detected, which probably reflects the nature of the compound used. No significant decreases in either erythrocyte or plasma cholinesterase activity were seen in any post-exposure blood samples when compared with pre-exposure, baseline activity.
The general levels of metabolites seen in the urine of sheep dippers were similar to those found in other agricultural workers, and where concomitant cholinesterase measurements were made, none of the samples showed enzyme inhibition outside the normal range.
The formulation workers were regularly exposed to a variety of organophosphorus pesticides and no pre-exposure samples could be taken. Unlike the agricultural workers and sheep dippers, only 7% of urine samples from formulators had no detectable dialkyl phosphate or dialkyl phosphorothioate metabolite levels. Urine samples from these group of workers also showed detectable levels of dialkyl phosphorodithioate (DMPDT and DEPDT). The values obtained show a much greater range in concentrations than for any other occupational group and for several of the metabolites these urine samples showed the highest levels seen.
the only worker showing any depression of cholinesterase activity during the study was a formulation worker who showed a significant decrease in plasma cholinesterase activity but no depression of erythrocyte cholinesterase. This worker had raised urinary dialkyl phosphate levels and high levels of dialkyl phosphate metabolites. No increased levels of DEPDT were reported for this worker.

Any other information on results incl. tables

No other information.

Applicant's summary and conclusion

Conclusions:

Measurement of dialkyl phosphate metabolites in urine provides a sensitive biological monitoring method suitable for use in the assessment of occupational exposure to many organophosphorus pesticides. O,O-diethyl phosphorodithioate (DEPDT) was not detected in agricultural workers and formulation workers. Only in one sheep dipper, DEPDT was found at a concentration of 1 nmol/mmol creatine, post-exposure towards organophosphorus pesticides.

Executive summary:

A biological monitoring method was developed to assess occupational exposure to organophosphorus pesticides.

The method involves the azeotropic distillation of urine, derivatisation of the residue with pentafluorobenzylbromide followed by high resolution gas chromatography and was used to determine the concentration of six dialkyl phosphates and phosphorothioates in urine samples of 140 workers with potential occupational exposure to organophosphorus pesticides. In addition, blood samples were taken and examined for red blood cell and plasma cholinesterase activity.

The results show that in most cases where dialkyl phosphate metabolites were detected, this did not lead to depression of red cell or plasma cholinesterase activity. Formulation workers had higher urinary metabolite levels than any of the other groups studied and were the only group in which for one individual worker a significant reduction in cholinesterase activity was noted.

The results reveal that the method used is suitable for monitoring occupational exposure to organophosphorus pesticides.