Generic data base exposure

R.C. Honeycutt, The Usefulness of Farm Worker Exposure Estimates Based on Generic Data, in Dermal Exposure Related to Pesticide Use Discussion of Risk Assessment, ed. R.C. Honeycutt, G. Zweig, and N.N. Ragsdale, ACS Symposium Series 273, American Chemical Society, Washington, DC, pp. 369-375 (1985). 

This book provides an up-to-the-minute picture of the current status of research on measurement and risk assessment of dermal pesticide exposure for agricultural workers. The chapters also provide an insight into some newer areas (applications of mathematical models, use of fluorescent tracer materials, and extrapolation from a computer data base of generic pesticide exposure data) that will undoubtedly be receiving increased attention in the future. 

So we began by looking at the possibility of developing a generic exposure data base for at least the limited group, mixer-loader/applicators. This group was a good candidate because the exposure values as defined above are primarily dependent on the physical parameters involved In the application process such as ... 

There are many more exposure studies done in private industry and by government agencies than the number available In the published literature. It Is the data In these studies which offers the best hope for constructing a viable data base for predicting mlxer-loader/applicator exposures. The benefits are clear In cost and time savings. There Is a limit In any society to the amount of resources that can be spent on risk assessment. It would be far better to Jointly apply those resources to areas where data Is Inadequate or where the data will provide more usable information for risk assessment. Mlxer-loader/applicator data offers a special opportunity to test this premise because It can be reported and used on a generic basis which would Improve the quality of risk assessments while at the same time minimize the potential loss of proprietary Information and cost to companies. 

We are, therefore, proposing that a generic field exposure data base be developed using all of the data available which meets the scientific criteria for adequacy whether It be from the literature, the government, government contracts, universities or private Industry. However, In order to accomplish this, two primary needs must be met. 

We have done several field tests on trorker exposure and have constantly modified our methods to improve the utility and statistical reliability of the data and to lay a data base foundation for developing a generic approach to estimation of exposure levels. 

HONEYCUTT Exposure Estimates Based on Generic Data... 

Finally, the MOS should also take into account the uncertainties in the estimated exposure. For predicted exposure estimates, this requires an uncertainty analysis (Section 8.2.3) involving the determination of the uncertainty in the model output value, based on the collective uncertainty of the model input parameters. General sources of variability and uncertainty in exposure assessments are measurement errors, sampling errors, variability in natural systems and human behavior, limitations in model description, limitations in generic or indirect data, and professional judgment. 

By any standards, THC must be considered to be very safe, both acutely and during long-term exposure. This probably partly reflects the fact that cannabinoid receptors are virtually absent from those regions at the base of the brain that are responsible for such vital functions as breathing and blood pressure control. The available animal data are more than adequate to justify its approval as a human medicine, and indeed it has been approved by the FDA for certain limited therapeutic indications (generic name = dronabinol) (9). 

The UK-POEM database is based on a review of the data available on the exposure of pesticide spray operators (in the UK). The review indicated that several factors determined the dose absorbed by a spray operator. These included the following the volume of external contamination, the extent to which this external contamination penetrated clothing to reach the skin and the rate at which the chemical came into direct contact with the skin surface and was absorbed (JMP, 1986 Martin, 1990). These various independent factors were assumed, with the exception of dermal absorption, to be of a sufficient generic nature to be suitable for extrapolation purposes. Two major work activities were differentiated mix-ing/loading and application. An update of the default values in UK-POEM has been presented (POEM, 1992). 

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