In Vitro Method to Quantify Dermal Absorption of Pesticide Residues

Dose Setting for Dermal Absorption Studies on Dried Foliar Residues

Currently, the standard approach to estimate systemic exposure of workers after contact with dried pesticide residues on crops during re-entry activities relies on using the highest identified dermal absorption value for aqueous spray dilutions. However, recent dermal absorption studies with dried residues and their respective in-use dilutions have shown that this is likely to significantly overestimate their dermal penetration potential and, thus, predicted systemic exposure. The choice of appropriate dose levels for these dermal absorption studies has not been defined. Moreover, actual skin loading during re-entry tasks may differ significantly from that achieved by applying a fixed volume of an aqueous dilution, which is the standard practice in generic dermal absorption studies. To address this, we propose an approach to dose setting for dried residue studies within the current European risk assessment framework. Skin loading for studies can be calculated from the existing exposure algorithms and by taking appropriate body surface areas into account. Thus, skin loading in studies will vary depending on the exact nature and duration of the task and the region of the body exposed, reflecting actual exposure scenarios.

Pesticide dermal absorption: Case study x in vitro study

In order to evaluate dermal absorption during typical working conditions in family farming, the amount of dimethoate on clothing and in the stratum corneum (SC) was measured in three rural workers. This was achieved by using cotton patches on the worker's clothes and SC quantification by the tape stripping approach. To mimic the above study, an in vitro approach was performed using Franz cells by applying dimethoate (0.4 and 1.8 μg) direct to pig skin or, on a section of cotton before contact with pig skin. The in vivo case results demonstrated the high levels and variability of agrochemicals to which these farmers are subjected, with the total potential dermal absorption between 0.87-2.85 mg/person/h and the estimated SC penetration factor (PF) between 0-54.0 and 0-28.9 % for the back of the neck and the arms respectively. This probably demonstrates the impact of correct protective clothing. For the in vitro study, the amount of pesticide retained in the SC was 52.63 ± 10.73and 135.15 ± 31.8 ng/cm² after applying 0.4 and 1.8 μg of pesticide directly on SC, and demonstrated close agreement with the in vivo approach. Further studies performed with this and other pesticides with different characteristics will contribute to the understanding of their transport through the skin.

The Association Between Skin Rashes and Work Environment, Personal Protective Equipment, and Hygiene Practices Among Female Farmworkers

The objective of this study was to assess work-related hygiene practices and the frequency and location of skin rashes due to cutaneous contact with crop-associated materials (e.g., pesticides) for female nursery and fernery workers in Central Florida. A cross-sectional, community-based participatory research study of 237 female nursery and fernery workers between the ages of 19 and 43 years with significant cutaneous contact with foliage crops was conducted using a self-report questionnaire and a skin rash chart assessment tool. Of the 237 farmworkers surveyed, 37.1% ( n = 88) reported a rash on at least one area of their bodies. Women who were pregnant during the study were 4.7 times more likely to report more than 30% total body surface area (TBSA) covered by rash compared with non-pregnant fernery workers ( p = .045; 95% confidence interval [CI] [1.04, 21.35]). Further research is needed to better understand the development of skin rashes among farmworkers, to generate effective prevention strategies.