Dimethoate absorption: A complementary in vitro and in vivo assessment.

This work attempts to evaluate dermal exposure (DE) of farm workers to dimethoate after 4 h of routine application to a lemon plantation. Dimethoate was measured on the workers' clothes as well as in stratum corneum (SC) and in saliva. In vitro permeation tests (IVPT) were performed through rat, pig and human skin and pig buccal, esophageal and sublingual mucosas. The mean of dimethoate DE was 342.19 ± 487.14 mg/d, the percentage of toxic dose per hour was higher than the other pesticides, and the SC penetration factors ranged between 0.5 and 14.81 and 0.05-53.96 % for back of neck and arms respectively. In the supporting IVPT study, dimethoate absorption through human skin was 14.75 % and the default value in the absence of experimental data for this product is 70%. These results show that in family farming the deficiency of correct clothing during the application of pesticides leaves workers more vulnerable.

A proposed eye ex vivo permeation approach to evaluate pesticides: Case dimethoate.

This study aims to propose different ex vivo methodologies for pesticide evaluation when in contact with ocular mucosa. The first ex vivo study was performed using vertical Franz cells with fresh and refrigerated excised bovine corneas. The second evaluated the permeation through the cornea by using fresh, refrigerated and damaged whole bovine eyes. Both experiments were evaluated by applying 50 µl (of 5 mg/ml solution) of an emulsifiable pesticide formulation (Dimetoato 500 EC®). In the first study, dimethoate profiles and permeation fluxes showed no statistical differences (p < .05) between fresh and refrigerated excised corneas, probably due to the excision procedure generating damage to the cornea by altering stromal structure, irrespective of the refrigeration procedure. In relation to the results obtained for developed ex vivo permeation method in whole eyes, there was a statistical difference (p < .05) between experiments performed with fresh eyes and those performed with refrigerated/damaged eyes. Damage generated by both the refrigeration process and exposure to irritant products led to a five-fold reduction in the amount of corneal-permeated pesticide as well as a two-fold increase in retention. Thus, the ex vivo permeation approach with whole eyes seems to be a simple and reproducible method to evaluate pesticides. It is evident that further evaluations need to be performed using other pesticides with distinct physicochemical characteristics.