Perspiration increased human pesticide absorption following surface contact during an indoor scripted activity program

Abstract

Homeowners and professional applicators frequently use chemicals to control insect pests in urban environments. The identification and evaluation of determinants of human exposure are critical to conduct reliable and responsible human exposure assessments following indoor residential chemical applications. The effect of sweat on absorbed dose in humans was evaluated with human volunteers who participated in a structured activity program (SAP). Participants (n ¼ 20) performed a warm-up exercise to induce light sweating prior to an SAP on chlorpyrifos(cp)-treated nylon carpet. Absorbed daily dosages (ADDs) were calculated using urinary biomonitoring of trichloropyridinol. In two separate exposures, participation in the warm-up exercise prior to the exposure SAP resulted in an increased ADD of CP equivalents by approximately 50%. Measured ADDs averaged 2.8 (SAP 1) and 2.0 (SAP 2) mg CP equivalents/kg/day in volunteers who participated in the warm-up exercise. In participants who rested prior to the exposures, ADDs were significantly lower at 1.9 (SAP 1) and 1.3 (SAP 2) mg CP equivalents/kg/day. Perspiration may also be a determinant of exposure in active children and field workers. Measured ADDs were less than estimates of ADD made from environmental measurements including CP deposition, the California roller, and clothing dosimeters worn by participants.

Biomonitoring of chlorpyrifos exposure and health risk assessment among applicators on rice farms in Ghana

“…The half-life of chlorpyrifos (50 hours) determined in the present study is higher than those reported in previous studies, which ranges from 27 to 43 hours (Griffin et al 1999;Meuling et al 2005;Nolan et al 1984;Wang et al 2016;Williams et al 2004). The longer half-life found in the present study could be attributable to the octanol/water partition coefficient of the compound.…”

“…These findings have important implications for the design of biomonitoring programs to evaluate chlorpyrifos levels among applicators. Exposure to chlorpyrifos has often been evaluated based on urinary TCP levels obtained from the start of application up to 120 hours (5 days) post-application or less (34 hours) (Alexander et al 2006;Griffin et al 1999;Meuling et al 2005;Nolan et al 1984;Phung et al 2012b;Rodriguez et al 2006;Williams et al 2004). The measurements obtained within these sampling periods would likely under-estimate the levels of chlorpyrifos exposure, since its elimination would still be ongoing beyond these time periods.…”

Outcome of the public consultation on the draft guidance on dermal absorption and the draft scientific opinion on the science behind the revision of the guidance document on dermal absorption

“…They only act after the compound has passed through the epidermis to the vascular dermis, hence they appear to vary with the physical and chemical parameters of the molecule (WHO, 2006;Gordon and Leon, 2005;Tanner and Marks, 2008;Monteiro-Riviere, 2008). Sweating/skin hydration have been reported to increase dermal absorption (Gordon and Leon, 2005;Williams et al, 2004;WHO 2006) as has ambient temperature but the overall magnitude is reported to be < 2 fold (Gordon and Leon, 2005) except when occlusion was applied causing up to 9-fold increases (reviewed by Kezic and Nielsen, 2009). It can be argued that contamination by pesticide formulations/dilutions under the gloves may mimic occlusive conditions.…”

Proposal for a Revision of the Guidance Document on Dermal Absorption

“…Operator exposure models are underpinned by data from whole body exposures, taking account of the relative areas of the high dermal absorption sites it is considered that the use of data generated following exposures of torso / breast skin will provide realistic dermal absorption values for use in exposure modelling. (Gordon & Leon, 2005;Williams et al, 2004;WHO 2006) as has ambient temperature but the overall magnitude is reported to be <2 fold (Gordon & Leon, 2005). Treatment of skin, in vivo and in vitro with an irritant such as sodium lauryl sulphate (SLS) has been shown enhance dermal absorption / penetration (Nielsen, 2005;Danish EPA, 2009) the magnitude of the enhancement (2 to >100 fold) varying with compound and the experimental procedure.…”