Establishing health-based biological exposure limits for pesticides: A proof of principle study using mancozeb

Abstract

Pesticides represent an economical, labor-saving, and efficient tool for pest management, but their intrinsic toxic properties may endanger workers and the general population. Risk assessment is necessary, and biological monitoring represents a potentially valuable tool.Several international agencies propose biological exposure indices (BEI), especially for substances which are commonly absorbed through the skin. Biological monitoring for pesticide exposure and risk assessment seems a natural choice, but biological exposure limits (BEL) for pesticides are lacking.This study aims at establishing equivalent biological exposure limits (EBEL) for pesticides using real-life field data and the Acceptable Operator Exposure Level (AOEL) of mancozeb as the reference.This study included a group of 16 vineyard pesticide applicators from Northern Italy, a subgroup of a more extensive study of 28 applicators. Their exposure was estimated using "patch" and "hand-wash" methodologies, together with biological monitoring of free ethylene-bis-thiourea (ETU) excretion in 24-hour pre-and post-exposure urine samples.Modeling was done using univariate linear regression with ETU excretion as the dependent variable and the estimated absorbed dose as the independent variable.The median skin deposition of mancozeb in our study population was 125 µg, leading to a median absorbed dose of 0.9 µg/kg. The median post-exposure ETU excretion was 3.7 µg.The modeled EBEL for mancozeb was 148 µg of free ETU or 697 µg of total ETU, accounting for around 75% of the maximum theoretical excretion based on a mass balance model. Although preliminary and based on a small population of low-exposed workers, our results demonstrate a procedure to develop strongly needed biological exposure limits for pesticides..

A Critical Scoping Review of Pesticide Exposure Biomonitoring Studies in Overhead Cultures

“…Likewise, in the case of mancozeb, worst-case assumptions resulted in an estimate several hundred times below the AOEL of 0.02 mg/kg bw for the corresponding metabolite (median saturation of 0.01%) [29]. Even the highest individual exposure of workers was still a thousand times below the daily limit, encumbering the reference value of only 1% [31].…”

“…We identified nine articles and six studies with vine as the target culture (Table 2) [24][25][26][27][28][29][30][31][32]. For tree-grown produce, we found eight articles based on five studies (Table 1) [10,19,23,[33][34][35][36][37], two of which referred to apples [35][36][37].…”

“…No reports were found for hops as the target culture. Study data were collected in three regions, namely, North America (three studies [32,[35][36][37]), Europe (seven studies [10,19,[22][23][24][25][26][27][28][29][30][31]34]) and China (one study [33]), with six of these studies confined to a single region only [24][25][26][27]32,33,36,37].…”

“…Generally, the studies distinguished between operators, reentry workers and residents. Operators [24][25][26][27][29][30][31]33,35] and reentry workers [24][25][26][27][28]32,36,37] were considered in six studies and residents in three [10,19,22,23,33,34]. The corresponding cohort sizes varied significantly, with n = 7-170, 1-22 and 54-403 for operators, reentry workers and residents, respectively.…”

“…For tree-grown produce (Table 1), the corresponding active substances covered a range of protective uses and comprised azinphos-methyl (organophosphate insecticide) [36,37], captan (fungicide) [10,19,35], chlormequat (growth regulator) [10,19], chlorpyrifos (insecticide) [10,19], cypermethrin (insecticide) [10,19], deltamethrin (insecticide) [10,19], diquat (herbicide) [10,19], iprodione (fungicide) [10,19], penconazole (fungicide) [10,19,34], pirimicarb (insecticide) [10,19], thiophanate-methyl (fungicide) [10,19,35], benomyl (fungicide) [35] and imidacloprid (insecticide) [33]. Contrastingly, in vine (Table 2), application mainly included fungicides such tebuconazole [24,25], mancozeb [26,[28][29][30][31] and penconazole [27]. Lopez-Galvez et al [32] also investigated the insecticides imidacloprid, clothianidin, thiamethoxam, acetamiprid and thiacloprid.…”