Operator exposure from closed system loading and application of alachlor herbicide

Abstract

Biological monitoring (urine) and passive monitoring (patch) techniques were used to estimate total body dose in sixteen operators of closed system transfers of the emulsifiable concentrate (EC) and the micro-encapsulated (MT) formulations of alachlor herbicide from prepackaged bulk containers. Four of the operators were also monitored during the subsequent soil incorporation applications. The dermal deposition was very low and, more importantly, the analysis of 12-hour composites of urine collected for five days, revealed undetectable (<5 ppb) concentrations of alachlor metabolites in every sample from 12 of 16 operators. The mean normalized absorbed dose of alachlor was 4.1×10⁻⁷ mg/kg bw/lb applied for EC tank fill plus application, zero (undetected) for EC tank fill only, and 1.1×10⁻⁷ mg/kg bw/lb applied for MT tank fill only. These results demonstrate that operators wearing normal clothing plus protective clothing as recommended on the product label, will experience negligible exposure while using well designed closed transfer systems. The urine samples in this study were analyzed by a new method which utilizes base-pressure hydrolysis to convert the alachlor metabolites to the anilines which are separated by high pressure liquid chromatography (HPLC) and detected by an electrochemical detector.