Chlorpyrifos exposure in farm families: Results from the farm family exposure study

Abstract

We used urinary biological monitoring to characterize chlorpyrifos (O,O-diethyl-O-(3,5,6-trichloro-2-pyridinyl) phosphororthioate) exposure to farm family members from Minnesota and South Carolina who participated in the Farm Family Exposure Study. Five consecutive 24-h urine samples were obtained from 34 families of licensed pesticide applicators 1 day before through 3 days after a chlorpyrifos application. Daily 3,5,6-trichloro-2-pyridinol (TCP) urinary concentrations characterized exposure profiles of the applicator, the spouse, and children aged 4-17 years. Self-reported and observed determinants of exposure were compared to the maximum postapplication TCP concentration. All participants had detectable (> or = 1 microg/l) urinary TCP concentrations at baseline. Applicators' peak TCP levels occurred the day after the application (geometric mean (GM) = 19.0 microg/l). Postapplication TCP change from baseline in the spouses and children was negligible, and the only reliable predictor of exposure was assisting with the application for children aged 12 years and older. The applicators' exposure was primarily influenced by the chemical formulation (GM = 11.3 microg/l for granular and 30.9 microg/l for liquid), and the number of loads applied. Repairing equipment, observed skin contact, and eating during the application were moderately associated TCP levels for those who applied liquid formulations. Estimated absorbed doses (microg chlorpyrifos/kg bodyweight) were calculated based on TCP excretion summed over the 4 postapplication days and corrected for pharmacokinetic recovery. The GM doses were 2.1, 0.7, and 1.0 microg/kg bodyweight for applicators, spouses, and children, respectively. Chlorpyrifos exposure to farm family members from the observed application was largely determined by the extent of contact with the mixing, loading, and application process.

Probabilistic assessment of chlorpyrifos exposure to rice farmers in Viet Nam

“…6,25,26 However, the time for chlorpyrifos ADD A as represented by urinary TCP to decline to the baseline level differed from that observed in previous studies. With Sri-Lankan and USA farmers, this decline to baseline occurred in approximately 96 h 6,25,26 ).…”

“…6,25,26 However, the time for chlorpyrifos ADD A as represented by urinary TCP to decline to the baseline level differed from that observed in previous studies. With Sri-Lankan and USA farmers, this decline to baseline occurred in approximately 96 h 6,25,26 ). The recent study conducted by Farahat et al 24 indicated that urinary TCP concentration returned to the baseline level in excess of 168 h post application among Egyptian cotton farmers.…”

Review of the Toxicology of Chlorpyrifos With an Emphasis on Human Exposure and Neurodevelopment

“…2003, Hore et al, 2005Morgan et al 2005) have, on average, urinary TCPy values in the range of 6-8 ppb, or approximately 2-3 times greater than the "background" levels seen in the NHANES II study. Similarly, farmers who applied chlorpyrifos tended also to have urinary TCPy values about twofold greater than the NHANES II "background" levels, suggesting that some exposure to chlorpyrifos does occur (Curwin et al, 2005;Alexander et al, 2006). However, exposures to farm worker families in those same studies did not appear to add substantially to the background levels of TCPy in urine.…”

“…Because this study collected 24-h urine samples rather than spot urine samples, from farmers who applied chlorpyrifos, as well as from their spouses and children, and samples were collected prior to, the day of, and 3 days following application, it represents the most thorough and relevant assessment of chlorpyrifos exposures to date. The results of this exposure assessment study for chlorpyrifos were presented recently (Alexander et al, 2006) and are discussed later.…”

Cholinesterase inhibition in chlorpyrifos workers: Characterization of biomarkers of exposure and response in relation to urinary TCPy

“…Its presence in urine is regarded as a specific marker for exposure to these compounds in the occupational setting, although in the general population it is also a marker for direct exposure to TCPy, mostly from TCPy in food (Morgan et al, 2005). Urinary TCPy is used to assess exposure to CPF in the population at large (Barr et al, 2005;CDC, 2005) and among applicators and their families (Alexander et al, 2006). Urinary TCPy has been measured in epidemiological studies of children (Berkowitz et al, 2004;Eskenazi et al, 2004Eskenazi et al, , 2007, pesticide applicators (Steenland et al, 2000) and manufacturers (Albers et al, 2004a).…”