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Biological and air monitoring of chlorpyrifos exposures among termiticide applicators: application of mixed-effect models to evaluate exposure determinants.

Hines C; Deddens J
American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California. Fairfax, VA: American Industrial Hygiene Association, 2002 Jun; :17
Biological and air monitoring was conducted for 41 termiticide applicators in North Carolina using chlorpyrifos. These exposure data were linked to detailed information on chemical use, tasks, personal protective equipment and hygiene in order to identify determinants of chlorpyrifos air exposures and urinary 3,5,6-trichloro-2-pyridinol (TCP) levels. Air and urine samples were collected on multiple days within one week from each applicator. Air samples were analyzed for chlorpyrifos according to NIOSH Method 5600. Urine samples were analyzed for TCP by gas chromatography with mass-selective detection. During the 202 applicator-days monitored, 415 treatment jobs were performed. Full-shift chlorpyrifos air exposures ranged from <0.048 to 110 flg/m3 (n=184), with a geometric mean (GM) of 10 flg/m3. TCP levels ranged from 9.42 to 1960 flg/g creatinine (n=271) and varied significantly by day of the week (GM range: 169-262 flg/g creatinine). Predictive models for chlorpyrifos air exposure and urinary TCP levels were developed using mixed- effects stepwise linear regression. Determinants of airborne chlorpyrifos exposure included minutes chlorpyrifos applied and enclosed crawl space treated (yes/no). Determinants of TCP levels (depending on the model) included day-of-the-week, the chlorpyrifos air concentration one and two days before urine collection, minutes of chlorpyrifos applied one and two days before urine collection, enclosed crawl space treated (yes/no), and commercial structure treated (time-weighted). Within- and between-worker variability was similar for airborne chlorpyrifos; however, for TCP, between-worker variability exceeded within-worker variability by six-fold. The elimination half-life of TCP (26.9 h) and possibly the short sampling interval (one week) may explain the low TCP within-worker variability. Applicators' weekly mean In(TCP levels) and weekly mean In(chlorpyrifos air concentrations) were highly and positively linearly correlated (r2=O.73, p<O.OOO I). In summary, mixed-effects models were successfully constructed to predict airborne chlorpyrifos exposure and urinary TCP levels.
Biological-factors; Biological-monitoring; Air-monitoring; Exposure-levels; Models; Air-samples; Urinalysis; Gas-chromatography
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American Industrial Hygiene Conference and Exposition, June 1-6, 2002, San Diego, California
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division