Recruiting Strategy and 24-Hour Biomonitoring of Paraquat in Agricultural Workers

Abstract

The objectives of this study were to recruit agricultural workers in Costa Rica to participate in a 24-hour urine collection for paraquat exposure assessment and to compare the 24-hour sampling to endof-shift sampling. The authors recruited 187 handlers and 54 nonhandlers from coffee, banana, and palm oil plantations. The completeness of 24-hour urine samples collected (a total of 393 samples) was confirmed by questionnaire and urinary creatinine level. For a subset of 12 samples, the absorbed paraquat level was determined in 24-hours and end-of-shift spot urine samples. The participation rate for handlers was ~90%. The completeness of 24-hour urine collections was verified as the overall average of creatinine levels from 393 urines (1.11 ± 0.50 g/L). A total of 92.4% to 96.7% of urine samples were considered within the acceptable range of urinary creatinine, whereas 94.7% of the samples were described as "complete" from the questionnaire. Measured creatinine correlated well to predicted values (r = .327, p = .0024, 95% CI .12-.51). Detected paraquat levels in spot urine samples had a sensitivity of 96.9% at the high specificity of 100% compared to 24-hour urine samples as the gold standard. There was a significant (p < .0001) correlation between spot and 24-hour urine paraquat levels (r = .7825, 95% CI .61-.88). The recruiting strategy was successful in getting 24-hour urine samples from a farm worker population. Comparison between the paraquat levels in spot and 24-hour urine samples demonstrated that for this compound, end-of-shift spot urine samples would be an appropriate substitute for 24-hour collections.

Chronic pesticide mixture exposure including paraquat and respiratory outcomes among Colombian farmers

“…Nevertheless, this study quantified biomarkers in urine, which was not often done in previous studies. It is important to remember that previous evidence has found that quantifying paraquat in a single micturition after exposure, as done by the present study, is highly correlated with quantifications using samples of 24-h urine 24) . Bias related to the health of the workers may also exist given the method used to recruit participants.…”