Recruiting strategy and 24-hour biomonitoring of paraquat in agricultural workers

Eun Kee Park, Hector Duarte Tagles, Shirley Gee, Bruce Hammock, Kiyoung Lee, Marc Schenker

Research output: Contribution to journalArticlepeer-review

2 Scopus citations


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 end-of-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.

Original languageEnglish
Pages (from-to)207-217
Number of pages11
JournalJournal of Agromedicine
Issue number4
StatePublished - 2008
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by Syngenta Research Agreement 002994, the Western Center for Agricultural Health and Safety (NIOSH Cooperative Agreement No. U07/CCU9061202), and NIEHS Superfund Basic Research Program, P42 ES004699. However, it has not been subjected to funding agency review and does not necessarily reflect the views of the funding agency.


  • 24-hour urine
  • Agriculture
  • Biological monitoring
  • Farm worker
  • Paraquat
  • Recruiting strategy


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