Occupational paraquat exposure of agricultural workers in large Costa Rican farms

Int Arch Occup Environ Health. 2009 Mar;82(4):455-62. doi: 10.1007/s00420-008-0356-7. Epub 2008 Sep 2.


Objective: Paraquat is an herbicide widely used worldwide. This study determined the extent of occupational exposure to paraquat among farm workers in Costa Rica and identified determinants of occupational exposure.

Methods: Twenty-four hour urine samples were collected from 119 paraquat handlers and 54 non-handlers from banana, coffee and palm oil farms. Information about herbicide handling operations was also collected. The urinary paraquat levels were determined by an enzyme-linked immunosorbent assay (ELISA) with a limit of quantification (LOQ) of 2 ng/mL. Inhalable dust and airborne paraquat levels were simultaneously measured for a subset of the participants.

Results: Urinary paraquat measurements were non-detectable or very low when workers did not handle paraquat. For handlers, 83.3, 47.1 and 63.9% of the samples were below the LOQ on before-, during- and after-paraquat spray days, respectively. The arithmetic mean (+/-SD) of urinary paraquat level on days when workers handled paraquat was 6.3 (+/-10.45) microg/24 h. Paraquat exposures among handlers on spray day were significantly associated with the type of crop.

Conclusion: Non-handlers had negligible urinary paraquat, while detectable paraquat exposures were observed among handlers on spray day. Urinary paraquat levels were different by crop.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Agriculture
  • Air Pollutants, Occupational / urine
  • Coffee
  • Costa Rica
  • Environmental Monitoring
  • Enzyme-Linked Immunosorbent Assay
  • Herbicides / urine*
  • Humans
  • Inhalation
  • Male
  • Middle Aged
  • Occupational Exposure / analysis*
  • Paraquat / urine*
  • Protective Clothing
  • Regression Analysis
  • Surveys and Questionnaires


  • Air Pollutants, Occupational
  • Coffee
  • Herbicides
  • Paraquat