Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Exposures of preschool children to chlorpyrifos and its degradation product 3,5,6-trichloro-2-pyridinol in their everyday environments


As part of the Children's Total Exposure to Persistent Pesticides and Other Persistent Organic Pollutants (CTEPP) study, we investigated the exposures of preschool children to chlorpyrifos and its degradation product 3,5,6-trichloro-2-pyridinol (TCP) in their everyday environments. During this study, the participants were still able to purchase and apply chlorpyrifos at their homes or day care centers. Participants were recruited randomly from 129 homes and 13 day care centers in six North Carolina counties. Monitoring was performed over a 48-h period at the children's homes and/or day care centers. Samples that were collected included duplicate plate, indoor and outdoor air, urine, indoor floor dust, play area soil, transferable residues (PUF roller), and surface wipes (hand, food preparation, and hard floor). The samples were extracted and analyzed by gas chromatography/mass spectrometry. Chlorpyrifos was detected in 100% of the indoor air and indoor floor dust samples from homes and day care centers. TCP was detected at homes and day care centers in 100% of the indoor floor dust and hard floor surface wipe, in >97% of the solid food, and in >95% of the indoor air samples. Generally, median levels of chlorpyrifos were higher than those of TCP in all media, except for solid food samples. For these samples, the median TCP concentrations were 12 and 29 times higher than the chlorpyrifos concentrations at homes and day care centers, respectively. The median urinary TCP concentration for the preschool children was 5.3 ng/ml and the maximum value was 104 ng/ml. The median potential aggregate absorbed dose (ng/kg/day) of chlorpyrifos for these preschool children was estimated to be 3 ng/kg/day. The primary route of exposure to chlorpyrifos was through dietary intake, followed by inhalation. The median potential aggregate absorbed dose of TCP for these children was estimated to be 38 ng/kg/day, and dietary intake was the primary route of exposure. The median excreted amount of urinary TCP for these children was estimated to be 117 ng/kg/day. A full regression model of the relationships among chlorpyrifos and TCP for the children in the home group explained 23% of the variability of the urinary TCP concentrations by the three routes of exposure (inhalation, ingestion, dermal absorption) to chlorpyrifos and TCP. However, a final reduced model via step-wise regression retained only chlorpyrifos through the inhalation route and explained 22% of the variability of TCP in the children's urine. The estimated potential aggregate absorbed doses of chlorpyrifos through the inhalation route were low (median value, 0.8 ng/kg/day) and could not explain most of the excreted amounts of urinary TCP. This suggested that there were other possible sources and pathways of exposure that contributed to the estimated potential aggregate absorbed doses of these children to chlorpyrifos and TCP. One possible pathway of exposure that was not accounted for fully is through the children's potential contacts with contaminated surfaces at homes and day care centers. In addition, other pesticides such as chlorpyrifos-methyl may have also contributed to the levels of TCP in the urine. Future studies should include additional surface measurements in their estimation of potential absorbed doses of preschool children to environmental pollutants. In conclusion, the results showed that the preschool children were exposed to chlorpyrifos and TCP from several sources, through several pathways and routes.

Your institute does not have access to this article

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1
Figure 2


  • Adgate J.L., Barr D.B., Clayton C.W., Eberly L.E., Freeman N.C., Lioy P.J., Needham L.L., Pellizzari E.D., Quackenboss J.J., Roy A., and Sexton K. Measurement of children's exposure to pesticides: analysis of urinary metabolite levels in a probability-based sample. Environ Health Perspect 2001: 10(6): 583–589.

    Article  Google Scholar 

  • Bearer C.F. How are children different from adults? Environ Health Perspect 1995: 103(6): 7–12.

    Article  Google Scholar 

  • Chuang J.C., Brinkman M., Hart K., Davis D.B., Finegold J., and Gordon S.M. Method refinement and analysis of food data. Report to USEPA, Contract 68-D4-0023, WA 4-03, 1999.

  • Clayton A.C., Pellizzari E.D., Whitemore R.W., Quackenboss J.J., Adgate J., and Sexton K. Distributions, associations, and partial aggregate exposure of pesticides and polynuclear aromatic hydrocarbons in the Minnesota Children's Pesticide Exposure Study (MNCPES). J Expos Anal Environ Epidemiol 2003: 13(2): 100–111.

    Article  Google Scholar 

  • Cook T.J., and Shenoy S.S. Intestinal permeability of chlorpyrifos using the single-pass intestinal perfusion method in the rat. Toxicology 2003: 184: 125–133.

    CAS  Article  Google Scholar 

  • Curl C.L., Fenske R.A., Kissel J.C., Shirai J.H., Moate T.F., Griffith W., Coronado G., and Thompson B. Evaluation of take-home organophosporus pesticide exposure among agricultural workers and their children. Environ Health Perspect 2002: 110(12): A787–A792.

    CAS  Article  Google Scholar 

  • Davis D.L., and Ahmed A.K. Exposures from indoor spraying of chlorpyrifos pose greater health risks to children than currently estimated. Environ Health Perspect 1998: 106: 299–301.

    CAS  Article  Google Scholar 

  • Exposure Factors Handbook. US Environmental Protection Agency, Office of Health and Environmental Assessment, Washington DC, EPA 600/P-95/002Ba,, 1995.

  • Food and Drug Administration (FDA). Pesticide Program, residue monitoring, 2000.

  • Fenske R.A., Lu C., Barr D., and Needham L. Children's exposure to chlorpyrifos and parathion in an agricultural community in central Washington state. Environ Health Perspect 2002: 110(5): 549–553.

    CAS  Article  Google Scholar 

  • Griffin P., Mason H., Heywood K., and Cocker J. Oral and dermal absorption of chlorpyrifos: human volunteer study. Occup Environ Med 1999: 56: 10–13.

    CAS  Article  Google Scholar 

  • Hanley T.R., Carney E.W., and Johnson E.M. Developmental toxicity studies in rats and rabbits with 3,5,6-trichloro-2-pyridinol, the major metabolite of chlorpyrifos. Toxicol Sci 2000: 53(1): 100–108.

    CAS  Article  Google Scholar 

  • Hines C.J., and Deddens J.A. Determinants of chlorpyrifos exposures and urinary 3,5,6-trichloro-2-pyridinol levels among termiticide applicators. Ann Occup Hyg 2001: 45(4): 309–321.

    CAS  Article  Google Scholar 

  • Koch H.M., and Angerer J. Analysis of 3,5,6-trichloro-2-pyridinol in urine samples from the general population using gas chromatography-mass spectrometry after steam distillation and solid-phase extraction. J Chromatogr B 2001: 759: 43–49.

    CAS  Article  Google Scholar 

  • Landrigan P.J., Claudio L., Markowitz S.B., Berkowitz G.S., Brenner B.L., Romero H., Wetmur J.G., Matte T.D., Gore A.C., Godbold J.H., and Wolff M.S. Pesticides and inner-city children: exposures, risks, and prevention. Environ Health Perspect 1999: 107(3): 431–437.

    CAS  Article  Google Scholar 

  • Lioy P.J., Edwards R.D., Freeman N., Gurunathan S., Pellizzari E., Adgate J.L., Quackenboss J., and Sexton K. House dust levels of selected pesticides and a herbicide measured by the EL and LWW samplers and comparisons to hand rinses and urine metabolites. J Expo Anal Environ Epidemiol 2000: 10: 327–340.

    CAS  Article  Google Scholar 

  • Miller L.A., and Stapleton F.B. Urinary volume in children with urolithiasis. J Urol 1989: 141(4): 918–920.

    CAS  Article  Google Scholar 

  • Needham L.L., and Sexton K. Assessing children's exposure to hazardous environmental chemicals: an overview of selected research challenges and complexities. J Expo Anal Environ Epidemiol 2000: 10: 611–629.

    CAS  Article  Google Scholar 

  • Nolan R.J., Rick D.L., Freshour N.L., and Saunders J.H. Chlorpyrifos: Pharmacokinetics in human volunteers. Toxicol Appl Pharmacol 1984: 73: 8–15.

    CAS  Article  Google Scholar 

  • O'Rourke M.K., Lizardi P.S., Rogan S.P., Freeman N.C., Aguirre A., and Saint C.G. Pesticide exposure and creatinine variation among young children. J Expo Anal Environ Epidemiol 2000: 10: 672–681.

    CAS  Article  Google Scholar 

  • Racke K.D. Environmental fate of chlorpyrifos. Rev Environ Contam Toxicol 1993: 131: 1–150.

    CAS  PubMed  Google Scholar 

  • Rigas M.L., Okino M.S., and Quackenboss J.J. Use of a pharmacokinetic model to assess chlorpyrifos exposure and dose in children, based on urinary biomarker measurements. Toxicol Sci 2001: 61: 374–381.

    CAS  Article  Google Scholar 

  • Ross J.H., Driver J.H., Cochran R.C., Thongsinthusak T., and Krieger R.I. Could pesticide toxicology studies be more relevant to occupational risk assessment? Ann Occup Hyg 2001: 45(1001): S5–S17.

    CAS  Article  Google Scholar 

  • Sexton K., Adgate J.L., Eberly L.E., Clayton C.A., Whitmore R.W., Pellizzari E.D., Lioy P.J., and Quackenboss J.J. Predicting children's short-tem exposure to pesticides: results of a questionnaire screening approach. Environ Health Perspect 2003: 111: 549–553.

    Google Scholar 

  • Szabo L., and Fegyverneki S. Maximum and average urine flow rates in normal children — the Miskolc nomograms. Br J Urol 1995: 76(1): 16–20.

    CAS  Article  Google Scholar 

  • Ting K.C., and Lee C.S. Gas chromatographic determination of triclopyr in fruits and vegetables. J Chromatogr A 1995: 690: 119–129.

    CAS  Article  Google Scholar 

  • Tomlin C.D.S. In The Pesticide Manual. 12th Edn. British Crop Protection Council, UK, 1994, p. 172.

  • USDA. Triclopyr, pesticide fact sheet., 2004.

  • USEPA. Headquarters press release; agreement reached between EPA and chlorpyrifos pesticide registrants., 1997.

  • USEPA. Office of Prevention, Pesticides, and Toxic Substances. Chlorpyrifos revised risk assessment and agreement with registrants., 2000a.

  • USEPA. Office of Pesticide Programs. Chlorpyrifos-methyl summary., 2000b.

  • USEPA. Office of Pesticide Programs. Chlorpyrifos summary., 2000c.

  • USEPA. Office of Pesticide Programs. Chlorpyrifos revised risk assessment and risk mitigation procedures., 2003.

  • Wilson N.K., Chuang J.C., Lyu C., Menton R., and Morgan M.K. Aggregate exposures of nine preschool children to persistent organic pollutants at day care and at home. J Expo Anal Environ Epidemiol 2003: 13(1): 187–202.

    CAS  Article  Google Scholar 

  • Wilson N.K., Chuang J.C., Iachan R., Lyu C., Gordon S.M., Morgan M.K., Ozkaynak H., and Sheldon L.S. Design and sampling methodology for a large study of preschool children's aggregate exposures to persistent organic pollutants in their everyday environments. J Expo Anal Environ Epidemiol 2004: 14: 260–274.

    CAS  Article  Google Scholar 

Download references


We thank the children, adult caregivers, and staff at the child day care centers for their participation in the study. We would also like to thank Battelle staff members, particularly Drs. Robert A. Lordo and Ying L. Chou, for their valuable contribution to the success of this large children's exposure study. Disclaimer: “The United States Environmental Protection Agency through its Office of Research and Development funded and managed the research described here under Contract #68-D-99-011 to Battelle. It has been subjected to Agency review and approved for publication.”

Author information

Authors and Affiliations


Corresponding author

Correspondence to Marsha K Morgan.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Morgan, M., Sheldon, L., Croghan, C. et al. Exposures of preschool children to chlorpyrifos and its degradation product 3,5,6-trichloro-2-pyridinol in their everyday environments. J Expo Sci Environ Epidemiol 15, 297–309 (2005).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:


  • preschool children
  • homes
  • day care centers
  • chlorpyrifos
  • 3,5,6-trichloro-2-pyridinol
  • media

Further reading


Quick links