| The Relationship of Urinary Metabolites of Carbaryl/Naphthalene and Chlorpyrifos with Human Semen Quality John D. Meeker,1 Louise Ryan,2 Dana B. Barr,3 Robert F. Herrick,1 Deborah H. Bennett,1 Roberto Bravo,3 and Russ Hauser1 1Department of Environmental Health and 2Department of Biostatistics, Harvard School of Public Health, Boston, Massachusetts, USA; 3Centers for Disease Control and Prevention, Atlanta, Georgia, USA Abstract
Most of the general population is exposed to carbaryl and other contemporary-use insecticides at low levels. Studies of laboratory animals, in addition to limited human data, show an association between carbaryl exposure and decreased semen quality. In the present study we explored whether environmental exposures to 1-naphthol (1N) , a metabolite of carbaryl and naphthalene, and 3,5,6-trichloro-2-pyridinol (TCPY) , a metabolite of chlorpyrifos and chlorpyrifos-methyl, are associated with decreased semen quality in humans. Subjects (n=272) were recruited through a Massachusetts infertility clinic. Individual exposures were measured as spot urinary concentrations of 1N and TCPY adjusted using specific gravity. Semen quality was assessed as sperm concentration, percent motile sperm, and percent sperm with normal morphology, along with sperm motion parameters (straight-line velocity, curvilinear velocity, and linearity) . Median TCPY and 1N concentrations were 3.22 and 3.19µg/L, respectively. For increasing 1N tertiles, adjusted odds ratios (ORs) were significantly elevated for below-reference sperm concentration (OR for low, medium, and high tertiles = 1.0, 4.2, 4.2, respectively ; p-value for trend =0.01) and percent motile sperm (1.0, 2.5, 2.4 ; p-value for trend = 0.01) . The sperm motion parameter most strongly associated with 1N was straight-line velocity. There were suggestive, borderline-significant associations for TCPY with sperm concentration and motility, whereas sperm morphology was weakly and nonsignificantly associated with both TCPY and 1N. The observed associations between altered semen quality and 1N are consistent with previous studies of carbaryl exposure, although suggestive associations with TCPY are difficult to interpret because human and animal data are currently limited. Keywords: biological markers, environment, human, pesticides, semen. Environ Health Perspect 112:1665-1670 (2004) . doi:10.1289/ehp.7234 available via http://dx.doi.org/ [Online 7 September 2004]
Address correspondence to R. Hauser, Department of Environmental Health, Occupational Health Program, Harvard School of Public Health, Building 1, Room 1405, 665 Huntington Ave., Boston, MA 02115 USA. Telephone: (617) 432-3326. Fax: (617) 432-0219. E-mail: rhauser@hohp.harvard.edu We thank L. Godfrey-Bailey who recruited the study patients and collected the biological specimens ; J. Frelich who was responsible for data management ; and A. Trisini and R. Dadd, who assisted with manuscript preparation and literature reviews. This work was supported by grants ES09718 and ES00002 from the National Institute of Environmental Health Sciences (NIEHS) , National Institutes of Health (NIH) . Contents are solely the responsibility of the authors and do not necessarily represent the official views of the NIEHS or the NIH. The authors declare they have no competing financial interests. Received 6 May 2004 ; accepted 7 September 2004.
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