title: Urinary levels of insecticide metabolites and DNA damage in human sperm.
abstract: BACKGROUND
  Members of the general population are exposed to non-persistent insecticides at low levels. The present study explored whether environmental exposures to carbaryl and chlorpyrifos are associated with DNA damage in human sperm.
  
  
  METHODS
  Subjects (n=260) were recruited through a Massachusetts infertility clinic. Individual exposures were measured as spot urinary metabolite concentrations of chlorpyrifos [3,5,6-trichloro-2-pyridinol (TCPY)] and carbaryl [1-naphthol (1N)], adjusted using specific gravity. Sperm DNA integrity was assessed by neutral comet assay and reported as comet extent, percentage DNA in comet tail (Tail%) and tail distributed moment (TDM).
  
  
  RESULTS
  A statistically significant increase in Tail% was found for an interquartile range (IQR) increase in both 1N [coefficient=4.1; 95% confidence interval (CI) 1.9-6.3] and TCPY (2.8; 0.9-4.6), while a decrease in TDM was associated with IQR changes in 1N (-2.2; -4.9 to 0.5) and TCPY (-2.5; -4.7 to -0.2). A negative correlation between Tail% and TDM was present only when stratified by comet extent, suggesting that Tail% and TDM may measure different types of DNA damage within comet extent strata.
  
  
  CONCLUSIONS
  Environmental exposure to carbaryl and chlorpyrifos may be associated with increased DNA damage in human sperm, as indicated by a change in comet assay parameters.
authors.affiliation: Department of Environmental Health, Harvard School of Public Health, Massachusetts General Hospital, Boston, MA 02115, USA.
authors.forename: John D
authors.initials: JD
authors.lastname: Meeker
authors.forename: Narendra P
authors.initials: NP
authors.lastname: Singh
authors.forename: Louise
authors.initials: L
authors.lastname: Ryan
authors.forename: Susan M
authors.initials: SM
authors.lastname: Duty
authors.forename: Dana B
authors.initials: DB
authors.lastname: Barr
authors.forename: Robert F
authors.initials: RF
authors.lastname: Herrick
authors.forename: Deborah H
authors.initials: DH
authors.lastname: Bennett
authors.forename: Russ
authors.initials: R
authors.lastname: Hauser
mesh_terms: D000328:Adult; D012721:Carbaryl / Q000633:toxicity / Q000652:urine; D004390:Chlorpyrifos / Q000633:toxicity / Q000652:urine; D020552:Comet Assay; D004249:DNA Damage; D004785:Environmental Pollutants / Q000378:metabolism / Q000633:toxicity / Q000652:urine; D006801:Humans; D007306:Insecticides / Q000378:metabolism / Q000652:urine*; D008297:Male; D012044:Regression Analysis; D012907:Smoking; D013082:Sperm Tail / Q000187:drug effects; D013094:Spermatozoa / Q000187:drug effects / Q000502:physiology*
chemical_list: D004785:Environmental Pollutants; D007306:Insecticides; D004390:Chlorpyrifos; D012721:Carbaryl