title: Phthalate exposure and human semen parameters.
abstract: BACKGROUND
  There is scientific and public concern about commonly used chemicals, including phthalates, that are associated with reproductive toxicity in laboratory animals and are hormonally active. People are exposed to phthalates through diet, consumer products and medical devices. The present study explored whether environmental levels of phthalates are associated with altered semen quality in humans.
  
  
  METHODS
  We recruited 168 men who were part of subfertile couples and who presented to the Massachusetts General Hospital andrology laboratory for semen analysis between January 2000 and April 2001. Semen parameters were dichotomized based on 1999 World Health Organization reference values for sperm concentration (< 20 million/ml) and motility (< 50% motile), as well as Tygerberg Strict criteria for morphology (< 4% normal). The comparison group was men for whom these semen parameters were all above the reference values. In urine, eight phthalate metabolites were measured with high-performance liquid chromatography and tandem mass spectrometry. Specific gravity-adjusted phthalate metabolite levels were categorized into tertiles.
  
  
  RESULTS
  There was a dose-response relation between tertiles of mono-butyl phthalate and sperm motility (odds ratio per tertile = 1.0, 1.8, 3.0; P-value for trend = 0.02) and sperm concentration (1.0, 1.4, 3.3; P-value for trend = 0.07). In addition, there was a dose-response relation between tertiles of mono-benzyl phthalate and sperm concentration (1.0, 1.4, 5.5; P-value for trend = 0.02).
  
  
  CONCLUSIONS
  There were dose-response relations for monobutyl phthalate and monobenzyl phthalate with one or more semen parameters, and suggestive evidence for monomethyl phthalate with sperm morphology. The lack of a relation for other phthalates may indicate a difference in spermatotoxicity among phthalates.
authors.affiliation: Department of Environmental Health, Occupational Health Program, Harvard School of Public Health, Boston, MA 02115, USA.
authors.forename: Susan M
authors.initials: SM
authors.lastname: Duty
authors.forename: Manori J
authors.initials: MJ
authors.lastname: Silva
authors.forename: Dana B
authors.initials: DB
authors.lastname: Barr
authors.forename: John W
authors.initials: JW
authors.lastname: Brock
authors.forename: Louise
authors.initials: L
authors.lastname: Ryan
authors.forename: Zuying
authors.initials: Z
authors.lastname: Chen
authors.forename: Robert F
authors.initials: RF
authors.lastname: Herrick
authors.forename: David C
authors.initials: DC
authors.lastname: Christiani
authors.forename: Russ
authors.initials: R
authors.lastname: Hauser
mesh_terms: D000328:Adult; D000818:Animals; D004781:Environmental Exposure / Q000009:adverse effects*; D006801:Humans; D007248:Infertility, Male / Q000139:chemically induced*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010795:Phthalic Acids / Q000633:toxicity* / Q000652:urine; D012016:Reference Values; D012661:Semen / Q000187:drug effects*; D012907:Smoking / Q000009:adverse effects; D013076:Sperm Count; D013081:Sperm Motility / Q000187:drug effects
chemical_list: D010795:Phthalic Acids