title: Assessment of di (2-ethylhexyl) phthalate exposure by urinary metabolites as a function of sampling time.
abstract: OBJECTIVE
  In most DEHP exposure assessment studies, single spot urine sample was used. It could not compare the exposure level among studies. Therefore, we are going to represent the necessity of selection of proper sampling time of spot urine for assessing the environmental DEHP exposure, and the association urinary DEHP metabolites with steroid hormones.
  
  
  METHODS
  We collected urine and plasma from 25 men. The urine sampling times were at the end of the shift (post-shift) and the next morning before the beginning of the shift (pre-shift). Three metabolites of DEHP {mono(2-ethylhexyl) phthalate [MEHP], mono-(2-ethyl-5-hydroxyhexyl)phthalate [MEHHP], and mono(2-ethyl-5-oxohexyl)phthalate [MEOHP]} in urine were analyzed by HPLC/MS/MS. Plasma luteinzing hormone, follicle stimulating hormone, testosterone, and 17ß-estradiol were measured at pre-shift using a ELISA kit. A log-transformed creatinine-adjusted urinary MEHP, MEHHP, and MEOHP concentration were compared between the post- and pre-shift. The Pearson's correlation was calculated to assess the relationships between log-transformed urinary MEHP concentrations in pre-shift urine and hormone levels.
  
  
  RESULTS
  The three urinary metabolite concentrations at post-shift were significantly higher than the concentrations in the pre-shift (p<0.0001). The plasma hormones were not significantly correlated with log-transformed creatinine - adjusted DEHP metabolites.
  
  
  CONCLUSIONS
  To assess the environmental DEHP exposure, it is necessary to select the urine sampling time according to the study object. There were no correlation between the concentration of urinary DEHP metabolites and serum hormone levels.
authors.affiliation: Department of Preventive Medicine, College of Medicine, Chung-Ang University, Korea.
authors.forename: Moon-seo
authors.initials: MS
authors.lastname: Park
authors.forename: Yun-jung
authors.initials: YJ
authors.lastname: Yang
authors.forename: Yeon-pyo
authors.initials: YP
authors.lastname: Hong
authors.forename: Sang-yon
authors.initials: SY
authors.lastname: Kim
authors.forename: Yong-pil
authors.initials: YP
authors.lastname: Lee
mesh_terms: D000328:Adult; D004051:Diethylhexyl Phthalate / Q000031:analogs & derivatives / Q000493:pharmacokinetics / Q000652:urine*; D004958:Estradiol / Q000097:blood; D005640:Follicle Stimulating Hormone / Q000097:blood; D006801:Humans; D007754:Laboratories, Dental; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008875:Middle Aged; D016273:Occupational Exposure / Q000032:analysis*; D010795:Phthalic Acids / Q000652:urine; D013048:Specimen Handling / Q000379:methods*; D013739:Testosterone / Q000097:blood; D013997:Time Factors
chemical_list: D010795:Phthalic Acids; C479069:mono(2-ethyl-5-hydroxyhexyl) phthalate; D013739:Testosterone; C080276:mono(2-ethyl-5-oxohexyl)phthalate; D004958:Estradiol; D007986:Luteinizing Hormone; D005640:Follicle Stimulating Hormone; D004051:Diethylhexyl Phthalate; C016599:mono-(2-ethylhexyl)phthalate