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Benjamin C. Blount,¹ Manori J. Silva,¹ Samuel P. Caudill,¹ Larry L. Needham,¹ Jim L. Pirkle,¹ Eric J. Sampson,¹ George W. Lucier,² Richard J. Jackson,¹ and John W. Brock¹

¹National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; ²National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, USA

Abstract

Using a novel and highly selective technique, we measured monoester metabolites of seven commonly used phthalates in urine samples from a reference population of 289 adult humans. This analytical approach allowed us to directly measure the individual phthalate metabolites responsible for the animal reproductive and developmental toxicity while avoiding contamination from the ubiquitous parent compounds. The monoesters with the highest urinary levels found were monoethyl phthalate (95th percentile, 3,750 ppb, 2,610 µg/g creatinine) , monobutyl phthalate (95th percentile, 294 ppb, 162 µg/g creatinine) , and monobenzyl phthalate (95th percentile, 137 ppb, 92 µg/g creatinine) , reflecting exposure to diethyl phthalate, dibutyl phthalate, and benzyl butyl phthalate. Women of reproductive age (20-40 years) were found to have significantly higher levels of monobutyl phthalate, a reproductive and developmental toxicant in rodents, than other age/gender groups (p < 0.005) . Current scientific and regulatory attention on phthalates has focused almost exclusively on health risks from exposure to only two phthalates, di-(2-ethylhexyl) phthalate and di-isononyl phthalate. Our findings strongly suggest that health-risk assessments for phthalate exposure in humans should include diethyl, dibutyl, and benzyl butyl phthalates. Key words: exposure, glucuronidase, human, metabolism, phthalates, urine. Environ Health Perspect 108:979-982 (2000) . [Online 1 September 2000]

http://ehpnet1.niehs.nih.gov/docs/2000/108p972-982blount/ abstract.html

Address correspondence to J.W. Brock, National Center for Environmental Health, Centers for Disease Control and Prevention, 4770 Buford Highway MS F-17, Atlanta, GA 30341 USA. Telephone: (770) 488-7839. Fax: (770) 488-4609. E-mail: jwb6@cdc.gov

We thank E. Milgram, C. Hodge, N. Malek, and J. Reidy for assistance with methods development and implementation ; E. Gunter for providing urinary creatinine analysis ; and the National Center for Health Statistics for assistance with demographic information.

This work was partially funded by the National Toxicology Program and the National Institute of Environmental Health Sciences.

Received 26 May 2000 ; 19 July 2000.