Preliminary Study of Phthalate Exposure in Humans Finds Association with Sperm DNA Damage
For immediate release: December 10, 2002
Boston, MA—In a study of the possible association between phthalate exposure and human semen quality, researchers at Harvard School of Public Health’s Occupational Health Program have found an association between monoethyl phthalate (MEP), the metabolite of di-ethyl phthalate, and DNA damage in sperm.
The study currently appears in the online edition of Environmental Health Perspectives, the journal of the National Institute of Environmental Health Sciences, which funded the research. It is available at: http://ehpnet1.niehs.nih.gov/docs/2003/5756/abstract.pdf.
Phthalates are a class of compounds used to hold color and scent in many cosmetics and personal care items such as soaps, detergents, skin preparations and after shave lotions, and they also find their way into food through packaging materials. Di-ethylhexyl phthalate, one form of phthalate, is used to soften a wide range of plastic goods, which includes medical devices. Phthalates are also present in drinking water and air. Federal studies, conducted by the Centers for Disease Control and Prevention (CDC), have found MEP present in more than 75 percent of U.S. subjects sampled.
The researchers, led by Susan M. Duty and Russ Hauser of HSPH, have termed the study preliminary, as it evaluated semen and a single urine sample from a limited number of subjects, just 168 men at an infertility clinic associated with the Vincent Memorial Obstetrics and Gynecology Service, Massachusetts General Hospital. The researchers plan follow-up studies with larger groups of men to confirm the results.
Measurements were made of five different urinary phthalate metabolites, but only one yielded a significant association with sperm DNA damage, and that was MEP, which was found in all of the urine samples and at higher levels than the other metabolized phthalates. The “comet assay” was used to measure DNA integrity in sperm. A sperm cell with fragmented DNA that has been treated with fluorescent dye has the appearance of a “comet” with the relative length of the comet representing increasing DNA damage. The highest levels of urinary MEP were found to be associated with increased comet length. The comet assay is not a measure of DNA mutation.
“This study represents the first human data on a relatively small sample of men,” said Dr. Duty, lead author of the study and a post-doctoral fellow at HSPH. “We found an association between MEP and DNA integrity, a general measure of DNA damage. These findings are interesting and warrant further exploration with a larger sample of men. Although phthalates are found in many products, the relative contribution of phthalates from cosmetics versus other sources of phthalates is unclear, therefore no recommendation can be made at this time concerning the use of phthalates in cosmetics.”
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