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5/4/2001

CDC Reports Higher Levels of Other Phthalates Than of DEHP in Humans, Despite Greater Environmental Exposure

Nancy Tarleton Landis

A new report from the Centers for Disease Control and Prevention (CDC) documents levels of 27 environmental chemicals in human body fluids. For most of those chemicals, this is the first such report of national exposure levels. Among the substances covered in the National Report on Human Exposure to Environmental Chemicals are the phthalates used as plasticizers in vinyl medical products.

Two years ago, a group called Health Care Without Harm (HCWH) captured media attention with its campaign for safer alternatives to polyvinyl chloride (PVC) i.v. bags (see May 15, 1999, AJHP News). Most PVC-containing products use the plasticizer di-2-ethylhexyl phthalate (DEHP). Studies in rodents have associated DEHP exposure with defects in development of the male reproductive system. An October 2000 report from the National Toxicology Program Center for the Evaluation of Risks to Human Reproduction cited concern that high levels of DEHP exposure in human infants and toddlers could adversely affect male reproductive-tract development. The greatest concern was with intensive treatment involving "parenteral medical exposure to DEHP" in critically ill infants.

In March 2001, the California Medical Association adopted a resolution urging hospitals to phase out their use of PVC products containing DEHP in neonatal intensive care units. The resolution was coauthored by Robert M. Gould, president of the San Francisco Bay Area Physicians for Social Responsibility and a member of HCWH. According to HCWH, a committee of the European Union approved a document in March recommending that phthalates be phased out of medical devices.

Now, the CDC findings are prompting new research on how phthalates enter the body and what health risk they present. DEHP and diisononyl phthalate, which also is used to produce flexible plastic products, are the two phthalates produced in greatest quantity, says the environmental exposure report, but urine levels of metabolites of two other phthalates (diethyl phthalate [DEP] and dibutyl phthalate [DBP]) are much higher.

"Health research needs to focus on DEP and DBP, given that the levels of their metabolites are much higher in the general U.S. population," says the report. DEP and DBP are industrial solvents. DEP is used in perfume, cologne, bar soap, shampoo, and hand lotion and DBP in nail polish, cosmetics, and insecticides.

The CDC data come from the 1999 National Health and Nutrition Examination Survey. Blood and urine samples used to establish reference ranges, or background exposure levels, for the chemicals were taken from individuals selected without regard to known exposure. Phthalate metabolites were measured in urine of people age six years or older.

"Measurement of an environmental chemical in a person's blood or urine does not by itself mean that the chemical causes disease," says the report, stressing that duration of exposure is a critical factor. No new data on health risks from different exposure levels are presented. Future reports will track trends in environmental exposure and determine whether exposure levels differ by age, income, or other characteristics.