Phthalates

Methods for Measuring Human Exposure

URINARY PHTHALATE METABOLITE LEVELS

The amount of monoester metabolite in the urine for each phthalate is a fraction of the total excreted urinary metabolites (approx. _ in the case of DEHP) and the total amount of all metabolites in the urine is fraction of total internal ingested dose. In the case of DEHP, monoester metabolites in urine represent approx. 1/10th of the ingested dose the last 24 hrs. It is not clear if the amount of monoester metabolite of a phthalate is produced by the same extent by the different routes of exposure. Effects of phthalates in people have not been well studied, research has been done using animal models. XIV

As the primary urinary metabolite, phthalate monoesters are useful biomarkers of a specific phthalate exposure. This provides physicians with a reference range to determine who has had more exposure than the general population. Results are reported as micrograms phthalate monoester per gram of urinary creatinine. Creatinine adjustment corrects for variations in urine volumes. XV

* Source from Center for Disease Control, First National Report on Human Exposure to Environmental Chemicals, January 31, 2003, http://www.cdc.gov/exposurereport/

BLOOD SERUM LEVELS

This outdated method looks at the parent phthalate compounds instead of the metabolite. This method is not viewed as reliable due to these same compounds being used in plastic laboratory equipment and environment, increasing the concern for contamination of sample and unreliable results. XV