Assessment of 2,3,7,8-tetrachlorodibenzo-p-dioxin exposure using a modified D-glucaric acid assay

An enzyme-inhibition assay was evaluated and modified to quantify D-glucaric acid in a population exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). The modified assay combined improvements described separately in previous reports, including pH adjustment by standard addition of buffers rather than by titration, an optimum pH of 2.3 for converting D-glucaric acid to 1,4-glucarolactone, and the use of the relation reciprocal of absorbance versus concentration for calculating unknowns. Reference limits for adult males were 0.06-5.90 mmol D-glucaric acid/mol creatinine and for adult females 0.87-6.23 mmol D-glucaric acid/mol creatinine. Children under the age of 15 yr had a reference range of 0-8.34 mmol D-glucaric acid/mol creatinine. Persons on anticonvulsant therapy excreted from 3 to 10 times the upper reference limits of D-glucaric acid. Urinary concentrations of D-glucaric acid in persons identified as being at high risk for exposure to 2,3,7,8-TCDD in Times Beach, Mo., were not significantly different from concentrations in those identified as being at low risk for such exposure.