Assessment of 2,3,7,8‐tetrachlorodibenzo‐p‐dioxin exposure using a modifiedD‐glucaric acid assay

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Abstract
An enzyme‐inhibition assay was evaluated and modified to quantify D‐glucaric acid in a population exposed to 2,3,7,8‐tetrachlomdibenzo‐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.