Mandelic acid is the major metabolite of styrene. Styrene (vinylbenzene) is used as an intermediate in plastic synthesis. Values less than 5 mg/L are due to normal metabolism of phenylalanine or tyrosine.
High concentrations of styrene cause:
- central nervous system depression,
- and liver damage.
When exposed to 100 ppm of styrene in air, mandelic acid in urine was found to average 1700 mmol/mol creatinine. Mandelic acid is also a metabolite of ethylbenzene, and some antispasmodic and vasodilator drugs. High values of mandelic acid also occur in phenylketonuria (PKU). Normal values of phenyllactic and phenylpyruvic acids may rule out PKU; a mild or heterozygous form of PKU might be present.
Measuring serum phenylalanine will rule out PKU.
Other causes may be increased dietary phenylalanine or phenylalanine supplements. Normal phenyllactic and phenylpyruvic acids indicate that styrene or drug exposure is more likely than PKU as a cause of these abnormalities. Dopamine metabolism is a target for the neurotoxic effects of some monocyclic aromatic hydrocarbons and their metabolites.
How to reduce exposure to styrene:
Reduce exposure by eliminating plastic and styrofoam containers for cooking, reheating, eating or drinking (especially warm or hot) food or beverages. Replace these containers with glass, paper, or stainless steel whenever possible.
Elimination of styrene can be accelerated by sauna treatment, reduced glutathione supplementation (oral, intravenous, transdermal, precursors such as N-acetyl cysteine [NAC]).
Ascorbic acid deficiency may also be related to this abnormality since ascorbic acid is a cofactor for phenylalanine hydroxylase. Supplementation with ascorbic acid (vitamin C) at 1000 mg/day or more may be beneficial.
- Significant elevation is found in the genetic disorder, phenylketonuria (PKU). A plasma phenylalanine test will rule out PKU.
- Slight elevations by dietary phenylalanine or phenylalanine supplementation, but also due to exposure to styrene, a toxic environmental compound.
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