Lack of specificity of trans,trans-muconic acid as a benzene biomarker after ingestion of sorbic acid-preserved foods

The benzene metabolite, trans,trans-muconic acid (MA), has been shown to be a sensitive and specific biomarker for ambient benzene exposure levels as low as similar to 0.5 ppm. However, at lower exposure levels, the use of MA as a benzene biomarker Is complicated by the fact that it is also a metabo lite of the food preservative, sorbic acid. To better assess the extent of this: interference, MA was measured in sequential spot urine samples over a 2-day study period from eight volunteers (four adults and two parent-child ren pairs) who consumed two sorbic acid-preserved foods. Large increases in MA concentration were seen after ingestion of both foods. Individual peaks ranged as high as 1673.7 ng/ml (705.3 ng/mg creatinine) in adults and 1752 .1 ng/mg creatinine (1221.3 ng/ml) in children. Ratios of peak to baseline values varied from 2.5 to 60. The average peak in the seven subjects who sh owed an increase in MA after ingestion of the first sorbic acid-containing food was 531.1 ng/ml (693.2 ng/mg creatinine), The average in the seven par ticipants who ingested the second food was 1102.1 ng/ml (795.3 ng/mg creati nine). Twenty-four-hour personal air benzene levels were all low (less than or equal to 5.6 ppb), Substantial variation in MA results were seen in som e males related to creatinine adjustment, These data indicate that sorbic a cid-preserved foods have the potential to cause substantial interference wi th MA as a biomarker for both occupational and environmental benzene exposu re in populations, such as in the United States, where consumption of prese rved foods is common. Development of methods to minimize and/or assess sorb ic acid interference will improve MA specificity in such populations.