Terbuthylazine in hair as a biomarker of exposure.

Terbuthylazine (TBA) is an herbicide widely used in corn cultivation. Herein we evaluate the measurement of hair TBA as biomarkers of exposure. Five Sprague Dawley rats were gavaged with TBA for 3 days, and then the back hair was shaved and analyzed for TBA. In addition, head hair samples from 10 corn farmers, 9 rural residents, and 6 urban residents were collected at the end of the application season. Hair TBA was detected by liquid chromatography triple quadrupole mass spectrometry after solvent extraction. TBA was quantifiable in all rat samples with a mean concentration of 0.92 (±0.26)ng/mg, which corresponds to a 0.12% incorporation rate. TBA was quantifiable in all farmer samples (median: 0.67ng/mg), in 75% of rural resident samples (0.01ng/mg) and in none of the urban resident samples (<0.01ng/mg), with a statistical difference among groups (P<0.01). Our results suggest that TBA is incorporated in hair and prompt further investigation on the use of hair TBA as a potential biomarker of cumulative exposure.