The effects of co-exposure to methyl ethyl ketone on the biological monitoring of occupational exposure to N,N-dimethylformamide.
OBJECTIVE
(1) To assess whether urinary N,N-dimethylformamide (U-DMF) is suitable as a biomarker when co-exposure to methyl ethyl ketone (MEK) exists, and to evaluate whether it is suitable as an exposure biomarker of DMF. (2) To examine whether the co-exposure to MEK affects the characteristics of U-NMF and U-DMF. (3) To investigate if the difference in creatinine-adjusted and non-adjusted measurements of urinary biomarkers of DMF exposure is substantial.


METHODS
Personal exposure monitoring of N,N-dimethylformamide (DMF) and MEK on 11 synthetic-leather workers was performed for 5 consecutive days. Daily post-shift urine for each individual was collected and was analyzed for urinary N-methylformamide (U-NMF) and U-DMF levels on both non-adjusted and creatinine-adjusted bases.


RESULTS
Both U-NMF and U-DMF showed significant associations with airborne DMF. Positive and significant associations between U-NMF and U-DMF on either a non-adjusted basis or a creatinine-adjusted basis were found. Satisfactory linear associations ( P<0.01) between all kinds of urinary biomarkers and DMF exposure were found. The co-exposure to MEK exerted more effect on the relationship of airborne DMF to U-DMF than to U-NMF.


CONCLUSIONS
U-DMF is detectable when occupational DMF exposure is near or below the occupational exposure limit of 10 ppm. In view of the performance of sensitivity, specificity, and positive predictive value, U-NMF, in general, is superior to U-DMF. However, on a par with other findings in this and previous studies, U-DMF might be considered as a complimentary biomarker of exposure to DMF in addition to U-NMF. No distinction between creatinine-adjustment or non-adjustment for urine specimens was found in the biological monitoring of DMF exposure. Further exploration of the influence of co-exposure to MEK at higher exposure is warranted.
Graduate Institute of Environmental and Occupational Health, College of Medicine, National Cheng Kung University Medical College, Tainan, Taiwan.
Ho-Yuan
HY
Chang
Tung-Sheng
TS
Shih
Ching-Chang
CC
Cheng
Ching-Yi
CY
Tsai
Jim-Shoung
JS
Lai
Ven-Shing
VS
Wang
D002074:Butanones / Q000652:urine; D003404:Creatinine / Q000652:urine; D004126:Dimethylformamide / Q000378:metabolism; D004784:Environmental Monitoring; D006801:Humans; D016273:Occupational Exposure; D012680:Sensitivity and Specificity
D002074:Butanones; C005222:methylethyl ketone; D004126:Dimethylformamide; D003404:Creatinine