Influence of tea and coffee on biomonitoring of toluene exposure.
BACKGROUND
The intake of some benzoic acid-containing foods or drinks such as green tea and coffee is known to increase urinary hippuric acid (HA) concentrations, and, unless this can be accounted for, may result in false-positive findings during the biological monitoring of toluene exposure.


OBJECTIVE
To investigate the influence of green tea and coffee ingestion on urinary HA concentrations.


METHODS
Time-weighted average exposures to toluene were monitored by measuring urinary HA in 245 car painters in 2005 and again in 2006. Samples of both urine and blood were collected during work hours. All the participants were also asked about their alcohol intake, smoking and dietary and beverage habits, especially green tea and coffee. To clarify the relationship between green tea and coffee ingestion, workers were prohibited from consuming green tea and coffee for 1 day before the health check-up in 2006.


RESULTS
The frequency of positive urinary HA concentrations (>1.0 g/l) in heavy consumers of green tea and/or coffee was significantly higher than that of the non-consumer or light consumers (OR 2.34, 95% CI 1.15-4.74). Prohibiting green tea and coffee ingestion was effective in decreasing the frequency of falsely elevated urinary HA concentrations (P < 0.01).


CONCLUSIONS
The consumption of green tea and/or coffee can result in an overestimation of urinary HA concentrations and cause false-positive results during the biological monitoring of workers exposed to low doses of toluene.
mmunaka@mail.nissan.co.jp
Masahiro
M
Munaka
Takahiko
T
Katoh
Kiyotaka
K
Kohshi
Satomi
S
Sasaki
D000328:Adult; D000428:Alcohol Drinking; D019817:Benzoic Acid / Q000378:metabolism*; D001628:Beverages / Q000032:analysis*; D015415:Biomarkers / Q000652:urine; D002392:Catechin / Q000032:analysis / Q000378:metabolism; D002726:Chlorogenic Acid / Q000032:analysis / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid; D003069:Coffee; D004784:Environmental Monitoring / Q000379:methods; D005189:False Positive Reactions; D006626:Hippurates / Q000652:urine*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016273:Occupational Exposure / Q000032:analysis* / Q000517:prevention & control; D012907:Smoking; D013662:Tea; D014050:Toluene / Q000032:analysis* / Q000378:metabolism; D055815:Young Adult
D015415:Biomarkers; D003069:Coffee; D006626:Hippurates; D013662:Tea; D002726:Chlorogenic Acid; D014050:Toluene; D002392:Catechin; D019817:Benzoic Acid; C030514:hippuric acid