Exposure to methyl tert-butyl ether and tert-amyl methyl ether from gasoline during tank lorry loading and its measurement using biological monitoring.
OBJECTIVE
The exposure of Finnish tank lorry drivers to methyl tert-butyl ether (MTBE) and tert-amyl methyl ether (TAME) during loading of gasoline was studied using biological and breathing-zone sampling. During the field measurements in October 1994 and August 1995 the gasolines (95, 98, 99 RON) contained MTBE to 5.2-11.8% and TAME to 0-6%.


RESULTS
The geometric mean (GM) breathing-zone concentration of MTBE was 4.3 mg/m3 (n = 15) in October and 6.4 mg/m3 (n = 20) in August. The GM concentration of TAME, measured only in August, was 0.98 mg/m3. The mean loading/sampling times were 37 and 35 min, the mean wind speeds were 0.8 and 0.6 m/s, and the mean air temperatures were -4.9 degrees and + 14.1 degrees C, respectively. Blood samples collected on average at 20 min after gasoline loading/exposure showed an MTBE concentration of 143 nmol/l (GM, n = 14) in October and 213 nmol/l (GM, n = 20) in August. Pearson's coefficient of correlation (r) between the MTBE breathing-zone concentrations and MTBE in blood was 0.86 (P = 0.0001) in October and 0.81 (P = 0.00001) in August. No correlation was found between MTBE in air and the metabolite tert-butanol (TBA) in blood. MTBE, but not TBA, in urine samples collected on average at 2.5 h after exposure showed a correlation with MTBE in air. The concentrations of TAME and its metabolite tert-amyl alcohol were below the quantitation limits ( < 7 and < 100 nmol/l, respectively) in most blood and urine samples.


CONCLUSIONS
The breathing-zone measurements showed low levels of exposure to the two oxygenates, the concentrations being well below the current hygienic standards for MTBE (250-360 mg/m3 for 15 min and 90-180 mg/m3 for 8 h). The linear correlations obtained for MTBE suggest that MTBE in blood or urine can be adopted as a valid biological exposure index.
Vainiotalo
S
S
Department of Industrial Hygiene and Toxicology, Finnish Institute of Occupational Health, Helsinki. Sinikka.Vainiotalo@occuphealth.fi
Pekari
K
K
Aitio
A
A
D000393:Air Pollutants / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D005240:Feasibility Studies; D005387:Finland; D005742:Gasoline; D006801:Humans; D016014:Linear Models; D008738:Methyl Ethers / Q000032:analysis* / Q000378:metabolism; D016273:Occupational Exposure / Q000032:analysis*; D015203:Reproducibility of Results; D012621:Seasons; D013696:Temperature; D014186:Transportation; D014919:Wind
D000393:Air Pollutants; D005742:Gasoline; D008738:Methyl Ethers; C043243:methyl tert-butyl ether; C096680:tertiary-amyl methyl ether