Correspondence between occupational exposure limit and biological action level values for alkoxyethanols and their acetates.

OBJECTIVES

The Finnish occupational exposure limit (OEL) values for alkoxyethanols and their acetates were lowered in 1996. A reevaluation of the correspondence between the new OEL value and the biological action level (BAL) was thus needed. This study was conducted in silkscreen printing enterprises, where 2-alkoxyethanols and their acetates are mainly used as solvents. The air/urine correlations between 2-methoxyethylacetate, 2-ethoxyethylacetate, 2-butoxyethanol, 2-butoxyethylacetate, and 2-methoxyacetic (MAA), 2-ethoxyacetic (EAA), and 2-butoxyacetic acid (BAA) were evaluated on an individual and time-related basis at four different enterprises.

METHODS

Inhalation exposure to alkoxyalcohols and their acetates was monitored with diffusion badges (n = 38) for an entire work week. Urinary excretion of alkoxyacetic acids immediatley after the shift and at 14-16 h after exposure (n = 112) was analyzed by a gas chromatograph equipped with a flame-ionization detector.

RESULTS

Inhalation exposure to 2-methoxyethylacetate at 0.5 cm3/m3 corresponded to MAA excretion of 3 mmol/mol creatinine in urine at 14 to 16 hours after exposure. The next-morning urinary EAA excretion of 37 mmol/mol creatinine corresponded to an 8-h 2-ethoxyethylacetate exposure of 2 cm3/m3 when all collected data were included. This average EAA excretion was 69% of the German BAT value and only 34% of the American biological exposure index (BEI) value. Urinary EAA excretion was 30-40% lower at the beginning of the work week than at the end of the work week. On the other hand, EAA excretion was 10-20% higher than that measured at 14-16 h after exposure. Urinary BAA excretion of 75 mmol/mol creatinine in postshift urine corresponded to an 8-h 2-butoxyethanol and 2-butoxyethylacetate exposure of 5 cm3/m3. This BAA excretion was 87% of the German BAT value.

CONCLUSION

According to these results, it seems that the BAL for MAA and EAA should be 3 and 50 mmol/mol creatinine as measured at 14-16 h after exposure, respectively. The BAL value for BAA seems to be 70 mmol/mol creatinine in postshift samples. These recommendations are valid only if samples are collected at the end of the work week.