|
1000
|
Abstract/Summary
|
-
The German Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area has re‐evaluated the biological tolerance value at the work place (BAT value) for 2‐butoxyethanol (ethylene glycol monobutyl ether), considering butoxyacetic acid in urine to characterise the internal exposure. Available publications are described in detail. In male and female individuals exposed to 2‐butoxyethanol, irritant effects to eyes, nose and throat as well as a disturbed taste, headaches and vomiting were observed. The main systemic adverse effects of 2‐butoxyethanol are on the haematopoietic system (haemolytic effects), followed by possible teratogenic and testicular effects. In addition, effects on the central nervous system, the liver and the kidneys were discussed. 2‐Butoxyethanol was classified in category 4 for carcinogenic substances. It can pass through the skin so biological monitoring is necessary. Human studies on exposure and effects, however, are still not available. In more recent animal studies for the haemolytic effects a NOAEC of 25 ml 2‐butoxyethanol/m3 after chronic exposure of rats was obtained. In vivo and in vitro data indicate that regarding to the haemolytic effects rats are more sensitive than humans. At 20 ml 2‐butoxyethanol/m3 and the correlating BAT value of 100 mg butoxyacetic acid/l urine, no haemolytic effects are to be expected according to these recent studies. Also no other systemic effects are to be expected, as no prenatal toxicity was observed up to 100 ml 2‐butoxyethanol/m3 and no effects on male reproductive organs occurred even at 125 ml/m3 (rats) or 250 ml/m3 (mice). In addition, the correlation between 100 mg butoxyacetic acid/l urine and 20 ml 2‐butoxyethanol/m3 is supported by a recently available study with individuals. The previous BAT value of 100 mg free butoxyacetic acid/l urine*, which intended to protect against systemic effects (especially haemolytic effects), is therefore retained. The sampling time is at the end of exposure/shift after several previous shifts. A considerable part of the absorbed 2‐butoxyethanol is excreted in the form of the glutamine conjugate of butoxyacetic acid, i. e. N‐butoxyacetyl glutamine varying intra‐ and inter‐individually. According to published data, about twice as much total butoxyacetic acid as free butoxyacetic acid is excreted. Therefore, a further BAT value of 200 mg butoxyacetic acid (after hydrolysis)/l urine* is established for the sum of free and conjugated butoxyacetic acid. These BAT values apply for both 2‐butoxyethanol and 2‐butoxyethylacetate. *no longer valid
|
