INRS activities on risk assessment of glycol ethers.
The occupational exposure assessment uses data from published sources, from Industry (most often from the producers), and from dedicated occupational exposure data bases, as well as evaluations using the EASE model (Estimation and Assessment of Substance Exposure). Atmospheric concentrations and characteristics of skin contacts are evaluated in different scenarios (such as manufacturing, formulating, main and most polluting uses) and sub-scenarios (e.g. warm water dilution). Air concentrations of EGBE are low during production (most often <0.5 mg/m(3)), incidental excursions being <50 mg/m(3); the "worst-case" mean concentration is proposed as 9 mg/m(3). Skin contact, according to EASE, may be in the range of 0-0.1 mg/cm(2)(day), and should be mitigated by the use of suitable gloves. For formulations of products containing EGBE, air concentrations are evaluated as 10 mg/m(3) and skin contact as 0.19 mg/cm(2)(day). The "reasonable worst case" air concentrations (8-Hr TWA) are assessed at around 11 mg/m(3) (coating industry), from 5 to 20 mg/m(3) in printing activities (depending on the task), and in the 20-70 mg/m(3) range (upper limit 40 mg/m(3) in better controlled situations) for cleaning activities. Skin contact would be around twice the preceding level, i.e., 0.4 mg/cm(2)(day) for coating as well as cleaning activities. EGBE and its major metabolites, 2-butoxyacetaldehyde (2-BAL) and 2-butoxyacetic acid (2-BAA) have been subjected to tests for genetic toxicity tests both in vitro and in vivo. While some positive responses have been obtained, the balance of the evidence indicates that EGBE does not express significant genotoxic activity. There are no epidemiological data investigating a relationship between exposure to EGBE and human cancer. Two carcinogenicity inhalation bioassays have been conducted in rodents, one in rats and one in mice. Significant increases were found in forestomach tumours in female mice and haemangiosarcomas in male mice. No increases in tumour incidences were found in either male or female rats. Mechanistic studies have suggested the crucial involvement in the pathogenesis of haemangiosarcomas of a chain of events consisting of (1) haemolysis due to BAA, followed by (2) hepatic haemosiderin deposition and (3) the subsequent generation of reactive oxygen species within the endothelial cells from which haemangiosarcomas arise. Since human erythrocytes are particularly resistant to the haemolytic effects of BAA, it is extremely unlikely, according to this model, that the haemangiosarcomas observed in male mice will have human significance. Similarly, mechanistic studies on the female mouse forestomach tumours have suggested that these also are not important as an indication of human risk. In vivo, EGBE tested in a continuous breeding study and in repeated dose toxicity tests, did not produced specific effects on reproductive organs or fertility parameters. For developmental toxicity, rats, mice and rabbits were dosed via oral and/or inhalation routes. Foeto- and embryo-toxicity was observed in presence or maternal toxicity (haemolytic anaemia). The data available give plausible support to the hypothesis that this developmental toxicity is a direct consequence of maternal toxicity. There are no epidemiological data investigating a relationship between exposure to EGBE alone and human reproductive effects.