Water Quality Standards

Summary information extracted from: Guidelines for drinking-water quality, 2nd ed. - Vol. 1. Recommendations. - Geneva, World Health Organization, 1993. p. 66.

The primary sources of ethylbenzene in the environment are the petroleum industry and the use of petroleum products.

Because of its physical and chemical properties, more than 96% of ethylbenzene in the environment can be expected to be present in air. Values of up to 26 µg/m3 in air have been reported. It is found in trace amounts in surface water, ground water, drinking-water, and food.

Ethylbenzene is readily absorbed by oral, inhalation, or dermal routes. In humans, storage in fat has been reported. Ethylbenzene is almost completely converted to soluble metabolites, which are excreted rapidly in urine.

The acute oral toxicity is low. No definite conclusions can be drawn from limited teratogenicity data. No data on reproduction, long-term toxicity, or carcinogenicity are available. Ethylbenzene has shown no evidence of genotoxicity in in vitro or in in vivo systems.

A TDI of 97.1 µg/kg of body weight was derived using a NOAEL of 136 mg/kg of body weight per day, corrected for 5 days per week dosing, based on hepatotoxicity and nephrotoxicity observed in a limited 6-month study in rats, and applying an uncertainty factor of 1000 (100 for inter- and intraspecies variation and 10 for the limited database and short duration of the study). This yields a guideline value of 300 µg/litre (rounded figure), allocating 10% of the TDI to drinking-water. This value exceeds the lowest reported odour threshold for ethylbenzene in drinking-water (see Acceptability aspects).