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Styrene - PSL1

Synopsis

Approximately 700 kilotonnes of styrene are produced annually in Canada, of which nearly two thirds are exported. Styrene is used domestically in the production of a number of polymers and resins and is released into the Canadian environment, principally into the atmosphere. Although it does not persist in environmental media, measurable concentrations have been reported in ambient air, indoor air and water in Canada, and in some industrial and municipal effluents.

The maximum concentration of styrene measured in air from a rural site in Canada is over 800 times less than the effects threshold estimated for wild mammals exposed by inhalation. Data were insufficient, however, to estimate the possibly significant contribution of other media to the total intake of wildlife. Furthermore, the data identified on effects on aquatic biota were inadequate for assessment.

Styrene has a short atmospheric half-life, and is present at very low concentrations in the atmosphere. Thus, it is not expected to contribute significantly to depletion of stratospheric ozone or to global warming.

Based on data on concentrations in ambient and indoor air, food, drinking water and soil, the average total daily intakes of styrene for various age groups in the general human population have been estimated. Tolerable daily intakes for styrene have been derived based on the effects observed at the lowest levels in laboratory animals (those on the developing foetus) following inhalation and ingestion. (The tolerable daily intake is the dose to which it is considered that humans may be exposed daily over their lifetime without deleterious effect.) The estimated average total daily intake of styrene by various age groups in the Canadian general population is from 50 to 600 times less than these tolerable daily intakes.

Based on these considerations, it has been concluded that the available information is insufficient to determine whether styrene is entering the environment in quantities or under conditions that may be harmful to the environment. It has, however, been concluded that styrene is not entering the environment in quantities or under conditions that may constitute a danger to the environment on which human life depends, or to human life or health.