Priority Substances List Assessment Report for Di-n-Octyl Phthalate

Synopsis

Di-n-octyl phthalate (DnOP), the straight chain dioctyl ester of phthalic acid, is not produced in Canada. Approximately one tonne, however, is used in Canada each year. Din-octyl phthalate has been detected occasionally in industrial liquid effluents and in sewage sludge in Canada, and less frequently in surface waters and sediments. No data have been identified on concentrations of DnOP in air, precipitation, soil, or biota in Canada. This substance is not persistent in air or surface water, but may persist and accumulate in sediment under anaerobic conditions.

The maximum concentration of DnOP reported for surface waters in Canada is approximately five times less than the chronic effects threshold estimated for the most sensitive aquatic species. Although no data were identified on the toxicity of DnOP to wildlife and benthic organisms, it is considered that, on the basis of its limited use, exposure of these organisms is unlikely to result in harmful effects.

Based on the limited use of DnOP in Canada and its rapid removal from the atmosphere by photo-oxidation, concentrations in the atmosphere are likely to be small. Consequently, DnOP is not expected to contribute significantly to formation of ground-level ozone, global warming, or depletion of stratospheric ozone.

The available information was considered inadequate to quantitatively estimate the exposure of the general population in Canada to DnOP or the associated potential health risk.

Based on these considerations, it has been concluded that di-n-octyl phthalate is not entering the environment in a quantity or concentration or under conditions that are having a harmful effect on the environment or that constitute a danger to the environment upon which human life depends. There are insufficient data to conclude whether DnOP is entering the environment in a quantity or concentration or under conditions that constitute a danger to human life or health.