The federal government has made a recommendation to add Disperse Yellow 3 – an azo disperse dye – to Schedule 1 (List of Toxic Substances) under CEPA 1999.
Disperse Yellow 3 is primarily used in textile facilities for the dyeing of polyester, polyester blends, nylon, cellulose fibres and acrylics in Canada. Disperse Yellow 3 does not dissolve readily in water and is often in the form of crystals of varying sizes. According to the supporting documentation this dye frequently ends up in municipal wastewater streams, since most textile mills offer little or no pre-treatment.
According to the Canada Gazette, Disperse Yellow 3 was identified in the screening assessment as having the potential to cause cancer, based on evidence of increased tumours in rats and mice from a study by the United States National Toxicology Program.
The Canadian Water and Wastewater Association (CWWA) said that while it supports the elimination of known environmental and human health threats, it’s important that, in this case, the dye is managed at the textile mill either by application techniques that reduce the amount of waste dye, or by using alternatives. The CWWA also said that, in consultation with its Wastewater and Stormwater Committee, many municipalities may already have discharge limits as part of their municipal by-laws.