Chronic toxicity of azo and anthracenedione dyes to embryo-larval life stages of the Fathead minnow (Pimephales promelas)

Synthetic dyes are extensively used in many industrial and consumer products, including paper productions, leather tanning, food colouring, personal care products (examples being; hair colour, deodorant etc.). Synthetic dyes are also used in textile paints. No method has been able to completely remove these pollutants from wastewater and 10-15% of the dyes eventually enter aquatic ecosystem.

In Canada as part of the Government of Canada's Chemicals Management Plan (CMP), substances that are used in industries or imported in as products are being assessed for potential human and environmental toxicity. Azo and anthracenedione dyes are among the groups of substances that have been identified as requiring further study. Since azo and anthracenedione dyes may enter Canadian waterways from municipal wastewater effluents (MWWEs), the objective of this study was to examine the potential effect of azo and anthracenedione dyes within the fish species Pimephales promelas (Fathead minnow) and to compare levels of effect to environmental concentrations and concentrations in Canadian waterways from municipal wastewater effluents (MWWEs).

Over the course of three years (2009-2012) samples were collected on condition of anonymity from 162 municipal wastewater treatment plants across Canada. Wastewater treatment plants featuring different methods of wastewater treatment were chosen (primary treatment, aerated lagoon treatment, lagoon treatment, secondary membrane treatment, and secondary activated sludge treatment). All samples were collected during winter, spring, summer and autumn to account for possible seasonal variability.

Embryo-larval exposures are advantageous because the embryological and larval stages are sensitive to toxicant exposure, survival and growth of hatched larvae can also be assessed, and the duration of the exposures is substantially shorter than full lifecycle tests, making these methods more practical when testing numerous compounds. The Fathead minnow embryo-larval was therefore used to examine lethal and sublethal effects of the four anthracenedione and azo dyes in this dataset: Acid Blue (AB80) and Acid Blue 129 (AB129), Disperse Yellow (DY7) and Sudan Red G (SRG).

Supplemental Information

The Chemicals Management Plan (CMP) is a Government of Canada initiative aimed at reducing the risks posed by chemicals to Canadians and their environment. A key element of the Chemicals Management Plan is the monitoring and surveillance of levels of harmful chemicals in Canadians and their environment. Monitoring and surveillance are essential to identify and track exposure to hazards in the environment and associated health implications. Monitoring and surveillance programs provide the basis for making sound and effective public health and environmental health policies and interventions, as well as measuring the efficacy of control measures.

In support of the Chemicals Management Plan, monitoring and surveillance initiatives were established to support Health Canada and Environment and Climate Change Canada scientists, in collaboration with external partners and researchers, to advance our knowledge. This initiative has allowed the Government of Canada to increase its commitment to a number of existing monitoring initiatives, as well as to support new efforts.

For more information on the Chemicals Management Plan, please visit https://www.canada.ca/en/health-canada/services/chemical-substances/chemicals-management-plan.html