Australian waterways near heavy road traffic may contain 6PPD


A substance known to be toxic to aquatic species is likely to be found in Australian waterways “wherever there are significant traffic-related sources”, says the lead author of a study that reported the existence of concentrations of 6PPD-quinone in the country for the first time.

The substance, a transformation product derived from 6PPD, an antioxidant/antiozonant commonly used in the rubber industry, particularly in car tyres, is new to Australian scientists.

The study – Concentrations of tire additive chemicals and tire road wear particles in an Australian urban tributary – was conducted by a team from the University of Queensland’s Alliance for Environmental Health Sciences (QAEHS) and published in January.

Research in the US indicates that n-(1,3-dimethylbutyl)-n’-phenyl-1,4-benzenediamine (6PPD), used as an anti-wear compound in tyres, gives rise to 6PPD-quinone, which could wash into streams during storms.

The scientists carried out tests at a tributary of the Brisbane River in 2020 during June and October storm events. In every sample taken, 6PPD-quinone was detected at levels comparable to those linked with coho salmon deaths reported by research projects in the US and Canada last year.

Lead author Cassandra Rauert, a research fellow at the QAEHS, said that this is the first time the substance has been reported in Australian waterways.

“While 6PPD-quinone concentrations in this catchment were lower than previous [overseas] studies, elevated concentrations post storm suggest prolonged aquatic exposure,” said Dr Rauert.

Potential risk

“As yet there have been no toxicity studies on vulnerable Australian aquatic life, so we don’t know the potential risk here,” added Dr Rauert. “We still don’t know the full extent of the toxicity of 6PPD-quinone, especially towards Australian species.”

The team will conduct further surveys to ascertain concentrations in different regions of the country and in varying circumstances to understand environmental exposure. It is also working with groups in Europe and the UK investigating leachates from tyre crumb.

“We are not undertaking ecotoxicity studies but there may be other groups in Australia currently looking at vulnerable species,” she said.

A spokesperson from the Department of Agriculture, Water and the Environment (DAWE) told Chemical Watch: “We are not aware of any evidence of toxic effects of 6PPD-quinone on aquatic life in Australia,” adding that it will continue to closely monitor emerging research for any new information on how it may affect aquatic life.

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Chemical Watch, 12-05-22