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A Toxic Risk for Asian Medicine

Consumers of Asian medicine derived from Australian marine life may be inadvertently consuming toxins, according to research that identified the presence of toxic substances in devil and manta rays and traced the trade of these animals across Asia.

“Devil and manta rays are some of the world’s most biologically vulnerable fishes, and their dried gill plates have become a valued commodity in alternative medicine markets,” said Dr Kathy Townsend of The University of Queensland (UQ).

“Vendors recommend gill plates for ailments ranging from acne to cancer, and as a general health tonic, even though it is a new addition to traditional medicine literature and rarely prescribed.”

A UQ study published in Aquatic Conservation: Marine and Freshwater Ecosystems found that Guangzhou in China accounted for 99% of trade in devil and manta rays in 2011. While recent Chinese government policies have since seen the trade of gills decline in mainland China, Hong Kong has experienced dramatic increases.

The most common sources of gill plates are Chinese, Indonesian, Vietnamese, Sri Lankan and Indian waters. While Australian waters are regarded as a high-end product, Townsend last year revealed in Marine Pollution Bulletin that one-quarter of live devil rays caught near Lady Elliott Island in Queensland display lead levels that exceed international food safety standards.

“It could be linked to the large-scale mining activities in Queensland, inland from the Great Barrier Reef,” Townsend said. “Australia is one of the world’s largest producers of lead, and lead mining has been identified as a major cause for concern for environmental contamination. Other marine organisms in the Great Barrier Reef have been found to be similarly affected by high lead levels, including in the adjacent Townsville harbour.”