Some herbs used in traditional Chinese medicine contain pesticide residues up to 500 times above levels allowed by the European Union.

These findings were published in a report recently released by Greenpeace. It hired an independent lab to test samples of Chinese medicines from stores around the world, including Vancouver and Toronto.

Some of the residues found were from highly toxic pesticides that have been banned in China.

The samples were of some of the most widely-used herbs prescribed in traditional Chinese medicine (TCM). Samples of honeysuckle, often used to treat sore throats and colds, had over 100 times the EU recommended limit of the pesticide thiophanate-methyl. Samples of San qi, used to increase blood flow, had a cocktail of 39 different pesticide residues.

According to Dr. Michael Chung, a Vancouver-based traditional Chinese medicine practitioner, the risk of taking Chinese herbs is still unclear.

"We need more data before judging," says Chung.

Many TCM practitioners prescribe extracts of plants rather than raw herbs like those that Greenpeace tested. Chung says the extracts he uses have mostly been manufactured in Taiwan, which has more regulations in regards to pesticide residues.

Also, TCM herbs are usually used as tea and boiled. This could affect the potency of the pesticides, which are water-soluble.

Still, Chung is concerned about the increasing use of pesticides. "It's getting harder to find pesticide-free herbs," he says. Also, some of the herbs the Greenpeace report refers to, like chrysanthemums, are used raw as food.

Health Canada is responsible for the safety of natural health products, which include traditional Chinese medicines. In a written statement sent to The Tyee, Health Canada said that it's up to companies that sell the herbs to ensure they're within the limits set by the government.

If Health Canada gets a complaint or suspects contamination, they do test the contentious material. According to their databases, Health Canada hasn't detected pesticide residues in traditional Chinese medicines in the past eight years.

According to Greenpeace, long-term exposure to pesticides even at low levels can lead to learning and short-term memory problems as well as hormone disruption. The effects can be especially harmful for vulnerable populations like children.

Environmental effects of intense pesticide use in agriculture include loss of biodiversity, food contamination, and increased pesticide resistance. Also, farmers working with the pesticides can be at greater risk of poisoning.

The report is the second in a series by Greenpeace investigating increasing use of pesticides in agriculture in China. The first report, released last year, focused on residual pesticides found in Chinese teas.

As a result of the findings, Greenpeace is recommending that the Chinese government decrease the use of pesticides in agriculture and increase the training for and supervision of pesticide use.

Maryse Zeidler is completing a practicum at The Tyee.