Cyndi: "Grow your own herbs and use them in your for foods, as they are important for health."

MANY herbal medicines are contaminated with potentially lethal doses of heavy metals such as arsenic and mercury, belying their reputation as low-risk "natural" products.

Cheaper and less effective herbs may be substituted for the one on the label, and some medicines are often secretly adulterated with conventional prescription or over-the-counter drugs to boost their effectiveness.

The warnings come from an Australian expert, who conducted a review of the potential hazards linked to herbal medicines -- and came away shocked by how many different dangers there were.

A previous analysis of 251 herbal products sold in the US found arsenic in 36, mercury in 35 and lead in 24 of the preparations, according to the review by Roger Byard, a forensic pathologist at the University of Adelaide.

One report of lead poisoning that Professor Byard turned up in his research involved a five-year-old boy, who was treated with "Tibetan herbal vitamins" and ingested an estimated 63 grams of lead over four years, the equivalent of 430 times the recommended maximum allowance.

Another five-year-old boy with retinal cancer in both eyes developed arsenic poisoning after his parents gave him a traditional Indian remedy.

The paper, published in the US-based Journal of Forensic Sciences, said the presence of harmful substances might be accidental or deliberate, but in both cases it posed dangers to patients through interactions with their existing treatments.

"There's a false perception that herbal remedies are safer than manufactured medicines, when in fact many contain potentially lethal concentrations of arsenic, mercury and lead," Professor Byard said. "These substances may cause serious illnesses, exacerbate pre-existing health problems or result in death, particularly if taken in excess or injected rather than ingested."

Marc Cohen, professor of complementary medicine at RMIT, backed the call for patients to tell their doctors about their herbal treatments, but rejected Professor Byard's warnings as "alarmist".

"If you looked at the number of food poisoning cases, and the number of toxins in food, you wouldn't go near it," Professor Cohen said. "Everyone needs to be careful with anything they put in their mouth . . . Herbal medicines are safe, and are relatively well-regulated in Australia."

Source: Adam Cresswell, The Australian, February 9 2010, http://www.theaustralian.com.au/news/nation/herbal-cures-a-toxic-mix/story-e6frg6nf-1225828052335

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