Thanks Hip. I did take a look and it wasn't very satisfying, except that they ended up with what researchers often say: We need more research into this question. I certainly agree with that.
What they didn't include in their conclusion but was in the body of the article:
"According to the more conservative method, the percent of samples with the potential for contributing to elevated background levels of each metal were:
34% for arsenic;
52% for cadmium;
53% for chromium;
12% for lead, and 1% for mercury."
and
"Eighty-one samples
(27.5%) had levels of pesticides that could contribute to an elevated background exposure in the more conservative assessment."
The study wasn't very rigorous in that they made a lot of assumptions, which they acknowledged, but which if in error, would completely invalidate their conclusions. Unfortunately, they don't say which herbs they examined.
Re: Dr. Chia's statement in the video, I had the impression he was telling why the average patient can't be expected to do this kind of research herself before taking an herb. And the fact he, himself, hasn't done it does not lead to a conclusion that no one has, in my personal logic. Another thread here on PR mentions that he started producing Equilibrant because of "concerns" about oxymatrine being contaminated and that he had found a dependable source out of Hong Kong. I get the impression that he isn't searching for a negative (contamination) but rather a (positive), a source that tests their product and certifies it to be clean.
The statement from his office also said persons with autoimmune disease should not take oxymatrine. I tend to think my me/cfs is neuroimmune, not autoimmune, but who knows at this point.
I have used google scholar and the Chinese database on TCM (
http://search.cnki.com.cn) and have not found any studies looking for contamination. But, when I searched for that, most of the article were in Chinese so I don't know what they said.
Interestingly, oxymatrine is called a "biopesticide" in some of the articles and found to be toxic for honeybees.
And, on the subject of contamination, herbal remedies from anywhere can be contaminated. Steven Bruhner cautions about collecting certain herbs near highways or industrial sites. And the article you cited mentions that wildcrafted herbs had higher levels of contamination than commerically grown ones. They speculated that that is because those herbs' past crops had already taken up the contaminants, in effect cleaning the soil, and the present and subsequent crops were cleaner.