Heavy metal and pesticide content in commonly prescribed individual raw Chinese Herbal Medicines

Abstract

Heavy metal and pesticide contamination has previously been reported in Chinese Herbal Medicines (CHMs), in some cases at potentially toxic levels. This study was conducted to determine general patterns and toxicological significance of heavy metal and pesticide contamination in a broad sample of raw CHMs. Three-hundred-thirty-four samples representing 126 species of CHMs were collected throughout China and examined for arsenic, cadmium, chromium, lead, and mercury. Of the total, 294 samples representing 112 species were also tested for 162 pesticides. At least 1 metal was detected in all 334 samples (100%) and 115 samples (34%) had detectable levels of all metals. Forty-two different pesticides were detected in 108 samples (36.7%), with 1 to 9 pesticides per sample. Contaminant levels were compared to toxicological reference values in the context of different exposure scenarios. According to a likely scenario of CHM consumption, only 3 samples (1%) with heavy metals and 14 samples (5%) with pesticides were found with concentrations that could contribute to elevated background levels of contaminant exposure. According to the most conservative scenario of CHM consumption, 231 samples (69%) with heavy metals and 81 samples (28%) with pesticides had contaminants that could contribute to elevated levels of exposure. Wild collected plants had higher contaminant levels than cultivated samples. Cadmium, chromium, lead, and chlorpyrifos contamination showed weak correlations with geographic location. Based on our assumptions of the likely mode of consumption of raw CHMs, the vast majority (95%) of the 334 samples in this study contained levels of heavy metals or pesticides that would be of negligible concern. However, given the number of samples with detectable contaminants and the range between the more likely and more conservative scenarios of contaminant exposure, more research and monitoring of heavy metals (especially cadmium and chromium) and pesticide residues (especially chlorpyrifos) in raw CHMs are advised.

Adverse Events Associated with Metal Contamination of Traditional Chinese Medicines in Korea: A Clinical Review

“…Harris, et al27 collaborated with Chinese investigators to conduct federally funded research to analyze heavy metals and pesticides in commonly prescribed raw herbs from a wide range of geographical areas in China. In this study, 334 samples of raw herbs (representing 126 individual species) were collected and examined in duplicate for arsenic, cadmium, chromium, lead, and mercury.…”

Metals Content in Herbal Supplements

“…The presence of undeclared toxic metals in Asian products, especially natural products used in Indian Ayurveda medicine and of Chinese origin is widely reported [46][47][48]. Sahoo, Manchikanti, and Dey [49], pointed high frequency of the metals Fe, Pb, Hg, Cu, Cd, Zn, and As in Asian products.…”

A 68-year old woman with asymptomatic hypereosinophilia

“…This study found that pesticides were detectable in 36.7% of samples and at least one metal was found in all samples. 6 The poorly regulated nature of this industry makes it likely that alternative treatments could contribute to otherwise unexplained eosinophilia. A prior study had found that up to 70% of patients who use unconventional therapies did not inform their medical doctor, which reinforces the need to take a thorough history when evaluating patient eosinophilia.…”