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

Eric S.J. Harris, Shugeng Cao, Bruce A. Littlefield, Jane A. Craycroft, Robert Scholten, Ted Kaptchuk, Yanling Fu, Wenquan Wang, Yong Liu, Hubiao Chen, Zhongzhen Zhao, Jon Clardy, Alan D. Woolf, David M. Eisenberg

Research output: Contribution to journalArticlepeer-review

149 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)4297-4305
Number of pages9
JournalScience of the Total Environment
Issue number20
StatePublished - Sep 15 2011
Externally publishedYes

Bibliographical note

Funding Information:
This work was supported by grants from the National Institutes of Health National Cancer Institute ( U19 CA128534 ), the National Center for Complementary and Alternative Medicine ( AT03002 “PIRC” ), and the Bernard Osher Foundation . The sponsors were not involved in the collection, analysis, or interpretation of the data; in writing the report; or the decision to submit the paper for publication. Dr. Kaptchuk was partially supported by a grant from the National Institutes of Health ( K24 AT004095 ). Dr. Woolf was supported (in part) by the Region 1 Pediatric Environmental Health Specialty Unit (PEHSU) under a cooperative agreement award number 1U61TS000118-01 from the Agency for Toxic Substances and Disease Registry (ATSDR). The U.S. Environmental Protection Agency (EPA) supports the PEHSU by providing funds to ATSDR under Inter-Agency Agreement number DW-75-92301301-0 . Neither EPA nor ATSDR endorse the purchase of any commercial products or services mentioned in PEHSU publications. We acknowledge guidance provided on dietary exposure assessment and risk assessment methodologies from David J. Miller, Bernard Schneider, Aaron Niman, and David Hrdy of U.S EPA's Office of Pesticide Programs. We acknowledge NSF International Center for Applied Research, Ann Arbor, Michigan for performing the chemical analyses and for help with the toxicological assessment. Additionally, the authors would like to acknowledge comments from Drs Roger Davis (Harvard Medical School), Sumeeta Srinivasan (Harvard University Center for Geographic Analysis), and P. Michael Bolger (FDA, Chemical Hazards Assessment Team) on earlier drafts of the manuscript.


  • Exposure assessment
  • Heavy metals
  • Herbal products
  • Pesticide residues
  • Traditional chinese medicine (TCM)


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