Pesticides in Herbal Medicines, the Insidious Public Health Hazard: Multi-Residue Pesticide Analysis and Risk Assessments Based on 1771 Samples

Background: Focus on the safety of herbal medicines has mainly been directed towards the presence of intrinsic toxicity, as found in the reported cases of renal and hepatic dysfunction caused by aristolochic acids. However, contamination from extrinsic hazards may have the potential to impart an even greater reduction in their safety and efficacy. Methods: Currently available herbal medicine samples from large-scale cultivation areas in major herbal medicines markets in China were collected for analysis of pesticides by LC/MS-MS or GC/MS-MS. Additionally, dietary exposure assessment, risk-ranking score and comparative health impact analysis were employed to estimate the hazard potential of pesticide residue exposure in herbal medicines. Findings: This study reveals that pesticides were present in the majority (88%) of a large, comprehensive cross-section (n=1771) of herbal medicine samples. Alarmingly, more than half (59%) contained pesticides over the European Pharmacopoeia (EP) limit, and 43% contained 35 varieties of banned, extremely toxic pesticides, eight of which were detected at levels over 500 times higher than the default Maximum Residue Limit (MRL). DDTs, carbofuran, and mevinphos were confirmed as being among the most risk-inducing pesticides by three different risk assessments methods, reported to produce carcinogenic, genotoxic, reproductive, and developmental effects, in addition to carrying nephrotoxicity and hepatotoxicity. Interpretation: Herbal medicines are severely contaminated with risk-inducing pesticides, therefore the authors strongly recommend the application of quality-control measures to safeguard public health. Funding Statement: This study was funded by the Study on the Key Safety Validation Elements of Chinese Medicine in International Trade, International Science & Technology Cooperation Program, PR China (2015DFM30030) and the OLCA-Pest Project, financially supported by ADEME, Denmark (17-03-C0025). Declaration of Interests: All authors declare no competing interests. Ethics Approval Statement: Not required.