Detection of microbes, aflatoxin and toxic heavy metals in Chinese medicinal herbs commonly consumed in Thailand

Abstract

The increasing popularity of Chinese herbal treatment has sparked interest in investigating how safe these alternative medicines are. This study scrutinized the Chinese herbs used most popularly in Thailand to identify the presence of heavy metals, microorganisms and aflatoxin contamination. Five commonly consumed Chinese herbs were investigated: Milkvetch root (Astragalus membranaceus), Chinese angelica (Angelica sinensis), Goji berry (Lycium barbarum), Chinese yam (Dioscorea opposita) and Jujube (Ziziphus jujuba). Any heavy metal (arsenic, lead, cadmium), microorganisms (total viable count; total aerobic microbial count, total combined yeast and mold count), pathogenic bacteria (Staphylococcus aureus, Salmonella spp., Clostridium spp.) or aflatoxin contamination were examined. Of the 25 samples, sixteen (64.0%) did not exceed acceptable limits. Nor did the total aerobic microbial count, total combined yeast and mold count, aflatoxin and heavy metals exceed permissible limits. Neither Salmonella spp., nor S. aureus were found in any of the samples. However, significant Clostridium spp. contamination (36.0%) was detected in 9 of the 25 samples. These health hazards should be addressed systematically and for the long term by the appropriate consumer protection agencies and related organizations.