Less SO residue may not indicate higher quality, better efficacy and weaker toxicity of sulfur-fumigated herbs: Ginseng, a pilot study.

Sulfur dioxide (SO) is a hazardous residue in sulfur-fumigated herbs. Standards limiting SO content have been adopted worldwide for quality control of sulfur-fumigated herbs, and herbs with less SO are believed to be better. However, the standards are based only on the safe dose of SO and may not characterize changes in herbal quality, thereby the efficacy and toxicity, resulting from sulfur fumigation. To confirm this, here the correlation of residual SO content with the quality/efficacy/toxicity of sulfur-fumigated herb was investigated, and ginseng was selected as a pilot study object. Four sulfur-fumigated ginseng samples with different SO contents were systemically compared regarding their quality, anti-inflammatory, anti-shock and anti-stress efficacies, as well as acute and chronic toxicities. The results demonstrated that the SO content did not correlate with the quality, efficacy and toxicity changes of ginseng; more specifically, less SO residue did not indicate higher quality, better efficacy nor weaker toxicity. This fact suggests that SO content cannot characterize the variations in quality, efficacy and toxicity of sulfur-fumigated herbs. Therefore, the standard limiting SO content alone may be inadequate for quality control of sulfur-fumigated herbs, and new standards including other indicators that can exactly reflect herbal efficacy and safety are necessary.