Less SO₂ residue may not indicate higher quality, better efficacy and weaker toxicity of sulfur-fumigated herbs: Ginseng, a pilot study

Sulfur dioxide (SO₂) is a hazardous residue in sulfur-fumigated herbs. Standards limiting SO₂ content have been adopted worldwide for quality control of sulfur-fumigated herbs, and herbs with less SO₂ are believed to be better. However, the standards are based only on the safe dose of SO₂ 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 SO₂ 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 SO₂ 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 SO₂ content did not correlate with the quality, efficacy and toxicity changes of ginseng; more specifically, less SO₂ residue did not indicate higher quality, better efficacy nor weaker toxicity. This fact suggests that SO₂ content cannot characterize the variations in quality, efficacy and toxicity of sulfur-fumigated herbs. Therefore, the standard limiting SO₂ 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.