Well-known traditional Chinese medicine (TCM) giant Beijing Tongrentang Co attracted quite a bit of bad press recently when authorities in Hong Kong announced that excessive amounts of mercury, a toxic heavy metal, were found in three of its products.

Such stories are nothing new for the TCM industry. The main issue here is that raw materials and ingredients used in TCM products are frequently grown or collected in rural villages where the ground water and the soil is contaminated with heavy metals running off from nearby factories. Of course, it doesn't help that quality and safety watchdogs often lack the resources, the technology or the expertise to detect toxic products.

To keep heavy metals and other poisons out of TCMs, manufacturers should be encouraged to produce their own raw materials. They have to work out their own soil and water quality standards if official guidelines are too vague or enforced too sparingly.

The author is Wang Yuejin, an economic commentator.