[Determination of the benzo(a)pyrene content of 20 Chinese herbal drugs before and after charring].

The B(a)P [Benzo(a)pyrene] contents of 20 Chinese herbal drugs before and after charring were determined for the first time. The result shows that after charring the contents of 6 drugs tend to increase, accounting for only 30% of the total, while those of 14 drugs tend to decrease, making up 70%. This suggests that charred drugs are not carcinogenic if used properly. In the paper a discussion is also made of the factors and technological processes affecting the variation of B(a)P contents.