Author's reply

Sir,-We read with concem the correspondence from Hardell (1992; 49:743) who speculates on a causal relation between exposure to dioxin in hexachlorophene and the development of soft tissue sarcoma in a patient 17 years later. The author seems to be unaware of several considerations that would be relevant to the scientific establishment of a cause and effect relation in this case. Firstly, dioxin has not been shown to be carcinogenic in humans. Secondly, the daily dose of dioxin to which the patient may have been exposed was unknown, and based on the level alleged to be present in hexachlorophene, would be miniscule. The concept of dose-response, which is fundamental to medicine, has never been shown to be inappropriate for chemical carcinogenesis. Thirdly, other possible exposures (chemical or otherwise) before, con-