Dioxins

3. What are the effects of dioxins in laboratory animals?

• 3.1 What are the non-cancer effects on animals?
• 3.2 Do dioxins cause cancer in laboratory animals?

3.1 What are the non-cancer effects on animals?

Toxic dioxins, especially 2,3,7,8-TCDD, can cause multiple non-cancer effects in animals at varying doses. Direct effects can be toxic or not. Non-toxic effects observed at low dose may or may not result subsequently in toxic effects in the animal or its offspring.

Some of the toxic effects observed at lower exposures are endometriosis (uterine disease), neurobehavioral (cognitive) effects, reduced sperm counts, female urogenital malformations and effects on the immune system.

Dioxin levels in the general population of industrialized countries sometimes reach the lower levels at which significant effects have been observed in animals. More...

3.2 Do dioxins cause cancer in laboratory animals?

2,3,7,8-TCDD has been shown to be carcinogenic to multiple animal species of both sexes. Most dioxins do not initiate cancer as such, but indirectly promote growth and proliferation of previously initiated cancerous lesions.

The cancer observed at the lowest exposure are liver tumors in rats. 2,3,7,8-TCDD also caused thyroid tumors in male rats.

Several other dioxin types have also been shown to be cancer promoters. More...