A popular misconception (at least in health-conscious Southern California) is that natural substances are in general safer than artificial ones. Some people who would never take a prescription medication without educating themselves about the possible side effects use natural products without a second thought.
Last week’s New England Journal of Medicine published an article which is a startling example of natural products having potent and harmful health effects. The article reports the case studies of three healthy prepubescent boys who developed breast tissue enlargement (gynecomastia). Blood testing showed that their endogenous hormone levels were normal for prepubescent boys, meaning their bodies were not making excess estrogen which would cause the gynecomastia.
Detailed questioning revealed that all three boys were using topical products containing lavender oil or lavender and tea tree oil. One boy’s mother was regularly applying a balm containing lavender oil on his skin. The second boy was using a hair styling gel and a shampoo both of which contained lavender oil and tea tree oil. The third boy was using lavender-scented soap and lavender-scented skin lotions. All three boys’ gynecomastia resolved after discontinuation of these products. Testing in the laboratory of lavender oil and tea tree oil on human breast tissue showed that these oils have estrogen-like effects.
Is there a larger lesson here other than that we should avoid lavender oil and tea tree oil? Only that we should not assume anything about a substance’s safety from the fact that it’s natural. Both humans and nature have produced biologically potent dangerous chemicals. The only way to distinguish them from safe chemicals is to study their effects.