Recent research published in the July issue of the journal Environmental Health Perspectives, demonstrates a non-monotonic dose-response relationship between serum TCDD levels and age of onset of natural menopause.
The age of onset of menopause is believed to reflect the rate of atrophy of the ovarian follicles. Alterations in age at menopause can have important health implications because women with early menopause are at higher risk for osteoporosis, cardiovascular disease, and reproductive cancers.
2,3,7,8-Tetrachlorobenzo-p-dioxin (TCDD), a halogenated compound that binds the aryl hydrocarbon receptor, is a by-product of numerous industrial processes including waste incineration. Dioxin, a known human carcinogen, is also thought to disturb the reproductive and endocrine systems.
The authors examined the relationship of TCDD and age of onset of natural menopause in a population of women residing near Seveso, Italy, in 1976, at the time of a chemical plant explosion. These women were exposed to the highest levels of TCDD known in residential populations.
The study included 616 of the women who participated 20 years later in the Seveso Women¡¯s Health Study (SWHS). All women were pre-menopausal at the time of the explosion, had TCDD levels measured in serum collected soon after the explosion, and were ¡Ý 35 years of age at interview.
Using proportional hazards modeling, the researchers found a 6% non-significant increase in risk of early menopause with a 10-fold increase in serum TCDD. The results suggest a nonmonotonic dose-related association with increasing risk of earlier menopause up to about 100 ppt TCDD, but not above.
The women in this study experienced substantial TCDD exposure during the post-pubertal¨Cadult developmental period. The authors suggest continued follow-up of the younger women in the SWHS cohort as well as the female offspring of the SWHS cohort.