Confirming a long-suspected connection between smoking and infertility, scientists recently announced the results of a study finding that women who smoke cigarettes inhale a toxin that can destroy eggs in their ovaries and cause early menopause. The study was published in the journal Nature Genetics.
The toxins, Polycyclic Aromatic Hydrocarbons, also known as PAHs, were the focus of the study. Massachusetts General Hospital researchers discovered that PAH, found in cigarette smoke and air pollution, can accelerate the destruction of egg cells in ovaries, a normal function of menopause.
Girls are born with a finite supply of eggs that mature and are released during ovulation. Generally, women go through menopause in their late 40s or early 50s, but exposure to toxins such as PAH can trigger this process much earlier, according to the study.
Researchers injected female mice with PAHs and followed the chemical reactions within their bodies that caused their egg cells to die. A PAH attaches itself to the egg cell inside the uterus, which begins a chemical reaction causing the egg to die.
Scientists subsequently injected human ovary tissue under the mice's skin. The eggs began to die within three days of a PAH injection.
The study found that the eggs die in a slow and gradual process inside a woman's body. It may go on for years before being detected.
PAHs are released into the air during the burning of coal or other substances such as charbroiled meat. They can also be used to make tar, medicines, plastics and dyes.
The study's researchers call these toxins "silent killers" because they can destroy a whole group of cells before being discovered. Once they are discovered, it is too late to do anything, according to the scientists.
Scientists are now looking for ways to prevent egg destruction from chemical exposure. They are also looking into the possibility that women smoking during pregnancy could damage the ovaries of the female fetus, reducing the number of eggs she has in her body.