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Mercury and Cadmium Pose Risk to IVF Pregnancy

by Leigh Ann Woodruff, July 26, 2012

While it's common sense to reduce exposure to environmental toxins when trying to conceive, a new study from the University at Albany's School of Public Health published in Reproductive Toxicology finds that low levels of the toxic metals mercury and cadmium could be significantly harmful to women pregnant via in vitro fertilization (IVF).

"We routinely counsel our patients about toxic exposures during the IVF and pregnancy process," says Julie Tan, M.D., a fertility doctor with the Cleveland Clinic Fertility Center. "However, this preliminary study is interesting because it highlights the possible negative impact of low-level 'background' exposure in an IVF population."

The researchers adjusted for factors such as age, race and smoking, and they found that a slight increase of 1 microgram per liter (ug/L) of blood mercury is associated with a diminished likelihood of 35 percent of achieving a clinical pregnancy with IVF. Cadmium had an even larger impact — a 1 ug/L blood increase of cadmium reduced pregnancy success by 94 percent in clinical pregnancies. Clinical pregnancies are pregnancies that have the presence of a gestational sac detected by ultrasound.

"This preliminary study suggests that environmental exposures to toxic metals may negatively impact the chances for conceiving from in vitro fertilization, but further study is needed to validate these concerns," says Victor Y. Fujimoto, M.D., a reproductive endocrinologist with University of California, San Francisco, Center for Reproductive Health, and one of the lead authors of the study.

Mercury and cadmium do occur naturally in the earth's environment, but under certain conditions, they accumulate and become concentrated.

Too much mercury can affect brain development and the nervous system. It is often found in fish, and pregnant women and those trying to conceive are warned about consuming too much. The Food and Drug Administration (FDA) has guidelines for children, pregnant women and those trying to conceive recommending that no more than 12 oz of low mercury fish should be consumed weekly. For reference, tuna is a high mercury fish, while flounder is low mercury. Mercury sources include:

  • emissions from coal-burning power plants
  • plants
  • fish
  • shellfish
  • herbal treatments

Cadmium is another contaminant that is found in the air from the burning of fossil fuels, in food due to phosphate fertilizers or sewage sludge and from cigarettes. Smokers have about twice as much cadmium in their bodies as non-smokers. Sources of cadmium include:

  • cigarette smoke
  • phosphate based fertilizers and sewage sludge
  • plants grown in cadmium-adulterated soil
  • organ meats such as liver and kidneys
  • mollusks
  • fossil fuel combustion emissions
  • discharge from steel and iron production plants

"The lifestyle factors that contribute to infertility and the success or failure of in vitro fertilization remain relatively obscure," says Dr. Fujimoto. "Studies such as ours will broaden our understanding so that modifiable environmental factors of IVF success are identified, and the information is disseminated to the public." With further studies, clear guidelines may be developed for the impact of these toxins on IVF.

In the meantime, fertility doctors recommend reducing exposure as much as you can.

"I will continue to recommend avoiding these substances when possible, including reducing smoking and work-related contact with metals such as mercury, lead, and cadmium in women who are trying to conceive, including those who are undergoing the IVF process," says Dr. Tan. "However, additional studies with larger numbers of patients are needed before widely applying the findings from this report."

Says Dr. Fujimoto, "Women should be aware of their dietary exposures to various environmental toxins and make effort to minimize exposures through reducing cigarette smoke exposure, as well as the avoidance of prepackaged processed foods and seafood containing high levels of toxic metals."


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