Study Links Cadmium Levels in Women’s Urine to Endometriosis

Women with a history of endometriosis have higher levels of cadmium in their urine than women without this diagnosis. This is according to a study by Michigan State University, which suggests that the toxic metal may be linked to the development of endometriosis.

Endometriosis is Still Under-Researched

Endometriosis is a gynecological disorder that affects one in 10 women of reproductive age and in which tissue that looks like the lining of the uterus also appears outside the uterus and spreads to other organs. Endometriosis patients often suffer from chronic, painful and debilitating symptoms that can affect all aspects of life, including daily activities, job productivity, school performance and personal relationships.

Despite the detrimental effects of endometriosis on quality of life, the disease has not yet been adequately researched. By examining environmental risk factors such as the metal cadmium, researchers led by Kristen Upson, assistant professor in the Department of Epidemiology and Biostatistics at the MSU College of Human Medicine and lead author of the study, are getting closer to understanding the risk factors for this condition.

The Absorption of Cadmium by The Body

Cadmium is a toxic metal and a “metal estrogen”, which means that it can act like the hormone estrogen. This substance has been accumulating in the soil for centuries. Unfortunately, certain foods such as seafood, offal, wild mushrooms, wheat, leafy vegetables and potatoes are also highly contaminated with cadmium, and the European Food Safety Authority(EFSA) has set the tolerable level at 2.5µg per kilogram of body weight per week to avoid developing health problems. Smokers have a higher cadmium intake, as 50% of the cadmium contained in tobacco is absorbed by humans.

While this is not the first study to investigate a possible link between cadmium and endometriosis, the researchers say it is the largest study to measure cadmium in urine, reflecting long-term exposure between 10 and 30 years.

A 60% Increased Prevalence of Endometriosis

For their study, the researchers used data from the National Health and Nutrition Examination Survey (NHANES), a national study representative of the US population between 1999 and 2006. Of the more than 41,000 participants in the survey, the researchers limited their study population to 20- to 54-year-olds with endometriosis diagnosis information. The researchers then analyzed the data and divided the cadmium levels into four classes or quartiles, with the first quartile representing the lowest exposure and the fourth quartile representing the highest exposure. They found that participants in the second and third quartiles were twice as likely to be diagnosed with endometriosis as those in the first quartile. The data also indicated a 60% increased prevalence of endometriosis when looking at urinary cadmium concentrations in the fourth quartile.

The results are interesting when you consider that cadmium can act like the hormone estrogen, and this hormone plays a central role in the development of endometriosis. The researchers say that further studies are needed to confirm their findings. According to Upson, this work is part of her broader research looking at everyday factors that can increase women’s exposure to toxic metals, as well as the effects of toxic metals on gynecological health.