Lithium in drinking water may depress thyroid function.
Broberg, K, G Concha, K Engström, M Lindvall, M Grandér and M Vahter. 2011. Lithium in drinking water and thyroid function. Environmental Health Perspectives http://dx.doi.org/10.1289/ehp.1002678.
Lithium exposure from drinking water may lead to symptoms of underactive thyroid similar to the known side-effects of lithium treatment when it is used as an anti-depressant, finds a study of Argentinian women who live in the Andes Mountains.
The study is the first to examine the effects on thyroid hormone levels of broad, long-term lithium exposure through drinking ground water. The reported thyroid effects from exposure to near pharmaceutical levels suggest that drinking water should be more widely tested for lithium. The study is published in the journal Environmental Health Sciences.
Lithium is a naturally occurring metal used as a drug to treat symptoms of mania and depression that are associated with bi-polar disorder. It is especially helpful in people who are not responsive to other anti-depressant drugs. One known side effect of lithium use is underactive thyroid, which can lead to fatigue, weight gain and goiter. If an underactive thyroid is left untreated, it can result in more severe diseases, such as deafness and heart disease.
There are no drinking water standards for lithium set by any government. Several studies conducted in South America and one world-wide study of bottled water showed that it is possible to have several milligrams of lithium in a liter of water, leading to a daily exposure that is similar to what is given to treat depression.
The source of the lithium in the ground water analyzed in the study is not known. Researchers believe it may be associated with the region's thermal water. The particular study area in Argentina and neighboring areas in Chile have soil that is naturally rich in lithium, which dissolves into ground water. Food can also be a source of lithium.
In this study, researchers collected blood and urine from 202 women living in a village in the Andes Mountains of Argentina. High levels of lithium were discovered in the drinking water several years earlier. Researchers measured lithium and several other toxic metals in the women’s urine samples. Selenium and iodine – which come from food and are known to have beneficial effects on thyroid function – were also measured.
Two markers of thyroid function – thyroxine (T4) and thyroid stimulating hormone (TSH) – were measured in the women’s blood. Doctors frequently use low levels of T4 and high levels of TSH to diagnose underactive thyroid.
Women with higher lithium levels in the urine had lower levels of T4 and higher levels of TSH, though only a few women had levels that were outside of the range considered normal. The effects of lithium were similar even after exposure to other toxic metals was considered.
Lithium from drinking water is likely to have similar effects on thyroid function as lithium taken for depression, though it is unknown how common lithium exposure from drinking water is. On the other hand, selenium was associated with higher levels of T4, indicating that it might protect thyroid function.
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Based on a work at www.environmentalhealthnews.org.
