A recent study finds a relationship between a chemical that is in a wide array of personal care products and a reduction in bone mineral density.

Osteoporosis is a disease that causes weak bones and an increased risk of fracture. Worldwide, an estimated 200 million people currently have osteoporosis. More than 10 million of these people live in the United States. Osteoporosis predominantly affects people as they age, so as the population of the United States is growing older, the condition is likely to become more prevalent over time.

Although there are several causative factors, including genetics, certain medications, and body mass index (BMI), some researchers are interested in the potential role of environmental chemicals. A new study, the findings of which appear in the Journal of Clinical Endocrinology & Metabolism, investigates a chemical called triclosan.

What is triclosan?

Triclosan is an antibacterial compound. The Food and Drug Administration (FDA) recently banned its use in over the counter hand sanitizers, but manufacturers still add it to a range of goods, including toothpaste, soap, and mouthwash. They also add it to some textiles and kitchenware. As an insight into how prevalent this chemical is, in one US study, scientists detected triclosan in the urine of almost three-quarters of their 2,517 participants.

The corresponding author of the new study, Yingjun Li, PhD, from Hangzhou Medical College School of Public Health in China, explains why the team chose to investigate triclosan's role in osteoporosis, "Laboratory studies have demonstrated that triclosan may have potential to adversely affect the bone mineral density in cell lines or in animals. However, little is known about the relationship between triclosan and human bone health."

Doctors use bone mineral density tests to diagnose osteoporosis and determine fracture risk. Li believes that their research is the first to "investigate the association between triclosan exposure with bone mineral density and osteoporosis in a nationally representative sample from US adult women."

Bone data

Li and colleagues took data from the National Health and Nutrition Examination Survey, which the researchers had collected during face to face interviews. The questions covered demographics, diet, and general health. Medical professionals also gave each participant physical examinations and took blood and urine samples.

In the new study, the researchers analyzed data from 1,848 women aged 20 years or older who were living in the United States. The researchers tested for triclosan in the urine samples, measured bone mineral density, and assessed the participants for osteoporosis.

During the analysis, the team controlled for a number of variables that had the potential to skew the results, including age, ethnicity, level of physical activity, smoking, calcium intake, BMI, and history of diabetes.

Overall, the analysis showed that women with higher levels of urinary triclosan had reduced bone mineral density in comparison with women with lower levels of urinary triclosan. This relationship was more pronounced in postmenopausal women and was not significant in premenopausal women.

Triclosan and osteoporosis

When the scientists investigated the relationship between triclosan and osteoporosis, the results were less clear. This finding may partly be due to the number of individuals with osteoporosis being relatively low—only seven women in the premenopausal group, for instance.

The researchers evaluated four bone regions for the presence of osteoporosis. For three of the four regions, there was no relationship between triclosan and osteoporosis. However, higher levels of triclosan did predict an increase in osteoporosis in the intertrochanter region, which is the upper part of the thigh bone.

Although the links between triclosan and osteoporosis were not as strong as the authors had expected, the chemical does appear to affect bone density in some way. However, the authors note certain limitations. First and foremost, the study design does not allow the authors to prove cause and effect. They also explain that the excretion of triclosan is quite rapid. Therefore, because they only measured urinary triclosan once, it is probably not a fair representation of average triclosan levels throughout the decades. As is always the case, scientists will need to carry out much more research using a larger group of participants to confirm these findings.