Women with higher levels of triclosan, which has been previously linked to bowel cancer and antibiotic resistance, were more likely to have the bone disease, say researchers.
Triclosan is added to some toothpastes, antibacterial soaps and body washes, as well as some cosmetics. It can also be found in clothing, kitchenware, furniture and toys.
Manufacturers add it to reduce or prevent bacterial contamination and in toothpastes it helps prevent gingivitis.
The Food and Drug Administration (FDA) in the US has banned triclosan from antiseptic and antibacterial hand rubs and hand washes, but the UK has not issued a ban.
One manufacturer, Unilever, stopped adding triclosan to its products in response to consumer demand, but says it is confident the chemical poses no threat.
The new study analysed data from 1,848 women and found that those with higher levels of triclosan in their urine were more likely to have bone issues.
The author of the study, Yingjun Li, from Hangzhou Medical College School of Public Health in China, said: “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.
“As far as we know, this is the first epidemiological study to investigate the association between triclosan exposure with bone mineral density and osteoporosis in a nationally representative sample from US adult women.”
The study was published in Journal of Clinical Endocrinology and Metabolism.