High exposure to triclosan, an antibacterial agent commonly found in consumer products, is associated with low bone mineral density (BMD) and an increased risk of osteoporosis among women, suggests epidemiological data from the NHANES*.

“Triclosan is an antimicrobial used in varieties of consumer goods and personal care products including soaps, hand sanitizers, toothpaste, and mouthwash,” the researchers explained.

“Triclosan is characterized as [an] endocrine disruptor chemical in multiple species, including humans,” they added. “Environmental exposure of triclosan usually comes from triclosan-containing consumer products or triclosan-contaminated water and/or animal/food products.”

The study included 1,848 women aged ≥20 years (mean age 47.7 years) who participated in the NHANES between 2005 to 2010 in the US. They were assessed on BMD using DEXA** scans and urinary triclosan levels using HPLC***-tandem mass spectrometry of spot urine samples collected. [J Clin Endocrinol Metab 2019;doi:10.1210/jc.2019-00576]

Compared with women in the lowest tertile of urinary triclosan concentration, those in the highest tertile were significantly more likely to show a lower BMD at the lumbar spine (β=–0.014, 95 percent CI, -0.029 to 0.001), total femur (β=–0.016, 95 percent confidence interval [CI], -0.032 to -0.000), and intertrochanter (β=–0.022, 95 percent CI, -0.042 to -0.002), after adjusting for multiple variables such as age, race, physical activity, body mass index, diabetes, calcium intake, hormone use, smoking, menopause, and marital status.

When the analysis was stratified by menopausal status, the inverse association between urinary triclosan levels and BMD became more pronounced among postmenopausal women, but was attenuated among premenopausal women.

Also, women in the highest urinary triclosan tertile had more than twofold risk of having osteoporosis in the intertrochanter compared with those in the lowest tertile (odds ratio, 2.46, 95 percent CI, 1.190–5.105). No such associations were seen in other regions measured.   

“We speculate that the disruption in thyroid axis caused by exogenous compounds such as triclosan could lead to lower BMD and increased prevalence of osteoporosis in the US adult women … [as] thyroid hormone signalling is important for normal skeletal development and adult bone maintenance,” suggested the researchers.

Another potential mechanism behind the association may be attributed to triclosan’s anti-oestrogenic activity, as shown in in vitro studies of human cells, they pointed out.

As this is an observational study with cross-sectional design, the researchers cautioned against extrapolating the association to establish a causal relation between triclosan and osteoporosis.

Thusfar, the US FDA has banned the use of triclosan in consumer antiseptic hand washes, consumer hand sanitizers, and healthcare antiseptics.

However, as triclosan can be found in many consumer products, including clothing, kitchenware, and toys, “people’s long-term exposure to triclosan is higher than previously thought, raising concerns about the potential risks associated with the use of this ingredient over a lifetime,” according to a recent FDA consumer update.