Researchers from the Hopkins Marine Station at Stanford University found that musk compounds inhibited natural defenses against toxicants in California mussels and that the effect remained long after exposure ended.
Humans are exposed to musks through the skin when they use soaps and cosmetics, and wear clothes washed with scented detergents. People also inhale musks through cologne sprays.
Under normal circumstances, cells resist toxicants through multidrug/multixenobiotic resistance (MDR/MXR) efflux transporters, proteins that keep foreign chemicals from entering cells. Using mussel gill tissue because its efflux transporters are particularly active, the researchers incubated tissue in a solution of musk compounds and a fluorescent dye. Finding the dye in the tissue would indicate that the efflux transporters were failing.
Immediately after exposure, the fluorescent dye uptake was 38-84% higher in tissue treated with musk compounds than in controls. Twenty-four hours later, dye uptake was still 30-74% higher in tissue exposed to musks.
"This study especially points to the need to screen musks and other environmental chemicals that accumulate in humans to determine if they are also chemosensitizers of MXR-related transporters. Especially critical will be to ascertain whether they cause long-term effects similar to those seen in our study,” the study authors write. "Effects on efflux systems could result in unanticipated accumulation of toxicants in humans and confound safety predictions of seemingly innocuous chemicals.”
Musk compounds are known to concentrate in fats, including breast milk, and endure in human tissue long after exposure. As a result, the researchers expressed concern that, even if ambient concentrations are low, long-term exposure could lead to accumulated tissue burdens high enough to inhibit natural cellular defenses in humans.
MEDICA.de; Source: Environmental Health Perspectives