Researchers at the University of California, Berkeley's School of Public Health detected lead, cadmium, chromium, aluminum and five other metals in lipsticks, some of which were found at levels that could raise potential health concerns.
They tested 32 different lipsticks and lip glosses commonly found in drugstores and department stores.
Prior studies also have found metals in cosmetics, but the UC Berkeley researchers estimated risk by analyzing the concentration of the metals detected and consumers' potential daily intake of the metals, and then comparing this intake with existing health guidelines.
"Just finding these metals isn't the issue; it's the levels that matter," study principal investigator S. Katharine Hammond, professor of environmental health sciences said.
"Some of the toxic metals are occurring at levels that could possibly have an effect in the long term," Hammond said.
Lipstick and lip gloss are of special concern because when they are not being blotted on tissue or left as kiss marks, they are ingested or absorbed, bit by bit, by the individual wearing them, the study authors said.
The researchers developed definitions for average and high use of lip makeup based on usage data reported in a previous study.
Average use was defined as a daily ingestion of 24 milligrams of lip makeup per day.
Those who slather on the lip color and reapply it repeatedly could fall into the high use category of 87 milligrams ingested per day.
Using acceptable daily intakes derived from this study, average use of some lipsticks and lip glosses would result in excessive exposure to chromium, a carcinogen linked to stomach tumors.
High use of these makeup products could result in potential overexposure to aluminum, cadmium and manganese as well.
Over time, exposure to high concentrations of manganese has been linked to toxicity in the nervous system.
Lead was detected in 24 products, but at a concentration that was generally lower than the acceptable daily intake level.
However, the lead levels still raised concerns for young children, who sometimes play with makeup, since no level of lead exposure is considered safe for them, the researchers said.
The findings are set to be published online in the journal Environmental Health Perspectives.