SIOUX FALLS, S.D. -- It's likely your makeup bag is filled with far more than mascara, nail polish and lipstick.
A vast majority of makeup products are contaminated with bacteria such as E. coli, linked to fecal contamination, and Staphylococcus, according to researchers in the United Kingdom, in new research recently published in the Journal of Applied Microbiology.
Nine out of 10 in-use makeup products tested positive for bacteria, according to the research conducted by Dr. Amreen Bashir and Professor Peter Lambert of Aston University's School of Life and Health Sciences.
They examined the microbial contamination of five types of products: lipstick, lip gloss, eyeliners, mascaras and beauty blenders, and found a bacteria and fungi in all product types.
The products are contaminated because they're not kept clean and are used far past their expiration dates, according to the researchers.
Of particular note was the contamination found in beauty blenders, sponges used to apply skin foundation products. They were found to have the highest level of potentially harmful bacteria, with 93 percent never having been cleaned despite more than two-thirds of the products being dropped on the floor during use.
The research is the first to look at beauty blender products, which can be particularly susceptible to contamination since they're often left damp after use, prime breeding ground for bacteria, the researchers said.
"Consumers' poor hygiene practices when it comes to using makeup, especially beauty blenders, is very worrying when you consider that we found bacteria such as E. coli -- which is linked with fecal contamination -- breeding on the products we tested," said Bashir. "More needs to be done to help educate consumers and the makeup industry as a whole about the need to wash beauty blenders regularly and dry them thoroughly, as well as the risks of using make-up beyond its expiry date."
Contact with contaminated products could cause illnesses ranging from skin infections to blood poisoning, but could prove particularly serious for people with compromised immune systems.
The researchers said their work shows consumers unwittingly put themselves and risk and manufacturers and regulatory bodies should do more to put prominent expiration dates and cleaning instructions on the packaging of makeup products. In the U.S., there are no regulations that require makeup packaging include the products' expiration dates.