A pilot study of occupational exposure to pathogenic microorganisms through lip cosmetics among dental hygienists

In dental clinics, dental hygienists are exposed to aerosolized pathologic bacteria, which can be transmitted to the oral cavity via lip cosmetics. Accordingly, such contamination poses a consistent health risk among staffs. Our study examined the bacterial contamination of lip cosmetics used by dental hygienists while in a clinic setting.

Sixteen dental hygienists were surveyed regarding their job assignments and habits associated with lip cosmetic. Subsequently, microorganisms were analyzed in collected samples of the hygienists' lip cosmetics using colony-forming unit (CFU) assays, 16s-rDNA polymerase chain reaction, and DNA sequencing.

Notably, 81.3% of the submitted lip cosmetic samples were contaminated, with bacterial CFUs ranging from undetectable to innumerable. Many samples (43.8%) exceeded the microbial limits of cosmetic contamination. Of the lip cosmetic used for more than 6 months, 60% exceeded the microbial limit. When wearing a mask every time, only one of the six samples exceeded the microbial limit. More frequent dental mask changing was associated with a lower likelihood that the cosmetic sample would exceed the microbial limit. No samples from hygienists who changed their masks four times a day exceeded the microbial limit, compared to 33.3% from hygienists who only changed the mask when it became wet. Most isolated bacteria were gram-positive, facultative anaerobic, asporogenic, and opportunistically pathogenic, and the most prevalent species were Staphylococcus aureus, Streptococcus salivarius, and Staphylococcus epidermidis.

Our findings indicate that dental staff, including dental hygienists, should exercise more careful workplace habits, particularly with regard to infection control and cosmetic use.