Interactions Between Skincare Product Ingredients and the Skin Microbiome

Skin serves as a critical barrier between our bodies and the environment and the locus for a diverse and active microbial community. The composition and metabolic activity of the microbial community on the skin is presumably influenced by the local chemical environment, which includes natural skin lipids (e.g., squalene and sapienic acid), components of personal care products applied directly to skin, and semi-volatile organic compounds (SVOCs) that reach the skin through gas phase absorption, dust deposition, and direct contact with surfaces. Common semi-volatile ingredients in skin care products include phthalates, parabens, and UV blocking compounds (e.g., oxybenzone, octocrylene or homosalate).

The investigators have recently demonstrated a method of collecting chemicals from areas of skin with infrequent direct dermal contact using alcohol wipes to assess passive air to skin partitioning of both target and nontarget compounds (Garrido et al., in review). Low-volatility reaction products can accumulate in skin oils and act as skin irritants, with the potential of being absorbed into the bloodstream. With methods developed for chemical and microbiome sampling, the overall goal of the proposed research is to develop an understanding of the two-way interaction between organic chemicals on the skin and the composition of the skin microbiome.

Inclusion criteria

• Individuals aged 15 and over
• No known medical conditions that, in the investigator's opinion, may interfere with study participation.

Exclusion criteria

• Individuals who have been on any medication (including antibiotics, probiotics, prebiotics) that has caused a change in current skin composition of interest based on the opinion of the investigator.
• Individuals with systemic antibiotic use within last 60 days.
• Individuals with topical antibiotic use on the test sites within last 30 days
• Individuals unwilling/unable to avoid topical antibiotics, systemic antibiotics, prebiotics, and probiotics during study.
• No other interfering skin products should be used during duration of study. (Paraben-free & phthalate-free personal product "safe" list will be provided for other uses during study period if needed).
• Individuals unwilling or unable to undergo 1 week wash-in with paraben/phthalate-free products if needed in the opinion of the investigator.
• Female volunteers who are pregnant or are actively breastfeeding or planning a pregnancy within two months. (There is no known concern for risk to fetus but pregnancy can alter the microbiome being studied)
• Female volunteers who have started a new hormonal birth control agent or switched to a hormonal birth control agent within the past 60 days
• Individuals using any interfering skin products in the opinion of the investigator within 2 weeks of enrollment into the study.
• Individuals who have participated in any other clinical studies using the same test sites (face) in the past 14 days
• Individuals with a known history of hypersensitivity to any ingredients to the cosmetic agent that is being assessed
• Individuals who have history of a psychological illness or condition that would interfere with their ability to understand and follow the requirements of the study at the discretion of the investigator.