Oil-based products are commonly used not only in industries but also in medical practice.1 Mineral oils are used in a wide range of cosmetic products like skin creams, lotions, cleansers, lip care products, etc., on account of their skin tolerance, and protecting properties as well as their high cleansing performance and broad viscosity options.2 Mineral oils and waxes are mixtures of saturated hydrocarbons consisting of straight-chain, branched and ring structures with carbon chain lengths primarily greater than C16, often referred to as ‘MOSH’ (mineral oil saturated hydrocarbons). The relative proportion of these structures determines the nature of the mineral oil or wax.2

It has been pointed that gaps exist in current understanding of the dermal penetration of mineral oils following long-term exposure to cosmetic products containing mineral oils and waxes.2

Experimental studies have shown the possible carcinogenic effects of aromatic hydrocarbons. The least dermatogenic effect has been shown by the hydrocarbons that contain 30.2% of aromatic carbon, while higher dermatogenic effect has been noted with samples that contain 35.2% of aromatic carbon. The highest dermatogenic effect has been shown by sample containing 55.2% of aromatic carbon.1

Available literature highlights that light mineral oils applied topically to the skin of experimental models led to marked epidermal hypertrophy, hyperplasia, hyperkeratosis, and subsequent depilation. N-Paraffin, isoparaffin, naphthene and aromatic fractions separated from light mineral oil each produced the dermatoxic effect as did highly purified individual paraffins from C12 to C18. Fractional distillation of the aromatic hydrocarbons from mineral oil representing the same distillation range could not yield fractions devoid of skin-damaging effects.3 Mineral oil has the potential to irritate the skin and cause rash or burning sensation.4

Mineral oil hydrocarbons are considered the greatest contaminant of the human body. A study sought to identify the sources of mineral oil contamination. The study enrolled 142 women undergoing elective cesarean section. A specimen of subcutaneous fat was obtained prior to wound closure. On days 4 and 20 postpartum, milk samples were collected from the women. Fat and milk samples were analyzed for mineral oil saturated hydrocarbons (MOSH). A questionnaire was also completed by the women on personal data, nutrition habits, and use of cosmetics. The major predictor for MOSH contamination of fat tissue was age. Body mass index, country of main residence, number of previous childbirths, use of sun creams in the present pregnancy, and use of hand creams and lipsticks in daily life were significant independent determinants. A strong correlation was seen between MOSH concentration in fat tissue (median 52.5 mg/kg) and in the corresponding milk fat sample from day 4 (median 30 mg/kg) and day 20 (median 10 mg/kg). Increase in MOSH concentration in human fat tissue with age points to an accumulation over time and cosmetics seem to be a relevant source of the contamination.5

A study evaluated the effects of topical virgin coconut oil (VCO) and mineral oil, on SCORAD (SCORing of Atopic Dermatitis) index values, TEWL, and skin capacitance in pediatric patients with mild to moderate atopic dermatitis (AD). Mean SCORAD indices reduced from baseline by 68.23% in the VCO group and by 38.13% in the mineral oil group. In the VCO group, 47% patients achieved moderate improvement and 46% showed an excellent response compared to 34% of patients showing moderate improvement and 19% showing excellent improvement in mineral oil group. The VCO group achieved a post-treatment mean transepidermal water loss (TEWL) of 7.09 from a baseline mean of 26.68, whereas the mineral oil group demonstrated baseline and post-treatment TEWL values of 24.12 and 13.55, respectively. In the VCO group, post-treatment skin capacitance increased to 42.3 from a baseline mean of 32.0, while in the mineral oil group, it increased to 37.49 from a baseline mean of 31.31. Topical application of VCO for eight weeks was found to be superior to that of mineral oil based on clinical (SCORAD) and instrumental (TEWL, skin capacitance) assessments.6

Considering the facts, it only seems wise to avoid using mineral oil-based products and switch to herbal oils for skin care.

References

1. Kimakova T, Poracova J, Dopirakova T, Blascakova M. Mineral Oils and Harmful Effects on Human and Animal Skin. Epidemiology 2011;22(1):S243.
2. Petry T, Bury D, Fautz R, et al. Review of data on the dermal penetration of mineral oils and waxes used in cosmetic applications. Toxicology Letters 2017;280:70-78.
3. Hoekstra WG, Phillips PH. Effects of topically applied mineral oil fractions on the skin of guinea-pigs. Available from: https://core.ac.uk/download/pdf/82433522.pdf.
4. Available from: https://www.nj.gov/health/eoh/rtkweb/documents/fs/1437.pdf.
5. Concin N, Hofstetter G, Plattner B, et al. Evidence for cosmetics as a source of mineral oil contamination in women. J Womens Health (Larchmt). 2011 Nov;20(11):1713-9.
6. Evangelista MTP, Abad-Casintahan F, Lopez-Villafuerte L. The effect of topical virgin coconut oil on SCORAD index, transepidermal water loss, and skin capacitance in mild to moderate pediatric atopic dermatitis: a randomized, double-blind, clinical trial. International Journal of Dermatology 2014;53:100–108.