Novel polylactic acid (PLA)-organoclay nanocomposite bio-packaging for the cosmetic industry; migration studies and in vitro assessment of the dermal toxicity of migration extracts

The exploitation of polylactide (PLA) nanocomposites (which integrate organically modified clays (organoclays) into polymers) in packaging for the cosmetics industry could provide a biodegradable alternative to the use of conventional plastics. In this study nanocomposites with a PLA polymer matrix and clay fillers organically modified with the quaternary ammonium salts, hexadecyl trimethyl ammonium bromide (HDTA) or octadecyl trimethyl ammonium chloride (TMSA), were produced and tested for their safe use in cosmetic packaging. To address concerns over the potential release of constituents from such nanocomposites, levels of total overall migration in a range of simulants (e.g. vegetable oil, aqueous media, and cosmetic formulations) was assessed 10 days post incubation at 40 °C following EU-Plastics Regulation 10/2011 concerning materials and articles in contact with foodstuffs. Total overall migration levels calculated for all PLA nanocomposites tested (maximum of 0.88 ± 0.44 mg/dm2) were well below the total established legislative migration limit (10 mg/dm2). Toxicity of the nanocomposite migration extracts to the skin was assessed in vitro. Exposure of skin cells (HaCaT immortalized human keratinocytes) and a full thickness epidermal skin model (EpiDerm™) to migration extracts did not result in any significant loss in cell viability or skin irritation (OECD TG 439). The results therefore indicate that the levels of migration from the nanocomposite measured was low, and that the nanocomposite migration extracts stimulated minimal toxicity to the skin. Up until now, the hazard of migration extracts from polymer-organoclay nanocomposites following dermal exposure has not been investigated and thus our study addresses a gap in knowledge. These findings can inform the safe design of bio-based biodegradable nanocomposite packaging (used by the cosmetics, and other industries) in the future to promote a more sustainable and greener economy for the plastics industry.