BODY CARE
69
Second-generation water- based insect repellents
Laurence Hooley – Chemian Technology
Consumer demand for natural, plant-based alternatives to synthetic mosquito repellents like DEET (N,N-diethyl-meta-toluamide) has been building for some years. This is driven, in part, by increased consumer awareness of certain negative issues related to the use of DEET and the wider preference for effective, safe-to-use personal care products that are based on raw materials from renewable and sustainable resources. Ecocert and COSMOS natural certification -
long-established and important standards in the cosmetic industry - are now finding increasing relevance in the market for insect repellents and the active ingredients they contain. Uniquely and unlike materials used in the
cosmetic industry, the natural claims made for active ingredients in mosquito repellents remain secondary in importance to their efficacy - for obvious reasons concerning the potential implications for their role in the prevention of dangerous insect vector-borne diseases like malaria, dengue and Zika virus. Natural, plant-based extracts that make notional, unquantified or unsubstantiated claims around repellence are a poor and ineffective substitute for proven and trusted synthetic actives.
A watershed moment In European markets, the implementation of ECHA’s Biocidal Product Regulation (BPR) represents a watershed for natural offerings due to the Regulation’s compulsory requirement for repellent active manufacturers to provide proof of efficacy according to prescribed, standardised test methodology. Product claims around efficacy and the
quantification of protection, measured in hours, must now be supported by actual data. Prior to this, under the preceding European Biocide Directive (98/8/EC) controlling repellent actives, this had not been the case. The raising of the technical bar to market
entry has narrowed the options available to formulators and para menthane 3,8-diol (PMD)-based actives have emerged as the principle material offering equivalent efficacy to that of established synthetic actives. First generation PMD-rich botanical oils
(PMDRBO) derived from Eucalyptus citriodora (EC) essential oil feedstocks, provided the basis for the first truly Natural, PMD-based repellents and these are now widely available
www.personalcaremagazine.com
Figure 1: The acid catalysed hydration of Citronellal
in the market - offered by natural product specialists and available within the portfolio of major consumer goods brand platforms, (repellent) market specialists and retailer brands.
These EC oil-based active ingredients have
traditionally been formulated as alcoholic solutions for application by aerosol or pump spray.
Second generation PMDRBO The growing trend for pleasant, safe-to-
use and more cost-effective, water-based formulations has led to the development of a second generation PMDRBO, Citrepel® 75, based on a fractionated Cymbopogon winterianus (Java Citronella) essential oil, which can, uniquely, be formulated with cold process to deliver stable o/w emulsions for lotions, sprays, creams, roll on, wipes and solid stick formulations (warm process), without the need for
alcohol or co-solvents (Table 3). PMD, as the major constituent and
functional molecular component of PMDRBO,
is formed by the acid catalysed hydrolysis of a double bond within Citronellal – the main aldehyde component of the fractionated feedstock oil - with simultaneous ring closure (Prins reaction), producing a mixture of isomers – all of which have repellent activity.
Efficacy testing for mosquito repellents Validated efficacy testing for mosquito repellents is carried out using arm in cage methodology, performed on a pre-qualified sample group (test subjects are selected according detailed fitness criteria and must demonstrate attraction to the mosquito species population used in the test). The test measures the efficacy of the
repellent by recording the number of bites to an exposed area of the treated arm during a 60-second exposure within the mosquito
October 2024 PERSONAL CARE
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