As a result of their “down the drain” disposal, many personal care products end their lifecycle in aquatic ecosystems, where toxicity and biodegradability performance of ingredients is critically important to ensure environmental safety.
On of the key focus areas falling under the “environmental pillar” of Innospec’s sustainability and responsible business strategy is the commitment to supply safe and effective sustainable products which are designed to meet the needs of society and their customer base whilst minimizing their environmental impact.
Innospec’s mild, sulfate-free anionic isethionate and taurate surfactants are an ideal eco-friendly choice for skin and hair cleansing applications. These surfactants are readily biodegradable and not classified as environmentally hazardous to aquatic life in accordance with EU legislation on classification labelling and packaging (CLP). However, to qualify as raw material ingredients under the new EU Ecolabel criteria for cosmetic products and animal care products adopted into EU legislation as Commission Decision (EU) 2021/1870 in October 2022, all surfactants need to be biodegradable under both aerobic and anaerobic conditions.
Innospec has tested the biodegradation performance of its isethionate and taurate surfactants under both aerobic and anaerobic conditions, using a series of internationally standardised screening level tests. These tests range from OECD 301A-F (Ready Biodegradability under Aerobic Conditions) to OECD 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge).
In the former, the surfactants were incubated for 28 days in a mineral medium containing an inoculum of microorganisms. Degradation of the test substances over time was measured with using CO2 production (OECD 301B) or O2 uptake (OECD 301D) as an indicator of complete (ultimate) biodegradation to water, CO2 and nutrients. Positive control/reference substances are included in the test for validation and to prove the viability of the inoculum.
For the latter, washed and diluted digested sludge was incubated together with the individual surfactants in mineral test medium for 60 days in sealed vessels. The production of CO2 and CH4 as a measure of anaerobic degradation was determined by measuring the increase in headspace pressure in the test vessels and the proportion of the CO2 dissolved in the aqueous phase or transformed into carbonates was also measured.
The surfactants tested showed an “impressive performance” in both tests, the company said. All met the criteria for classification as readily biodegradable in accordance with the OECD 301 guidelines. SLMI was found to be anaerobically biodegradable in accordance with OECD 311 which also applies to SLI on the basis of read-across.
SMOT was clearly anaerobically biodegradable under the OECD 311 test conditions where it actually outperformed the positive control (sodium benzoate). As SMOT has a longer alkyl chain length than SMCT and SMLT, these are also considered anaerobically biodegradable based on read-across.
The results of the biodegradability testing in combination with the aquatic toxicity profile of these substances enables qualification of isethionate and taurate surfactants as ingoing raw materials for cosmetic products differentiated under recognized labelling and certification schemes for environmental excellence, such as EU Ecolabel, Nordic Swan and German Blue Angel.
