*Eigenmann & Veronelli is the distributor of Innospec in Turkey
Background
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. In recent years. Biodegradability has become a buzzword among increasingly eco-conscious consumers
and many big brands across industry are shifting to more sustainable products with some committing to ambitious targets to transition to 100% biodegradable formulations within the next 10 years.
Innospec offers a wide range of primary surfactants for personal care products including our mild, sulfate-free, isethionate and taurate product lines:
Biodegradability Test Methods
Typically, the biodegradation of organic substances by microorganisms in sewers, wastewater treatment plants (WWTP’s) and receiving environment (surface water, soil and upper sediments) takes place under aerobic conditions i.e., in the presence of oxygen. However, since aerobic biodegradation requires high amounts of oxygen, under certain conditions the availability of oxygen can become rate limiting. Low oxygen levels can be encountered in WWTP sludge digester tanks or deep sediments where anaerobic biodegradation by more specialized microorganisms may take place.
To determine the biodegradation performance of Innospec’s isethionate and taurate surfactants under aerobic and anaerobic conditions, a series of internationally standardized screening level tests have been deployed. These methods range from OECD 301A-F (Ready Biodegradability under aerobic conditions) and OECD 311 (Anaerobic Biodegradability of Organic Compounds in Digested Sludge).
OECD 301 tests are used to screen for ready (fast) biodegradability of chemicals in an aerobic aqueous solution. Isethionate and taurate 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 CO
2 production (OECD 301B) or O
2 uptake (OECD 301D) as an indicator of complete (ultimate) biodegradation to water, CO
2 and nutrients. Positive control/reference substances are included in the test for validation and to prove the viability of the inoculum.
The OECD 311 test is a stringent screening for biodegradability of chemicals in anaerobic aqueous solution. Washed and diluted digested sludge was incubated together with the individual isethionate and taurate surfactants in mineral test medium for 60 days in sealed vessels. The production of CO
2 and CH
4 as a measure of anaerobic degradation is determined by measuring the increase in headspace pressure in the test vessels. A substantial part of the CO
2 produced is dissolved in the aqueous phase or transformed into carbonates. This inorganic carbon (IC) is also measured at the end of the test. Positive control/reference substances are included in the test for validation and to prove the viability of the inoculum.
Results
Innospec’s range of isethionate and taurate surfactants were shown to demonstrate impressive performance in OECD 301 and 311 biodegradability testing as shown in the Figures below.
All isethionate and taurate surfactants meet the criteria for classification as readily biodegradable in accordance with the OECD 301 test guidelines. SLMI was found to be
anaerobically biodegradable in accordance with OECD 311 which also applies to SLI on the basis of read across (since both substances exhibit similar chemical structure). Historical OECD 311 data for SCI is also available which indicate the substance is anaerobically biodegradable (data not shown in figures). 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 compared to SMCT and SMLT, both of the latter substances are also considered anaerobically biodegradable based on read across.
Authors:
James Dawick
Toxicology and Risk Assessment Manager
Innospec Limited
Gonca Tuncer
Business Line Manager Personal Care
Eigenmann&Veronelli
İrem Ulusaraç
Product Manager Fragrances
Eigenmann&Veronelli
