Isothiazolinones, including methylisothiazolinone (MIT), chloromethylisothiazolinone (CMIT), and their mixtures (often referred to as MCI/MI), are widely used as preservatives in personal care products, cleaning agents, and industrial formulations. These compounds are effective against bacteria and fungi, but they can cause skin irritation and allergic reactions, leading to increased scrutiny and regulatory guidelines for their testing.
Here are the main testing standards for Isothiazolinones:
1. United States (FDA and ASTM Standards)
FDA (Food and Drug Administration): In the United States, isothiazolinones are regulated as preservatives under the Federal Food, Drug, and Cosmetic Act. They must be tested to ensure they are used within the prescribed concentrations. Testing for skin irritation and sensitization is required for consumer products like cosmetics and personal care products.
ASTM (American Society for Testing and Materials): ASTM standards outline guidelines for testing preservatives, including isothiazolinones, in various applications such as cleaning agents, industrial products, and personal care formulations. Some of the relevant testing standards may include:
ASTM E1447-15: Standard Guide for Toxicological Testing of Consumer Products.
ASTM E1168-15: Standard Guide for Toxicological Evaluation of Cosmetic and Personal Care Products.
2. European Union (EU)
Cosmetic Regulation (EC) No 1223/2009: The EU has strict guidelines on the use of preservatives like isothiazolinones in cosmetics. The European Commission Scientific Committee on Consumer Safety (SCCS) provides detailed assessments of the safety of isothiazolinones, especially focusing on skin sensitization and potential allergens.
For example, the SCCS Opinion on Methylisothiazolinone (SCCS/1512/14) determined that a maximum concentration of 0.0015% (15 ppm) for MIT in leave-on cosmetics was safe, but concentrations in rinse-off products should be higher.
EN 14362-1: This European Standard provides testing methods for determining the presence of various chemicals, including preservatives like isothiazolinones, in textiles.
3. ISO Standards
ISO 22716:2007: This standard, titled “Cosmetics — Good Manufacturing Practices (GMP)”, provides guidelines for the formulation, manufacturing, and testing of cosmetic products, including the use of preservatives like isothiazolinones.
ISO 16128: This series of standards provides guidelines for the natural and organic cosmetic products industry, which includes regulations on the use of preservatives such as isothiazolinones.
4. OECD Guidelines (Organisation for Economic Co-operation and Development)
The OECD Test Guidelines provide a global framework for testing chemicals, including preservatives like isothiazolinones. Testing methods are focused on toxicology, skin sensitization, and environmental impact:
OECD 402: Acute Dermal Irritation/Corrosion
OECD 406: Skin Sensitization Test (GPMT – Guinea Pig Maximization Test)
OECD 471: Bacterial Reverse Mutation Test (Ames Test)
OECD 473: In Vitro Mammalian Chromosomal Aberration Test
5. Skin Sensitization Testing
Human Repeat Insult Patch Test (HRIPT): Often used to test the potential for skin irritation or sensitization for cosmetics and personal care products. Isothiazolinones, being potent allergens, should be tested for their potential to cause allergic contact dermatitis.
OECD 429: Skin Sensitization – Local Lymph Node Assay (LLNA), which is an alternative to animal testing, is used to assess the sensitizing potential of isothiazolinones.
6. Toxicological Testing
Acute Toxicity Testing: Isothiazolinones must be tested for acute toxicity via oral, dermal, and inhalation routes as part of safety assessments for chemical formulations. These tests may follow guidelines such as OECD 423 (Acute Oral Toxicity) or OECD 402 (Acute Dermal Toxicity).
Mutagenicity: Tests like OECD 471 (Bacterial Reverse Mutation Test) and OECD 473 (Mammalian Chromosomal Aberration Test) are used to determine if isothiazolinones have mutagenic properties.
7. Environmental Testing
Biodegradability Tests: Isothiazolinones need to be tested for biodegradability in environmental conditions. These tests help assess the persistence of isothiazolinones in water systems and their potential environmental impact. Some common methods include OECD 301 (Ready Biodegradability) or OECD 310 (Ready Biodegradability – Biological Oxygen Demand).
8. Occupational Safety
OSHA (Occupational Safety and Health Administration): In industrial settings where isothiazolinones are used (e.g., cleaning agents, paints, adhesives), workplace exposure limits (PEL) and testing for worker safety should be conducted according to OSHA guidelines for chemical safety.
Conclusion
Isothiazolinones are subject to a range of safety and regulatory testing to ensure their safe use in consumer products and industrial applications. These standards and testing methods are essential for determining their toxicity, skin sensitization potential, environmental impact, and overall safety. When using isothiazolinones, manufacturers must ensure compliance with the relevant national and international standards, such as those outlined by the FDA, EU regulations, ISO, and OECD guidelines.