The hand sanitizers are classified as either over-the-counter drugs (alcohol-based) or consumer cosmetic products (alcohol-free). Their booming market upward trajectory, especially during the COVID-19 pandemic, resulted in an immense increase in production scale, flexibility in regulatory responses, and, unfortunately, the emergence of poor-quality and harmful goods. Strict testing became critical to safeguard human health by ensuring that the presence of active ingredients in the sanitizers (usually ethanol or isopropanol) is of the proper type and concentration, that the products do not include life-threatening adulterants (especially methanol), and that the antimicrobial activity and product stability are up to standard.
Fundamental Principles
The two principles of testing include the determination of the declared active ingredient level and the identification of deleterious impurities. In the case of alcohol-based sanitisers, the main tests are used to determine the concentration of ethanol or isopropanol, as the microbiocidal efficacy of such sanitisers depends on the concentration (WHO and FDA recommend 60-80% v/v ethanol or 70-75% v/v isopropanol). Simultaneously, the products have been evaluated against harmful alcohols such as methanol or 1-propanol that have occasionally been used as alternative and less expensive products, but are very deadly. Other requirements provide stability of the product, both physically and chemically, acceptable pH, and compatibility with the skin, as well as validated microbiological kill claims with accepted test organisms.
Testing Workflow for Quality Control
It is proposed that a typical QC batch release test includes 1) production batch sampling. 2) Identity/assay by GC to verify the type and percentage of active alcohol to ensure that it matches the claim on the label (usually within 5%). 3) Impurity screening through GC to determine the methanol, benzene, and acetaldehyde, among other volatile impurities, against rigid specifications. 4) pH Test with a calibrated pH meter. 5) Physical examination of colour, clarity, and odour. 6) Reporting of all the outcomes in accordance with pre-specification. In the case of new formulations, complete stability and efficacy studies are to be done before they can be approved for the market.
Major Safety Concerns & Adulterants
Methanol adulteration has been a major safety crisis. Methanol is a central nervous system poison and may cause blindness, and is lethal when ingested or absorbed through the skin in large amounts. Methanol-contaminated sanitisers have been associated with hundreds of poisonings and deaths. Ethanol manufacturing or purification had problems, leading to benzene contamination, which is a known human carcinogen, in several brands. The less than 60% alcohol content (active ingredient) makes the product ineffective and gives customers an illusion of safety. There are also toxic inactive ingredients like some denaturants or adulterated glycerin impurities with ethylene glycol/diethylene glycol (EG/DEG), which are also hazards.
Challenges in Testing
In cases of an emergency, labs are overwhelmed with large numbers of samples that need a quick turnaround. Sophisticated Adulteration: This is where defraudsters incorporate materials to either simulate the smell or feel of ethanol or to give positive readings of alcohol content in simple tests. Gels, foams, and emollients added, or fragrance added, may interfere with the methods of analysis, and special sample preparation is needed. Global Supply Chain Variability: Procuring ethanol and other ingredients with various, and in some cases, unchecked suppliers increases the chances of quality and contamination.
Recent Regulatory Actions & Market Surveillance
Following the pandemic, regulators have intensified their market monitoring. The poison control centres and CDC follow the adverse events. This has created a more regulated environment, and a higher level of Certificate of Analysis (CoA) and Good Manufacturing Practice (GMP) compliance is more stringently enforced on all manufacturers, not necessarily only the well-established pharmaceutical organisations.
