Underperforming of 3 Antibacterial Hand Washes – 40% of Models Contained Allergy-causing Preservatives

15 July 2019
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3款抗菌洗手液杀菌较表现逊色	4成样本含可致敏防腐剂

City dwellers are health conscious. As many products claim to have antibacterial function/ability, the Consumer Council has conducted test on a total of 35 hand wash products of which15 models claimed to have antibacterial function while 8 out of these 15 models even claimed to have 99.9% efficacy in killing germs. However, among the regular hand wash products, 3 models were found also to attain bactericidal efficacy on two kinds of test organisms up to 99.5%. In addition, the test detected allergy-causing preservatives CMIT and/or MIT in 13 models. Among them 3 exceeded the limit laid down by the EU or the Mainland China while some models were found with discrepancy between the ingredients labelled and their actual contents.

The Council pointed out that antibacterial hand washes in fact have very limited additional health benefits to consumers. On the contrary, overuse of antimicrobial agents may even lead to development of drug resistance bacteria. Consumers should focus on the proper hand washing procedures and washing time instead of blindly looking for antibacterial hand washes as the only choice. The Council also called on manufacturers to ensure their product labelling is comprehensive and accurate; otherwise, consumers have no way of finding out the product ingredients that may increase the risks of adverse skin reactions.

Among the 35 test models, 20 were regular hand washes and 15 claimed to have antibacterial function. In terms of the form of hand washes, 7 models were packed in bottles fitted with a pump to squeeze out the hand washing foam, while the other 28 models used a more traditional way of adding water to work out the lathers. Prices among these 35 test models varied significantly, from the cheapest $12 to the most expensive $275 a bottle, representing a difference of nearly 22 times. The discrepancy became even more significant at 46 times when calculated on their unit cost per ml (or gram), the price range widened from $0.02 to $0.95/ml. On overall performance rating, the most expensive one ($0.95/ml) and the 2 cheapest ones ($0.02/ml) were equally rated with 4 points, proving once again price and quality are not necessarily correlated.

Bactericidal Efficacy of 15 antibacterial hand wash products

Bactericidal efficacy test was conducted with reference to all European standard to assess their efficacy in killing test organisms: Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). The results showed that the 15 models varied in their efficacy in killing E. coli with 3 models achieving as low as below 41%. As regard S. aureus, their bactericidal efficacy was better with 14 models achieving 99% and only 1 model at 81.1%. 

Among the 8 models that claimed to “kill” or “destroy” 99.9% of “bacteria” or “germs”, only 2 could live up to their antibacterial claims in the elimination of s. aureus and E. coli; 2 models were barely effective against E. coli with a killing rate of 33% and 31%; the remaining 4 were just slightly lower than their claims.

Bactericidal efficacy of 20 regular hand wash products

Out of the 20 regular models, 3 models were found with a killing rate of 99.5% or more against s. aureus and E. coli. The 3 models were strong alkaline with pH values between 9.6 and 10.0. Another 2 models with a killing rate of 85% were, however, comparatively acidic with pH values between 4.5 and 5.2. Both extremes in pH value means the environment is not favourable to the growth of bacteria, and that probably accounts for the bactericidal efficacy of the 5 models. Consumers, however, should be wary that repeated and prolonged contact with strong acidic or alkaline products will increase the risk of skin irritation.

A number of health-related organisations and research studies have emphasized that the objective of hand washing is to clean dirts and reduce the number of bacteria on the skin to a safety level; it is more important to rub thoroughly all surfaces of the hands and rinse thoroughly under clean running water, rather than to kill germs on the skin. The use of regular hand washes together with clean water is adequate to avoid the spread of germs and prevent infectious diseases. 

3 models containing allergens in excess of EU limit

In the test for allergens, nearly 40% (13 models) were detected with preservatives more prone to induce allergy. The results showed the presence of MIT in 3 models, CMIT in 8 models and a mixture of CMIT and MIT in 2 models. Both substances could lead to itching of the hands or even development of hand dermatitis. 

According to the Mainland’s Safety and Technical Standards for Cosmetics, concentration of MIT in rinse-off cosmetics should not exceed 0.01% whereas CMIT/MIT mixture should not be more than 0.0015%. Last year, the EU’s Cosmetic Regulation stipulated even stricter control, reducing the MIT limit to 0.0015%. In the test, 2 models were detected with MIT content of 0.0054% and 0.0058%, though in compliance with the Mainland’s standards, they have exceeded the EU limit. 1 other model was also found to contain CMIT/MIT content of 0.00307%, exceeding both the limit of Mainland and EU requirements.

Despite the CMIT and/or MIT content of most models were within the Mainland and EU regulatory requirements, the labelling information of some models are clearly in need of improvement. 4 models detected with CMIT and/or MIT were without any label indicating that they contained allergen ingredients. In other 2 models, their declared values on the labels were different from the actual test results.

5 models were found to contain free formaldehyde from 0.0066% to 0.4% but all were still in compliance with the Mainland and EU requirements. 1 model, however, did not indicate its formaldehyde-releasing ingredient on its label. People who is sensitive to formaldehyde should beware of the risk that even in contact with small quantity of formaldehyde could lead to adverse skin reactions, including allergic contact dermatitis, itchiness and rash.

Furthermore, 5 antibacterial hand wash models were found to contain chloroxylenol (PCMX), though in compliance with the Mainland and EU requirements, only 1 model had labelled it as the ingredient for consumer information. PCMX is added in cosmetics as preservative or antimicrobial agent, some patients with skin dermatitis on contact with products containing PCMX may develop skin allergic reactions and they should exercise care in using the products.

Consumers should pay attention to the following proper hand washing procedures:

- Wet your hands, apply hand wash on both hands and rub your hands for at least 20 seconds (about the time taken to hum the Happy Birthday song twice), then rinse your hands under clean running water;

- Besides the palms and backs, do not forget to scrub also the thumb, the wrist and between the fingers and under the nails; 

- Before meal and food preparation, always wash your hands thoroughly with hand wash and clean water.

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