Vast Variations in Cleaning Performance & Costs among Dishwashing Detergents Caution on Choice as Allergic Preservatives Detected in 60% of Samples

15 March 2018
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Vast Variations in Cleaning Performance & Costs among Dishwashing Detergents     Caution on Choice as Allergic Preservatives Detected in 60% of Samples

Dishwashing detergents in the market are commonly claimed to give superb cleaning power, contain “natural ingredients” with eco-labels acquired, and provide “skin caring” or “hand moisturising” effects. But a Consumer Council test on 35 models, comprising regular, concentrated and ultra-concentrated formula detergents, has detected vast variations in cleaning performance – the maximum numbers of dishes that the models could clean were found to vary by nearly 5 times. Based on the test results the costs of cleaning 100 dishes, the greatest variation was found in the regular formula models, which the cheapest and the most expensive models were computed to differ by a staggering 15 times or more. Revealed from the test results, all regular, concentrated and ultra-concentrated formula detergents have cheaper products with higher cleaning performance, hence to make choice consumers cannot merely base on product claims.  
The Council also found some 60% (21) of the models were detected with the presence of allergic preservatives. Among them 5 claimed to be suitable for cleaning fruit and vegetable, while some were labelled with claims: made with “natural ingredients”, “mild” and “gentle on skin”, as well as eco-labels. Furthermore, the product labelling of some 60% of the models was found lacking in information on ingredients used. Manufacturers are urged to improve the descriptions and transparency of their product labelling. Consumers with sensitive skin, on the other hand, are reminded to be sceptical about advertising claims to minimise the risks of skin allergy.
Included in the 35 test models were 23 regular formula detergents, 4 concentrated formula and the remainders 8 ultra-concentrated, weighing from 230 ml to a maximum of 2000 ml, with prices ranging from about $11 to $95 a bottle.
The test was carried out in reference to the German Cosmetic, Toiletry, Perfumery and Detergent Association’s (IKW) Recommendation for the Quality Assessment of the Cleaning Performance of Hand Dishwashing Detergents. In the test, using a standardised amount of detergent and water (4 ml of detergent added with 5 litres of warm water), artificially soiled dishes were cleaned by trained technicians manually with identical brushes until the foam on top of the dishwashing solution could not completely cover the solution surface. The test simulated the situation of cleaning dishes in reality. The more soiled dishes it could clean, the better the cleaning performance of the detergent model.
Cleaning performance
The test results indicated that around 30% (11 models) achieved better performance with more than 22 dishes cleaned – comprising 5 regular, 4 ultra-concentrated, and 2 concentrated models. The greatest variation in cleaning performance was found among the regular formula detergents, between the best (38.6 dishes cleaned) and the least (6.8 dishes) models, the discrepancy was close to 5 times high.
In terms of the different detergent formulations, the 23 regular models could clean on average some 16.7 dishes, the 4 concentrated models 22.9 dishes and the 8 ultra-concentrated 21.3 dishes.
In comparing the different formula models of the same brand, the results showed that the concentrated or ultra-concentrated models cleaned more dishes than their regular formula models by 38% to 215%, i.e. cleaning, on average, about 7 to19 dishes more. In computing the costs needed for cleaning 100 dishes, they ranged from $0.32 to $5.21, which the cheapest and most costly models are regular formula but with a whopping 15 times difference. But if they are not of the same brand, a “concentrated” formula model of one brand might not necessarily perform better than a “regular” formula model of another brand. For example, regarding the cleaning performance, the best concentrated formula model could clean on average 32.6 dishes while the best regular formula model could do on average 38.6; and the concentrated formula model with the worst cleaning performance could only clean on average 15 dishes, less than that of 12 regular formula models. 
The test also affirmed that models with higher amounts of surfactants did perform better. Among the better performing models, 2 were labelled to contain a total amount of surfactants of up to 45% or more. Further, 4 models with SLS or SLES ingredients also fared well in performance. Nevertheless, consumers using detergents with a high SLS or SLES content are advised to wash their hands thoroughly, to avoid any residue left on the skin that may lead to skin irritation.
Allergy-causing preservatives
Detected in 21 models (60%) were allergic preservatives of MIT, CMIT or BIT – 11 of them only with MIT from 6.4 ppm to 78 ppm; 4 with higher amounts of BIT from 93 ppm to 490 ppm; 1 with 9.1 ppm CMIT; and the remainders 5 with 2 of these allergens totalling from 11.6 ppm to 82 ppm. Consumers in daily repeated contact with detergents containing high amounts of allergy-causing preservatives may result in allergic reaction or even dermatitis of the hands. 
According to the recommendation of the EU’s Scientific Committee on Consumer Safety (SCCS) on the safety level of concentration of MIT (15 ppm) in rinse-off skincare products, 9 of the models were measured to contain an amount above the recommended level; 3 models were detected with a high level of CMIT and MIT (exceeding 15 ppm in total), bringing a higher chance of skin allergy. While another model with methanol content was slightly above the maximum allowable limit set by the Mainland’s National Food Safety Standard on Detergents.
In addition, 6 models made the claim that they could be used to clean fruit and vegetable but with only 1 exception all were tainted with allergic preservatives. This, however, was not disclosed on the label. Consumers are cautioned to choose detergents with care.
Product labelling of ingredients
In examining the provision of ingredient information, a high 60% of the detergents were found without listing out their ingredients in detail, making it difficult for consumers to ascertain if the products may contain allergic substances such as fragrance or preservatives. In the case of 7 models that only labelled with surfactants and fragrances/additives, the labelling methodology employed is not very helpful to consumers in really understanding the special property of the products. 12 models were found completely without any ingredient information in Chinese or English. The Council stressed that comprehensive labelling of ingredients is essential to enable consumers to choose wisely products suitable to them, and called on manufacturers to increase the transparency of ingredient information, including their chemical names (e.g. surfactants) and content level, and in the case of allergic ingredients such as preservatives and fragrances, their dates of production and expiry.
Further, 7 of the models carried claims of environmental protection certificates issued by accredited organisations in the US, EU, China and New Zealand. Their performance was more or less comparable to the standard detergent in the test.  But consumers should take note that though the products may be certified to be environmentally friendly, they may still contain allergic substances.
In the choice and use of detergents, consumers are advised to pay heed to the following:
- Study the products’ ingredient lists in detail to detect whether or not they may contain allergic ingredients;
- People with sensitive skin or suffering from eczema or when they have open wounds on their hands, should avoid using products containing MIT, CMIT or BIT preservatives; 
- If necessary wear gloves to wash dishes to minimise contact with irritant or allergic substances; 
- When cleaning dishes, if the dirt is not particularly difficult to remove, use cold water and appropriate amount of detergent, avoid keeping tap water running;
- In removing difficult grease or stains, soak the dishes in hot water first before cleaning them with detergent to save on consumption of the detergent.

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