Bleaches fail to meet standards

PUBLISHED : Thursday, 16 July, 2009, 12:00am
UPDATED : Thursday, 16 July, 2009, 12:00am

Most household bleaches would kill fewer germs than expected if they were diluted according to the 1:99 ratio the government suggests, the Consumer Council said yesterday.

The concentration of an active ingredient in the bleaches, sodium hypochlorite, determines how effective they are. The government suggests people mix one part of bleach with 99 parts of water for environmental disinfection. That suggestion is made on the assumption that bleaches contain 5.25 per cent of sodium hypochlorite.

But of 29 brands tested by the council, 21 contained concentrations of sodium hypochlorite less than 5.25 per cent, and would be less effective than expected if they were diluted according to the government's suggestion, the council said.

Three brands contained marginally less sodium hypochlorite than 5.25 per cent, and another 18 had concentrations of only 1 per cent to 4.8 per cent.

Tin Loong Bleach was the one with the lowest concentration of the chemical, the council said. The brand's label did not state what amount of sodium hypochlorite was supposed to be in the mixture.

Some brands contained less sodium hypochlorite than claimed on labels. Poly Clean Bleach contained 3.6 per cent of the chemical, less than its claimed level of approximately 5.9 per cent (plus or minus 0.3 per cent). The company did not respond to a South China Morning Post inquiry.

Another seven bleach products were also found to contain less of the chemical than stated by double-digit percentages.

Test findings were forwarded to the Customs and Excise Department for consideration as to whether the products violated the Trade Descriptions Ordinance.

The vice-chairman of the council's publicity and community relations committee, Ron Hui Shu-yuen, said consumers should use bleaches when they were 'fresh'. Sodium hypochlorite can decompose when it is placed in a hot environment or in direct sunlight, manufacturers say.

To select the most effective bleaches, consumers should note the manufacturing date and expiry date of products.

A Customs and Excise Department spokesman said it would study the council's report and evaluate the chemical properties of the bleaches involved to check whether the products violated the ordinance.