“HARMLESS to humans”, assured the slogan on humidifier disinfectants sold to South Koreans in the early 2000s by Oxy, a local unit of Reckitt Benckiser, an Anglo-Dutch consumer-goods company. A widening criminal investigation by South Korea’s government into dozens of cases of lung disease, some of them fatal, suggests the opposite. It is now examining compensation claims by another 750 victims, on top of the 530 lodged since 2011.

Chemical sanitisation in homes and offices is prized as a sign of the country’s rapid progress since its economic take-off in the 1980s lifted millions from squalor and disease. Killing germs, says Lee Duck-hwan, a professor of chemistry and communication at Sogang University in Seoul, became the “single most important topic of daily discussions” in the 1980s. Since then, everything from baby soap to washing machines has claimed to act as a steriliser—something Mr Lee decries as “phobia marketing”. So it is a particular blow when it turns out that products which should improve cleanliness might do harm.

The government suspended sales of the disinfectants sold by Oxy and three other local companies in 2011, after an investigation into the deaths that year of four pregnant women suggested poisonous chemicals in their products were the cause. A government study recently revealed that exposure to the sterilisers had multiplied the risk of severe lung damage by 116 times. Prosecutors charged three executives at Oxy in May with shirking toxicity tests on the disinfectant. On June 7th John Lee, formerly head of the local unit of Reckitt Benckiser and now boss of Google Korea, was summoned again by prosecutors for another round of questions about the toxic steriliser. South Koreans are incensed that it has taken so long for the government to act, despite their protest campaigns. In the decade after 2001 South Koreans bought over 4.5m of Oxy’s suspect products.

In quick succession in late April, two South Korean retailers who sold the disinfectants under their own brands—Lotte Mart and Homeplus—issued apologies and promised compensation, followed by Oxy itself, which, for the first time, accepted the “fullest responsibility”. Retailers have stopped ordering Reckitt Benckiser products altogether. The government recently said that it had reviewed 15,000 products, from deodorisers to detergents, and had banned seven biocides, the compounds that kill germs, for containing prohibited chemicals.

Nevertheless, the scandal is starting to change the way South Koreans shop. Consumers are shunning laundry liquids, wet wipes and air fresheners. E-Mart, another retailer, says sales of bleach fell by 38% in the three weeks following Lotte’s apology; dehumidifying detergents dropped by almost half. Long-standing customers of Dure Co-op, a network of organic shops in the Seoul region, say even they use chemical detergents because they are more effective at killing germs. But since the scandal they have dumped their Oxy products in a dedicated box at the entrance to the store. Those who do can buy Dure’s alternative cleaning products at half-price, among them an air freshener made from citric acid and plant-derived anti-microbials.

The manager of the co-operative says that more have been buying up “green” household products, especially since the “no-poo” movement, which renounces shampoo, caught on in South Korea last year. South Korean newspapers now refer to this new group as the “no-chemi clan”. Some even make their own products: Bae In-suk is one of ten mothers who meet up regularly in Seoul to make facial soaps since the Oxy scandal has mushroomed.

Mr Lee says the government’s recent promise to catalogue the level of toxicity of every household biocide is impractical. So too, he says, is the no-chemi movement—it is better to educate consumers about how to use products safely. Hwahae, a cosmetics-reviewing app launched in 2013 (by three men who wanted to know what exactly was in their facial products) has already clocked up 2.5m downloads. It lets consumers read up on 1.9m ingredients in 62,000 items. It is always good to know what you are rubbing on your face.