Earthwise Dishwasher Powder has been recalled after a Consumer NZ test found the product was highly corrosive and failed to comply with a safety standard for hazardous substances.

Consumer NZ chief executive Sue Chetwin says the powder, sold in supermarkets nationwide, was advertised as "naturally powerful and naturally kind".

However, testing found it had a pH of 13.2. Since 2007, the Cleaning Products (Corrosive) Group Standard has prohibited sales to the public of automatic dishwasher detergents with a pH higher than 12.5.

Consumer NZ has previously reported on cases where children have suffered severe burns to the mouth, throat and airways after eating dishwasher powders with a high pH.

Some of these burns were so severe the children required numerous operations to repair damage caused by scar tissue.

After Consumer NZ advised Earthwise of the test results, the company removed existing product from shop shelves. A public recall was issued on 23 August.

Earthwise says anyone who has bought the product can return it and get a refund.

"Earthwise told us it's now changed its blending method and said it was confident there would be no recurrence of the issue. While we're pleased the company has addressed the problem, we're extremely concerned the product failed to meet the pH standard.

This standard was introduced to minimise the risk of harm to young children from automatic dishwasher powders. All manufacturers should be complying with it," Chetwin says.

She says marketing of the product as "naturally kind" was also likely to mislead consumers into thinking that it was a safer choice. With a pH of 13.2, that wasn't the case.

This isn't the first time Consumer NZ was found problems with marketing of "green" products.

"Companies making green claims need to ensure any claims are accurate, unambiguous and verifiable. Otherwise they shouldn't be making them," Chetwin says.

Earthwise Dishwasher Powder is one of 19 dishwasher powders and tablets tested by Consumer NZ in August. While the Earthwise powder was the only detergent with a pH higher than 12.5, all automatic dishwasher detergents need to be used with care as they often contain corrosive substances that cause chemical burns if eaten, left on the skin or if they get into your eyes.