Retail giants Wal-Mart and Toys "R" Us have both revised their safety guidelines for suppliers, slashing the maximum allowed amount of lead in surface coatings.

Toys "R" Us announced last week that from next month will require all products manufactured exclusively for its stores to far exceed legal requirements and contain no more than 90 ppm of lead in surface coatings. Substrates in the products must contain no more than 250 ppm. Under federal US guidelines, the ceiling for lead content is 600 ppm.

The company has also pledged to eliminate the use of phthalates in products that it sells by the end of this year. Phthalates are plasticising compounds believed to have negative health effects. Finally, it expects nickel cadmium batteries to be totally eliminated from its product portfolio by year's end.

The move cranks up pressure on the company’s rivals, including Wal-Mart which this week announced that it is to mirror its rival's pledge on surface coatings, but is sticking to the 600 ppm threshold on accessible components in toys.

It has also pledged to reduce levels of "certain phthalates" in toys to a 0.1 per cent maximum. The mandate applies to all orders and reorders of toys, said the company, which will also enforce independent testing of all new toys and reorders against its guidelines, starting next month.

Lorraine Smith, senior corporate social responsibility adviser for Canadian Business for Social Responsibility, argued that such safety standards are part of a wider focus on ethical sourcing. "There's a much bigger issue around overall lifecycle, that takes in the raw materials to the manufacturing, and assembly, through distribution, all the way through to disassembly and disposal," she said. "The lead content in toys is a small piece of that way bigger picture and a lot of companies [are now] looking at their overall product line."

US retailers have faced heavy criticism in recent months over the chemical content of toys following a spate of recalls. The recalls prompted the state of California to last year launch legal action against 20 companies, including Mattel, Wal-Mart and Toys "R" Us, accusing them of selling toys containing illegal quantities of lead.