The Graco Snugride 35 (which sells in South Africa for R3486) is apparently either the best or the worst, depending on the colour of the upholstery.

More than half the children's car seats sold in the United States contain hazardous chemicals.

Sixty percent of 150 car seats tested by the Michigan-based Ecology Centre were found to contain chemicals such as bromine and chlorine, which points to the presence of polyvinyl chlorate (PVC).

Studies have shown flame retardants containing bromine can permanently affect children’s brains, while PVC has been classified by the US Environmental Protection Administration as a known human carcinogen.

When PVC is burned or dumped in landfills, dioxins - highly toxic chemicals that build up in the food chain and can cause cancer, as well as harm the immune and reproductive systems - are released into the air and water.

The Ecology Centre report said: “Heat and UV exposure in cars can accelerate the breakdown of these chemicals and possibly increase their toxicity.

“Babies are the most vulnerable because their immune systems are still developing and they spend many hours in their car seats.”

Researchers compiled a list of the best and worst car seats in terms of the chemicals found in them, and posted it on the website.

Team leader Jeff Gearhart said levels of bromine varied between different models of the same make, with the source usually being a flame retardant used in the upholstery or cushioning.

The least toxic infant seats were Italian brand Chicco's KeyFit 30 in the Limonata color scheme, Graco Snugride 35 in Laguna Bay and Combi Shuttle 33 in Cranberry Noche.

Two Graco infant seats with different upholstery - the Snugride 35 in red and black and Snugride 30 in Asprey - were meanwhile among the most toxic.

The Ecology Centre has conducted more than 20 000 tests for toxic chemicals on about 7000 consumer products since 1997, using an x-ray fluorescence machine the identifies their chemical constituents in less than 60 seconds. - AFP