Leading experts are calling for a radical overhaul of regulations for chemicals to protect children from every-day toxins that may be causing a global ''silent epidemic'' of brain development disorders such as autism, dyslexia and attention-deficit hyperactivity disorder.

In a review published in The Lancet Neurology on Saturday, Dr Philippe Grandjean from Harvard School of Public Health in Boston and Dr Philip Landrigan from Mount Sinai School of Medicine in New York said regulations were inadequate to safeguard foetuses and children from potentially hazardous chemicals found in the environment and everyday items such as clothing, furniture and toys.

The pair said that in the past seven years the number of recognised chemical causes of neurodevelopmental disorders doubled from six to 12. These include lead, arsenic, pesticides such as DDT, solvents, methylmercury, found in some fish, flame retardants, often added to plastics and textiles, and manganese, a commonly mined metal that can get into drinking water.

The list also controversially includes fluoride, a mineral found in water, plants and toothpaste. Many health authorities, including the World Health Organisation and Australian governments, say low levels of fluoride in drinking water are safe and protect teeth against decay.

However, Dr Grandjean and Dr Landrigan said a meta-analysis of 27 studies, mainly from China, had found children in areas with high levels of fluoride in water had significantly lower IQ scores than those living in low-level fluoride areas.