Chemicals found in lipstick, nail varnish and deodorant could be causing early puberty in girls, a long running study of mothers and their daughters suggests.

The research found a linear relationship between exposure of phthalates, parabens and phenols and the onset of puberty in girls, although there was no similar observation in boys.

The link was there both when a daughter had been exposed to the chemicals in the womb, and while growing up.

Phthalates are found in scented products such as perfumes, deodorants, soaps, shampoo, nail polish and cosmetics while parabens are often used as preservatives in cosmetics and other personal care products.

Phenols are mostly found in soap, toothpaste, lipsticks, hairsprays, shampoos and skin lotion to increase the durability of the products, although British companies have stopped using them so often in recent years.

Dr Kim Harley, Associate Professor in Public Health at the University of California, Berkeley, US, who led the study, said: “We found evidence that some chemicals widely used in personal care products are associated with earlier puberty in girls.

“Specifically, we found that mothers who had higher levels of two chemicals in their bodies during pregnancy - diethyl phthalate, which is used in fragrance, and triclosan, which is an antibacterial agent in certain soaps and toothpaste - had daughters who entered puberty earlier.