Underwriters Laboratories revealed that 12 of the lip products sampled tested positive for lead with the highest levels at 3.22 parts per million, the 'Daily Mail' reported.

Commenting on the findings Dr Sean Palfrey, medical director for the Boston Lead Poisoning Prevention Program, warned that even low-level lead exposure poses a serious health risk and could affect mental health.

"What we know now is that even the lowest levels of lead can harm your IQ, your behaviour, your ability to learn," he told Good Morning America, which commissioned the study.

"If you were serious about the public health aspects of lead poisoning you would not be looking at lipstick," Dr Halyna Breslawec, chief scientist for the Personal Care Products Council, added.

"You would be looking at locations where children live. Do they live near hazardous waste dumps - are they chewing lead-containing paint fragments?" Breslawec said.

Currently there are no standards set by the Food and Drug Administration in the US limiting levels in lipstick and it is up to manufacturers to decide on the safety tests performed.

GMA declined to comment on which lipstick brands had been tested, but said that it had selected a range of colours from department stores and drugstores in the US, the paper reported.

Lead is not intentionally put in lipstick but many colour additives are mineral-based and contain trace levels of lead naturally found in soil, water and air.

"Clearly the concerning part is that more than half of the lipsticks do contain lead, but half of them don't, proving that it's possible to manufacture a lipstick without lead," said Janet Nudelman of the Campaign for Safe Cosmetics.

However, recent findings demonstrate that progress is being made.

A 2010 study by the FDA found the highest lead level in lipstick was 7 parts per million.