DUBAI // Researchers into behavioural disorders among the region's children are beginning to wonder if traditional forms of eye make-up are part of the problem.
Certain types of kohl, the popular decorative black eyeliner, contain high levels of lead. And the researchers suspect kohl, when absorbed into the bloodstream, may trigger attention deficit hyperactivity disorder (ADHD).
While the scientists' work is not conclusive, and other factors might play a greater role in ADHD, they say consumers should be aware of the risks.
In some rural regions in the Gulf, the cosmetic is also applied to the umbilical stump of a newborn baby with the belief that it can ward off the "evil eye" later in life.
A recently published paper found the level of lead and other heavy metals in the blood of children suffering from ADHD was higher than in those who were not.
Said Yousef, one of the report's authors and a member of the psychology faculty at UAE University, said kohl may have played a role.
"Some types of kohl contain about 85 per cent lead," he said. "It's one of the reasons why lead concentration increased in the blood.
"However, there are other environmental reasons too, such as the air, water supply and through contact with other lead-based substances."
The lead content of kohl has been studied in the UAE and elsewhere in the Gulf by Dr Ragini Vaishnav, an assistant professor at the college of Sultan Qaboos University in Oman.
She is also planning to study the link between lead content in the blood and hyperactivity disorders.
Dr Vaishnav said it was difficult to tell the extent of kohl's contribution to the level of lead in the blood, as researchers would need accurate information on how long children had been exposed to the cosmetic, and how it had been applied.
"It depends on how you apply the kohl," she said. "If it's applied inside the eye, there's more absorption than there would be than if you applied it outside the eye.
"Similarly, if you apply it to a child and they start rubbing their eyes, or sucking their thumbs, that can all increase absorption.
"There are all kinds of associations which could increase blood-lead levels, indirectly due to kohl use."
Dr Vaishnav conducted an in-depth study in 2006 on the lead content of kohl products found in souqs. Her paper reported that at least 38 per cent of kohl products sold in the Emirates contained lead and other metals.
That study prompted action from local authorities. Officials from Dubai Municipality said that Dr Vaishnav's study prompted them to conduct their own investigation, which confirmed the results.
"Some products contained 50 per cent, or sometimes 80 per cent lead, which was not acceptable," said Naseem Mohammed Abdulla, the head of consumer products safety at Dubai Municipality.
"Back in 2007, the programme was really new. Anything that anyone could manufacture could enter into the market without any control."
She said the municipality adopted strict rules that meant all new products sold in Dubai needed to be registered after passing tests for substances such as lead and arsenic.
Products are allowed to contain no more than 0.005 parts per million of lead, the lowest level that can be detected accurately.
Inspectors carry out daily checks on markets across the emirate to ensure compliance. "We have fewer violations now," she said.
Most offenders were traders selling items smuggled into the country, said Reda Salman, the director of public health and safety at the municipality.
"The violations are probably more in street vendors and places which do not have proper licences or approvals, such as in temporary stores and street traders," he said.
Amal Al Darmaki, a 23-year-old Emirati, started using kohl as a teenager.
"I only buy kohl from shops in the mall," she said.
"It is probably more healthy than the kohl they sell in the souqs - and better quality, too."