CHENNAI, India (Thomson Reuters Foundation) - Indian police are investigating the use of growth hormones in a sex trafficking case, following the arrest of eight people charged with exploitation of children in brothels in Telangana state.

Eleven girls, including four below age 7, were rescued from brothels in the temple town of Yadagirigutta where they were being groomed to become sex workers, a senior police officer said on Wednesday.

“The traffickers have confessed to us that they were giving hormone injections to the girls,” said Mahesh Bhagwat, an officer in the state capital of Hyderabad, about 70 km from Yadagirigutta.

“It is a clear case where we see that the girls were being groomed and injected with drugs to look older than their actual age,” he said by phone. “We are also looking for the doctor supplying drugs to the traffickers.”

Of the estimated 20 million girls and women working in India’s sex industry, 16 million are victims of trafficking, according to non-governmental organizations.

A 2017 report by the West Bengal government highlighted the brutal “breaking in” of girls trafficked into brothels, a process that often includes rapes, beatings and starvation.

The use of growth hormones, as well as drugs to sedate girls while they are being trafficked from one place to another, is rampant but rarely investigated, according to campaigners.

“In most rescues, we come across young girls who have been pumped with drugs to look older,” said Rishi Kant, of the anti-trafficking charity Shakti Vahini.

“The police just mention it in their report and don’t bother to investigate this aspect further,” he told the Thomson Reuters Foundation.

The eight traffickers arrested in Monday’s raids had paid families up to 200,000 Indian rupees ($2,917) for each girl, according to a police statement. In other cases, they targeted young orphans.

The doctor supplying drugs to the brothels charged 25,000 rupees ($365) for each girl, the statement said.

Bhagwat said the traffickers attempted to create the impression that the girls were part of a family, even enrolling some of them in school.

“But investigations have revealed that they were in fact being groomed to go into prostitution,” he said.

Uma Chatterjee, a psychologist who works with survivors of trafficking, said the use of growth hormones is a common part of the grooming process.

“Survivors often tell us about the drugs they are given to make them ‘healthier, or prettier, or smarter,’” she said.

Under a new anti-trafficking bill, which is awaiting final approval from parliament before becoming law, injecting drugs will be an “aggravated offense” with stringent punishment, Chatterjee added.

($1 = 68.5650 Indian rupees)