Derek Ellerman first peered into the sordid world of selling women and children for sex in Rhode Island, of all places. In 1998, the Providence Police Department raided a popular Korean massage parlor and health club — only to discover six Korean women living a life of forced sexual servitude. Rather than treat them as crime victims, the police arrested the women for prostitution. Never mind that they had been lured to the United States with false promises. Never mind that they had been held here with violent attacks. It’s not the most uplifting of stories. But the case inspired Ellerman to help found an anti-trafficking organization known as the Polaris Project last January. Ellerman comes to Boston next week to discuss the state of the sex-trafficking industry — which smuggles as many as 50,000 women and children into the US every year. The Phoenix caught up with him by phone at his offices, in Washington, DC.

Q: How did you estimate that 50,000 women and children are sold annually in the US?

A: That number came from a study by the CIA, which tried to estimate the number of people who are trafficked every year in this country. Many women and children are trafficked into the sex industry, but not all. Other trafficking involves things like sweatshop labor. But the most lucrative portion of human trafficking is sex trafficking. Right now, human trafficking is the third-largest criminal industry in the world, after drugs and arms. It’s the fastest-growing, and many speculate that it’ll overtake drug trafficking.

Q: How difficult is this industry to monitor?

A: It’s extremely difficult because it’s a black-market industry. Because it’s illegal, it’s hard to get numbers. But because the industry depends on customers, it has to be open enough so people can find places where women are sold into prostitution. Very often the biggest problem is the lack of law enforcement monitoring the rings. There’s massive corruption, too. A huge amount of money flows through this industry. In countries like Thailand, Eastern Europe, and Japan, there are close ties between organized crime groups that run the trafficking rings and the money that goes into law enforcement. Here, in the US, the FBI recently conducted raids across the country of Korean massage parlors. In one case, they found a Sunnyvale, California, police officer who was getting paid to protect the brothels. He was even paid to track down women who had run away. He went as far as Hawaii to get them.

Q: How do women and children typically end up in this world?

A: It depends. A common scenario is a woman or a child who lives in a poor area in the world is given the opportunity to travel to the US to get work cleaning hotels or waitressing. For them, it’s an opportunity to support themselves and their families. Often, they go into debt to the people who are trafficking them. They come over here. But when they get here, they find out that the work they’re meant to do is prostitution. In some cases, people pay off their debts over time and then leave. This is difficult, of course, because the people who control the debts are the traffickers. In other rare cases, law enforcement is able to intervene and free the victims. In the US, we passed federal anti-trafficking legislation in 2000 that sets up penalties for traffickers and protections for victims, such as visa status and psychological services. Since then, the FBI has only been able to identify and help 300 or so victims out of an estimated four million. So we’re really at the beginning of our serious anti-trafficking work in this country.

Q: Are there certain areas in the US where sex trafficking thrives?

A: Traffickers have done a good job of extending their operations into suburban and rural areas largely because law enforcement tends to be less organized there. But the primary areas where trafficking occurs are still in the major cities and along the borders, in Texas, Southern California, Michigan, and in New York, Washington, DC, and Atlanta. Boston is considered one of the major hubs for the Northeast, and we’re aware of trafficking cases of Chinese and Thai women. There needs to be more investigation into the levels of trafficking in the Northeast, including in Boston.

Q: What can be done to stop this growing trend?

A: In the US, there needs to be greater prioritization on the federal and local levels to fight this problem. We need to focus more on the demand side and prosecute the customers. Another huge component of the solution needs to be awareness. Americans don’t want this type of thing happening; this is modern-day slavery. As more Americans become aware of the scope of this problem, it will become more of a priority. We’re trying to build an anti-trafficking movement among community members in order to bring public pressure to bear on local authorities to make this problem a priority. I urge people to get involved. Wherever you live, there’s likely trafficking going on, especially in the city. Boston is no exception.

Q: So what ever happened to the six Korean women in Providence?

A: As far as we know, the women were arrested and then handed over to the INS. They got deported. If the police had treated this case as a trafficking case, the women would have gotten various services under the federal anti-trafficking legislation, such as temporary visa status, psychological counseling, medical care, and so on. The case shows just how far we have to go in terms of adequately responding to this issue.

Derek Ellerman will speak about trafficking in women and children on Wednesday, November 20, at 12:30 p.m., at the Women’s Studies Research Center, at Brandeis University. The event is free. Call (781) 237-6826.