WASHINGTON — A study to be released Wednesday about the world’s oldest profession concludes that the lucrative underground commercial sex economy in eight large U.S. metropolitan areas brings in anywhere from $40 million annually to as much as nearly $300 million.The unprecedented 340-page study by the Urban Institute, a policy research group, finds — not surprisingly — that the reach of the Internet has facilitated the flesh trade and made it harder to combat. The report and its in-depth interviews with 73 convicted pimps and traffickers also challenges conventional wisdom on the illicit side of the sex industry.“We often think about the commercial sex economy as a hustle, where there’s no real thought or planning that’s involved,” said Meredith Dank, the lead researcher on the exhaustive study funded by the Justice Department. “But we found … the opposite — that some pimps and traffickers actually had a business model they followed.”And business has been good. In seven of the eight cities, the commercial sex trade had a combined estimated annual cash value of $975.3 million, the study found. Researchers were unable to estimate the economic size of the business in one city: Kansas City, Mo. In Seattle, the $112 million estimate for 2007 was more than double the 2003 estimate of $50 million.The study did not differentiate between forced and unforced prostitution, but it did have another surprise finding: The recruitment and pimping of women is no longer just a man’s world.“Some of the findings might ruffle some feathers in the end,” Dank said during an interview at the McClatchy Washington Bureau. “One finding is that in some cases women are doing the recruiting of the pimps. Most people want to say all women are the victims and all men are the perpetrators. If we are really going to address this issue, I think it is really important to know the external factors and environmental factors that are pushing people into it.”The study is novel in that it builds off of existing data on the illegal trade of drugs and weapons and uses them as a proxy to construct a model for measuring the economics of the commercial sex trade.“I think it gives you an order of magnitude that hasn’t really existed,” said Bilal Khan, the study’s methodologist and a mathematics professor at John Jay College of Criminal Justice at the City University of New York. “Methodologically, it’s a breakthrough, coming up with an estimate simultaneously for the size of all these illicit activities.”Shared with McClatchy before publication, the study seeks to understand the size and structure of the sex trade through a close look at eight metro areas: San Diego, Seattle-Tacoma, Dallas-Fort Worth, Denver, Kansas City, Atlanta, Miami and Washington. The methodology developed for the study, said Khan, should be usable by other researchers interested in quantifying an illicit activity previously studied mostly from the perspective of law enforcement.While the study is a first of its kind, it’s not without limits. The focus is through the lens of imprisoned pimps and traffickers, and those who put them behind bars. Future studies could break past stigma and focus on the sex workers themselves, said Sienna Baskin, co-director of the sex workers project at the Urban Justice Center in New York, an advocacy group.“I think that people are uncomfortable talking about this issue, writing about it,” she said. “One thing that we’ve noticed: When people are developing policy and laws regarding sex work, sex workers are rarely at the table. There’s not a lot of knowledge because sex workers aren’t represented.”The sex trade has evolved. Gone are the days of colorful brothels, scantily clad prostitutes on bustling street corners or flashy pimps who control a range of illicit activities in a particular neighborhood.Instead, in Washington, many of the women blend in outside popular nightclubs just blocks from the White House. In New York City, sex workers book rooms at hotels like the Liberty Inn, a nondescript corner hotel on the West Side Highway along the Hudson River, which charges $80 for a two-hour stay.The commercial sex trade is widely segmented, the report found. There’s still common street-level prostitution — almost exclusively men and women selling themselves in impoverished neighborhoods to feed a drug habit. The price of the sex act in this commercial activity, say in Kansas City, was almost directly tied to the price of crack cocaine or heroin, researchers said.There’s also a rise in Latino brothels in Miami, Dallas-Fort Worth and other areas. They often operate unnoticed in residential areas of many large cities with large populations of immigrants from Mexico and Central America. Three or four women working together for a pimp may see 100 men each on a Sunday, bringing in collectively $12,000 to $16,000 in a single day.