Nearly 507,000 women and girls in the United States could be at risk of female genital excision, including 57,000 in California, a new study has found.
That is more than twice the number that were thought to be at risk in 2000, the last year for which estimates are available.
Analysts at the Population Reference Bureau, a nonprofit research organization in Washington, attributed the preliminary findings released Friday to an increase in immigration from countries where the practice is common, including Egypt, Ethiopia and Somalia.
It is unclear how many families continue the practice after moving to the U.S., but community activists say there is anecdotal evidence of girls being sent back to their parents' home countries for "vacation cutting" and of traditional cutters traveling to the U.S. to circumcise girls in this country.
To estimate the number who may have undergone the procedure or be at risk, the research group used data collected by the Census Bureau for the 2013 American Community Survey to determine the number of women and girls whose families originate in countries where female genital excision is practiced. It then applied the prevalence rates in those countries to the numbers in the U.S.
The methodology is similar to that used by the Centers for Disease Control and Prevention in a study that found about 168,000 women and girls were at risk of genital excision in the U.S. in 1990, said Mark Mather, the group's associate vice president for U.S. programs.
Campaigners have been urging the government to update its estimate, and the CDC is expected to release new figures this year.
"What's happening around the other side of the world has implications for families here in the U.S.," Mather said. "We're seeing more and more of this with immigration and economic ties. Issues that most people might not have considered before may be emerging in their small towns and communities."
California is the state with the highest at-risk population, followed by New York (48,000) and Minnesota (44,000), the Population Reference Bureau found.
"California historically has been a very important gateway state for immigrants, and I think that's reflected in the numbers," Mather said.
That is also true for many of the other states with high at-risk populations. But Mather said he would expect to see more of these families spreading across the U.S. in the coming years.
At the same time, he said, "as we get more third-, fourth- and fifth-generation immigrant families, you would expect to see fewer of them holding on to these traditional practices."
Charlotte Feldman-Jacobs, the Population Reference Bureau's gender program director, said she hoped government agencies, healthcare providers and community activists would use the information to ensure U.S. laws are enforced and the affected women and girls receive the care and support they need.
Cutting a girl's genitals for nonmedical reasons has been illegal under U.S. federal law since 1996. In 2013, President Obama signed a law that also makes it illegal to send a girl to another country to have the procedure done.
But Feldman-Jacobs said she knew of just one criminal case being brought in the U.S. for female genital excision. An Ethiopian immigrant was convicted of aggravated battery and cruelty to children in 2006 for removing his daughter's clitoris with scissors at the family's Atlanta-area apartment when she was 2.
There are long-term risks to the women who undergo what is sometimes referred to as female genital mutilation or cutting. The World Health Organization says the procedure can cause recurring infections, increase the risk of complications in childbirth, and in the most extreme form may create a need for later surgeries to allow for sexual intercourse and childbirth.
But in some African, Asian and Middle Eastern communities, the practice is seen as an important coming-of-age ritual that ensures a woman's purity. Without it, she may not be able to marry.