The legislature in the US Western Pacific island territory of Guam has passed a bill that requires the chemical castration of convicted sex offenders as a condition for granting them parole.

In a narrow 8-7 vote, the Chemical Castration for Sex Offenders Act was passed, according to USA Today. The bill will be forwarded to the governor for signing into law.

Under the pilot programme, the Department of Correction will screen and refer convicted sex offenders to undergo anti-androgen treatment, or chemical castration, one week before they are released.

This procedure will be required on prisoners who are eligible for release on parole within six months.

When a man is either chemically or surgically castrated, he loses use of his testicles. Castration causes sterilisation and also greatly reduces the production of certain hormones, such as testosterone, according to medical experts.

"Thank you to my seven colleagues for passing this measure. With the support of Governor (Eddie) Calvo, Guam will join seven other jurisdictions in the nation and will be the only territory in adopting chemical castration for sex offenders and paedophiles," said author Republican Sen. Brant McCreadie.

Sen. Frank Blas Jr. filed an amendment that will give the pilot programme 48 months to complete.

Last Wednesday, Democratic Vice Speaker Benjamin J. Cruz said the legislation could lead to other legislations.

"Is there going to be a piece of legislation to cut out tongues, cut out hands?" he said sarcastically.

The bill was filed as a response to the FBI's 2013 crime statistics, which showed that in 2013, Guam had a rate of 64.2 reported rapes per 100,000 people — way above the national average of 25.2 per 100,000 people.

Of the 50 states in America, only Alaska had a higher rate than Guam, reporting a rate of 87.6 rapes per 100,000 people.

"The numbers are staggering," McCreadie said Wednesday. "It's frustrating, ... it makes you shake your head."

He said the legislation is a "first step to addressing Guam's rape problem. We need to find solutions, this legislature needs to find solutions."

During the deliberation, senators Tom Ada, Mary Torres, and Nerissa Underwood raised several concerns.

"What we're doing is imposing on their civil liberties," Torres said, adding that "the judicial system allows for people to rehabilitate."