(Medical Xpress) -- While there are already laws against such activity in many areas, a new study finds yet another reason to avoid bestiality, or sex with animals. The new study, published in the Journal of Sexual Medicine, finds a link between bestiality and penile cancer.

The study, led by urologist Stenio de Cassio Zequi in San Paulo, looked at 492 men from rural Brazil. The men participating ranged in age from 18 to 80. Of the 492 men, 118 had been diagnosed with penile cancer.

Of the 188 men with penile cancer, 45 percent had sexual relations with animals compared with 32 percent of the healthy males. Of those men who had sexual relations with animals, 59 percent reported having sex with animals for one to five years and 21 percent had been doing it for more than five years.

Sexual interaction occurred as often as daily and included animals such as horses, cows, pigs and chickens.

Researchers believe that sexual interaction between humans and animals may produce micro-traumas in the penis such as scratches and cuts. They theorize that animal secretions may be toxic to humans and that some unrecognized microorganism may be responsible for the cause of penile cancer.

Circumcision seems to also play a role in the development of penile cancer, with males who have been circumcised seeing penile cancer rates near zero. Researchers believe that uncircumcised men may be more at risk of developing micro-traumas. The majority of the men in the study was uncircumcised and may have contributed to the rates of penile cancer.

Penile cancer accounts for as much as 10 percent of male cancer in Africa, Asia and South America. It is however rare in the United States. In the U.S., thirty states have laws connected to animal cruelty legislation prohibiting bestiality.

While bestiality has been a part of history and is described in theater, jokes, folk music and oral traditions, it is not something that has been studied and represented in scientific research. This is the first study to link the practice to genital cancers.

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