Washington, Aug 27 - Allowing teens to work too many hours at the wrong place can derail their sexual health by prompting them to bed older partners. This is one of the key findings in a University of Michigan study of youth on what predicts the age of sex partners.

Study co-author Jose Bauermeister, assistant professor in the University's School of Public Health, says the age difference of sex partners is important because a larger age difference is associated with riskier sexual behaviour and sexually transmitted diseases (STDs), including HIV.

Working too many hours in an adult environ without adequate supervision can lead to exposure to adults and eventually sexual activity with older partners, especially for young girls, Bauermeister said.

His team followed youths in Michigan as they transitioned from adolescence to young adulthood - aged 14 through 25 - to see what factors predicted the sex-partner age- difference.