Nearly 40 percent of teens have texted or sent an email while driving in the past 30 days, according to a new study published in the Journal of Adolescent Health.

The study of more than 101,000 teenagers found that, the older the driver, the more likely he or she is to text while driving. For example, 15 percent of 14-year-olds said they sometimes or frequently text, increasing to 56 percent of teenagers 18 and older who said they sometimes or frequently text. In most states the law prohibits teenage drivers from using a mobile phone at the wheel.

Texting while driving is associated with other risky behaviors, according to the study. Teens who infrequently wear a seatbelt, for example, are 21 percent more likely to text or email while driving than teens who frequently wear a seatbelt. Students who report drinking and driving are 91 percent more likely to text while driving than those who do not.