JACKSONVILLE, Fla. -

About half of child booster seats recently tested by the Insurance Institute of Highway Safety could pose a risk to kids, according to statistics from the tests.

That fact has some parents concerned, prompting them to check out the booster seats their children ride in.

"I think it's important we do our due diligence to find out what is good and what will keep our children the safest," parent Christine Sasser said.

Booster seats are designed for children between ages 4 and 8 who have outgrown forward-facing car seats. But a check by the institute shows parents need to inspect the the booster seats they are using because in a number of cases of the straps holding the children in place, the seats may not be positioned correctly.

"There is a final, large category we call check fit, and these are boosters that may do a good job, depending on the size of the child and the vehicle," said Anne McCartt, of the Insurance Institute for Highway Safety. "So these are the boosters where we especially urge parents to check how the lap and shoulder belt are doing."

The institute released its latest recommendations. Using test dummies representing an average 6 year old, it was able to measure the effectiveness of each seat.

Out of 83 booster seats evaluated, a record 31seats were listed as "best bets," meaning they were safe and effective.

Five of the seats evaluated were "good bets," and six were not recommended. Of the six, four are made by Evenflo. Those models are Chase, Express, Generations 65 and Sightseer. Two are made by Safety 1st. They are the All-In-One and Omega Elite.

It all comes to down to the fit, officials said. Lap belts should lie flat across the child's upper thighs and the shoulder belt should cross snugly over the middle of the shoulder.

Not using a seat belt the right way with a booster seat can cause damage in a crash, including spine and internal organ injuries.

To see the complete list of car booster seats evaluated in the tests, go to IIHS.org.