While exposing kids to books will make them smarter, exposing kids to lead will have the opposite effect — and a lasting one, no less. New research suggests children with higher concentrations of lead in their blood grew up to have lower IQ scores.

Researchers measured the blood of nearly 250 babies, and then again periodically for the next 10 years, to determine the amount of lead in their bodies. IQ tests given to these participants as adults demonstrated that the more lead a person had in their system during childhood, the less intelligent they were likely to be. While the lead levels gradually decreased between infancy and adolescence, the early exposure still appeared to alter IQs down the road.

It doesn’t take eating paint chips to make a child’s IQ suffer. In fact, even kids whose lead-levels were deemed “safe” but were on the higher end were still at risk of having decreased intellectual capabilities as an adult.

To keep your kids free of lead poisoning, follow these tips:

1. Check that your home is free of lead-based paint; it was banned in the late 70s, so if your house is old, you probably have some.

2. Ensure that your kids play in sanitary environments, such as away from work sites.

3. Incorporate iron and calcium into their diets, which helps lead not be absorbed.

4. Have your water tested for lead and use a filter either on your tap or a pitcher with built-in filter.

5. Make sure they eat breakfast. Lead is more easily absorbed on an empty stomach.