The Lead Rating is based on the occurrence and concentration of lead in all vehicle and child car seat components. It indicates the relative concern associated with levels of lead detected in the products in comparison to all other products tested. The rating ranges from 0 to 5, with 0 representing products with the relative lowest concern and 5 the relative highest concern.
Lead is sometimes used as an additive in plastics. Exposure to it can lead to a number of health effects, depending on the exposure level. It can cause brain damage as well as problems with the kidneys, blood, nerves, and the reproductive system. It can also cause learning and behavioral problems.