Lead paint is the leading cause of lead poisoning cases in the US. Young children or pregnant women living in homes with lead paint are particularly at risk, and even small levels of exposure can result in lowered IQs in children or fetuses. Long-term exposure to lead paint poison may also lead to more severe intellectual development problems. The main source of exposure in these older homes is dust containing lead particles, which may build up around any structure covered in lead paint. This may be invisible to the naked eye, and so it is likely that most people don't realize that they are exposed. Lead test kits are available to test the level of lead paint poison which may be present in any house. If a person suspects that they may have been exposed to lead paint poison, their physician will be able to offer them a test for the level of lead in their blood, and advise them of what to do.