What lead concentration threshold in soil is deemed acceptable for safe contact areas?

The threshold for lead concentration in soil that is considered acceptable for safe contact areas is set at 400 parts per million (ppm). This value is based on findings that help protect public health, especially in environments where children may play or where food is grown. Exceeding this level can significantly increase the risk of lead exposure, which is particularly harmful to young children and can result in serious health issues, including developmental delays and cognitive impairments.

The choice of 400 ppm aligns with guidelines from agencies such as the Environmental Protection Agency (EPA), which recommends this threshold as a standard for lead in residential soils. It is crucial for risk assessors to be aware of this threshold during assessments and remediation efforts to ensure safety in environments where potential lead contamination may exist. Understanding this standard helps lead risk assessors make informed decisions regarding safety measures and remediation strategies, ensuring that children and vulnerable populations are protected from the adverse effects of lead exposure.