We use elevated to mean that the child’s blood lead level indicates they may have higher lead exposure. As sources of lead in the environment have declined over time, the levels of lead in general populations have also decreased. Therefore, what is considered elevated has also decreased several times over the past few decades. In B.C., it is recommended that children over the Exposure Investigation Level (EIL) of 5 ug/dL are followed up by the Medical Health Officer. Language you may come across in older THEP materials may refer to U.S. language, including level of concern, and reference blood lead levels. EILs indicate when Public Health follow-up will occur, rather than when health effects may be observed. There is no safe level of blood lead. Chronic lead exposure is known to have irreversible lifelong effects on neurological development in children.