Lead (Pb) is a potent neurotoxin that has been a global public health concern for many years with chronic Pb poisoning linked to many detrimental public health outcomes. Young children are at particular risk due to their smaller body mass, greater efficiency at absorbing Pb and their developing brains. Blood lead concentrations (BLCs) are typically used to assess Pb exposure and to determine if levels are within blood lead reference values (BLRV). In the UK the BLRV is 5 µg dL-1, in cases where the BLC>BLRV it is recommended that sources of exposure are investigated, intervention measures put in place and monitoring, typically every 3-6 months, is conducted.

To identify potential sources of Pb exposure, samples are taken from the case’s environment to try to identify elevated levels of Pb. In the UK, this might typically include historic leaded paint, water contaminated by Pb piping and contaminated soils. However, despite these efforts, in some cases the source is not readily identified through concentration measurements and/or intervention measures have not resulted in decreases in BLCs.

This has been achieved by the sampling of the individual’s blood and of their environment to perform both total Pb concentrations and characterisation in terms of their Pb isotope composition. The isotope composition of the blood Pb will be inherited from the source(s) of exposure, and therefore dominant sources of Pb exposure will be a strong isotopic match with the blood. By linking information on Pb concentration, Pb isotope composition, and an understanding of an individual’s behaviour a greater understanding of their exposure is achieved. This helps to inform intervention measures and improve health outcomes.

To demonstrate the applicability of Pb isotope ratios in these situations, two case studies are presented in which sources of exposure in children with elevated BLCs were under investigation and Pb isotope ratio analysis assisted in their investigation and identification.