Hello all and welcome to the Environmental Public Health Tracking (EPHT) Community of Practice (CoP) on Knowledge Hub. The work shown in this CoP is managed by the Environmental Epidemiology Group (EEG) within Public Health England (PHE).
Lead exposure is especially harmful in young children and the developing foetus. Blood lead concentration (BLC) is measured to determine recent exposure and alongside clinical evaluation, helps to guide clinical and public health actions.
Previously, PHE used a BLC of ≥10μg/dL (0.48μmol/L) as the threshold (‘public health intervention concentration’) for public health case management in England as well as the existing case definition for surveillance purposes for children under 16 years old.
However, a recent PHE report evaluating the need for lowering this level further proved the need for this change in England. Therefore, the public health intervention level for blood lead concentration was lowered to the new level of 5μg/dL (0.24μmol/L) on the 5th July 2021.
The report highlighted strong evidence of adverse effects on cognitive function at blood lead concentrations below 5μg/dL (0.24μmol/L), externalising behaviours and delay in sexual maturation or puberty onset in adolescence at blood lead concentration below 10μg/dL (0.48μmol/L). There has been some evidence that the neurodevelopmental effects are irreversible. There was also evidence of a supra-linear dose response relationship with lead exposure and IQ without an identifiable lower threshold below which exposure to lead does not result in adverse effects.
Therefore, harm may occur from any exposure to lead. However, greater exposure to lead results in greater IQ deficit, with proportionally greater harm incurred by initial lower level exposures than subsequent higher exposures. The health effects at BLCs below 5μg/dL (0.24μmol/L) are likely to be sub-clinical and may have a relatively modest impact on an individual however, the cumulative impact on health and wellbeing of potentially multiple adverse effects (for example, separately on IQ, and on externalising behaviour) in the longer term are likely to be more severe, particularly in the context of the socioeconomic and health inequalities of lead exposure.
Members of the LEICSS working and steering groups presented our work at the Royal College of Paediatrics and Child Health- British Paediatric Surveillance Unit Webinar on Lead Toxicity in Children. This is available to watch on YouTube here. There was also further discussion of this in the September 2021 Environmental Protection UK newsletter, where Dr Louise Uffindell wrote about this change and the continued risk of lead exposure in England. You can read more here.
