Lead exposure in womb linked to growing up to become a criminal

Exposure to lead in early years is linked to a higher risk of criminal behaviour, a new study has found.

The research, published in PLOS Global Public Health, suggests an increased probability of criminal activity in adulthood when an individual is exposed to lead either in the womb or during the early years of their childhood.

The scientists - Maria Jose Talayero Schettino of the George Washington University and colleagues - further found that those consistently exposed to high levels of lead are pre-disposed to a range of negative health impacts, including damage to the renal and cardiovascular systems, reproductive toxicity, dysfunction of the immune system and delayed growth.

An evaluation of 17 existing studies, the new results found that more evidence is necessary to strengthen conclusions.

However, significant lead exposure at an early age was linked to outcomes including arrest, incarceration or conviction in some form, with arrests and convictions across several studies analysed by the new research associated with increasing blood lead concentrations stemming from childhood.

Damage to the nervous system from continued lead exposure can result in a myriad of neurological effects, including reduced cognitive function, negative behavioural changes, lowered IQ scores, decreased learning ability, poor memory scores and impaired comprehension abilities.

Lead exposure can occur through pollutants from industrial waste, paint, glazed-clay pottery, traditional medical treatments and batteries. In high-income countries, exposure is more likely to appear through industrial materials, paints and products imported into the country, children’s toys and ceramics.

Previous studies have investigated the relationship between changes in lead exposure and criminal behaviour, identifying what the authors term “positive associations” between air lead concentrations, crime rates and homicide rates.

Studies conducted on animals have also shown impairments in memory, attention, spatial recognition, sensory function and overall learning ability, with exposure in utero and in early years translating to impairment in adulthood. The authors behind the new research argue for “policy action” to prevent exposure to lead, citing this as “crucial to safeguard public health and promote a safer society for all.”

“Children do not absorb or metabolize lead in the same way as adults and are far more susceptible to the negative impacts of lead exposure due to a hyper-permeable blood-brain barrier and rapidly developing organ systems”, the study’s conclusion read.

“This review demonstrates an association between exposure to lead and the later development of delinquent, antisocial, and criminal behaviour. Although borderline levels of risk are seen in several of our included studies, most are above the null value and estimates of risk are generally precise.

“Criminal behaviour exists on a broad spectrum, and each study chose to delineate the limits of that spectrum in a different way. We propose that future studies should be carried out in a more diverse range of countries and focus on adequate assessment and control of relevant confounders and utilize a common set of indicators for both exposure and outcome in order to measure the overall impact of lead through a quantitative meta-analysis.”