Why Worry About Lead?

The adverse health effects from lead exposure are well documented and begin at the lowest levels of exposure yet measured. A cumulative toxicant, lead impacts multiple body systems, including neurological, cardiovascular, gastrointestinal, hematological, and renal systems. On a grander scale, 5.5 million premature deaths are attributed to lead exposure annually, with a social cost of $6 trillion.

Children are particularly vulnerable due to their size, higher rate of lead absorption, and hand-to-mouth behavior. An estimated 1 in 3 children is poisoned by lead, as many as 800 million globally. The permanent brain damage that childhood lead poisoning can cause often results in reduced IQ, behavioral problems, and learning difficulties. In adults, lead causes cardiovascular and kidney disease, pregnancy complications, and an increased tendency for violence.

Lead exposure most commonly occurs through the ingestion of lead from sources such as contaminated foods and spices, ceramic and metal cookware, lead-based paint, traditional medicines, cosmetics and cultural powders, children’s toys, and lead pipes, as well as from unsound industrial operations such as lead smelting and lead-acid battery recycling.

Warmer Climates Intensify Lead Poisoning

Levels of lead in children’s blood peak during the warmest months of the year, late summer and early fall. This rise in lead exposure is significant and apparent across multiple populations, locations, and time periods.

In 2014, the CDC found that during the warmest months (August-October), 36% of new lead poisoning cases were identified, more than any other consecutive three-month period. This seasonal trend is influenced by a few conditions: high temperatures, low soil moisture, and an increase in lead’s bioavailability. Human behavior is also impacted by warmer weather, with home windows often left open, and children spending more time in and around the home and outdoor spaces.

The International Panel on Climate Change predicts that global warming is likely to reach 1.5°C between 2030 and 2052. At 1.5°C warming, about 14% of the global population—over 1.1 billion people—will be exposed to severe heat waves at least once every five years, with urban heat islands amplifying the effects. These changes will extend the warm season, and in turn, increase seasonal risk of lead exposure.

Extreme Weather Events Reintroduce Lead to an Environment

A warming climate increases extreme weather events, including droughts, wildfires, and flooding, which have direct impacts on lead exposure. Dryness and drought have been found to mobilize lead-polluted soil, increasing risks of ingesting and/or inhaling lead particles in dust.

Wildfires increase lead levels in an environment through the volatilization of soil, which remobilizes lead particles, and through smoke dispersion. A 2021 study found that following a series of wildfires in California, air lead levels increased to 50 times the average level for communities in a surrounding 20-mile radius. Further, wildfires have been found to double air lead levels up to 200 miles away from the fire site.

Groundwater is impacted by extreme weather events, particularly high rainfall and resulting floods. During these periods of high saturation, soil particles, including lead, are mobilized by highly-conductive topsoil, resulting in the spread of metal contaminants through groundwater systems, which enters people’s homes and bodies as drinking water.

While lead-acid batteries are viewed as an essential tool in adapting to climate change, they also pose a significant risk of lead exposure. Lead-acid batteries contain large amounts of lead, with a standard battery containing over 9 kilograms. Almost all of this lead can be recovered and recycled: in the U.S. and Europe, more than 95% of lead from used lead-acid batteries is recycled. However, in low- and middle-income countries (LMICs), appropriate laws and enforcement mechanisms are lacking and a significant percentage of lead-acid batteries are recycled through informal or poorly-regulated operations that release considerable lead pollution, poisoning surrounding communities. Exposure to such toxic sites has repeatedly caused acute lead poisoning in local children.

As the demand for renewable energy grows, lead mining and recycling can be expected to increase in turn. As a result, the amount of lead in environments will grow, initially in communities where lead mining and recycling occurs, and later through the wider global environment. Until all communities can safely manage and recycle lead-acid batteries, a reliance on this technology in the face of climate change will increase risks of lead poisoning across LMICs, exacerbating existing health and development disparities.

Human Behavior: Migration, Consumer Goods, and Violence

Lead poisoning disproportionately impacts refugees and international migrants due to their frequent occupation of older homes containing lead-based paint, living near or working in lead-using industries (mines, smelters, battery recycling), and their disproportionate use of lead-contaminated consumer goods.

Consumer products are increasingly recognized as sources of lead exposure, both within the U.S. and globally, with products including cookware, spices, cosmetics and cultural powders, toys, jewelry, and traditional medicine showing disturbing rates of contamination. A 2023 study by Pure Earth surveyed 5,000 consumer products purchased in 25 countries. Across the samples, 52% of metal foodware and 45% of ceramic foodware, 13% of toys, and 12% of cosmetics were found to have high levels of lead. These consumer goods pose a particular risk of lead exposure as they can be hand-carried across borders, impacting not just their communities of origin, but those to which individuals immigrate as well.

In a warming world, climate migration is inevitable. The World Bank projects 216 million international climate migrants by 2050, largely from LMICs. The countries faced with impending migration are also those with the greatest concentrations of lead in consumer goods, which will migrate with these individuals to their new communities.

In addition to forced migration, a warming climate is a catalyst for another human behavior: violence. A growing body of research suggests that rising temperatures increase some violent crimes, including homicides, sex offenses, and assaults. The heat-crime relationship is notably stronger in low-income communities, both within the U.S. and in LMICs. Lead poisoning compounds this growing risk, as lead exposure has been found to have a causal relationship with violence. As lead remains unremediated across vulnerable communities, the risk of violence in a warming world poses cause for concern for policymakers.

Economic Considerations: IQ, Education, and ROI

Lead poisoning has a devastating impact on education. Lead causes permanent brain damage, harming the hippocampus, which is critical for learning and memory. As a result, lead poisoning causes an annual global loss of 750 million IQ points in children. In LMICs, learning deficits resulting from lead exposure are equivalent to 2 years of lost schooling. A recent study suggests that lead poisoning is responsible for 20% of the education gap between rich and poor countries.

An educated population is vital to climate mitigation and adaptation. Educated individuals are better at learning, assessing risks, and designing solutions. Even basic literacy makes a notable difference in improving people’s ability to address and adapt to climate change. Faced with a planetary crisis, every community will need as educated a population as possible. Reducing lead poisoning directly results in more intelligent, resourceful, and resilient communities.

As it stands, climate change will worsen the effects of lead poisoning through warming temperatures, extreme weather events, dependency on lead-based technology, and human migration. However, lead interventions can simultaneously reduce lead’s negative impacts and increase populations’ capacity to respond to climate change.

Lead interventions promise a high return on investment (ROI), with interventions projecting a return of up to $20,500 per $1 invested. The high ROI is largely derived from an increase in lifetime earnings amongst projects’ beneficiaries, which can help offset climate change’s negative economic impacts across LMICs. Communities most impacted by lead poisoning are the same ones faced with the most severe economic disruptions as a result of climate change. This also means that these communities will most benefit from lead poisoning solutions, with interventions increasing populations’ resilience, adaptability, health, and economic wellbeing in the face of disproportionate climate impacts.

Looking Ahead

How does solving lead poisoning fit into the global response to climate change? Lead poisoning debilitates a communities’ ability to adapt to the climate crisis by negatively impacting public health, education, and economies. While lead poisoning and climate change require different solutions, without proper interventions, the problems exacerbate each other. By appropriating funding to lead solutions, governments can increase lead surveillance and interventions across communities, including those focused on increased blood lead testing, consumer good surveillance, lead-acid battery recycling, and lead-ridden soil remediation. With each intervention garnering a range of returns, both financial and DALYs, the generated ROI can fund future environmental adaptation and mitigation programs on an individual and mass scale.