Persistent lead exposure linked to cognitive decline, heart disease, and developmental issues—posing ongoing risks despite decades of reduction efforts.
Study: Lead Poisoning. Image Credit: Kim Britten/Shutterstock.com
In a recent review published in the New England Journal of Medicine, researchers found that lead poisoning continued to be a serious health concern despite significant reductions in lead exposure since the 1970s.
Modern levels of lead pose substantial risks of cognitive impairment, cardiovascular disease, pre-term births, and kidney disease.
Modern sources of lead exposure
Historical descriptions of lead poisoning, or plumbism, date as far back as 50 AD to Dioscorides’ De Materia Medica. Although lead exposure levels have decreased significantly since then, with close to 95% reductions observed since the 1970s, the lead levels in the human body today continue to be higher than what was observed in the pre-industrial periods.
Severe lead poisoning begins with headaches, fatigue, irritability, and intense abdominal pain, and high levels of lead in the blood can lead to brain swelling, seizures, and death.
Furthermore, while modern restrictions and safety regulations have reduced the use of lead in Europe and the United States, remnants of lead persist in the environment, in contaminated soil, old house paint, older water lines, and due to industrial emissions.
Battery manufacturing processes, smelting, and improperly discarded electronic waste also introduce lead into the environment in many developing countries. The adoption of leaded gasoline in the 20th century to improve the performance of engines also led to widespread lead contamination in the environment.
Consumer items such as cosmetics, ceramics, and paints were also sources of lead contamination. The geochemist Clair Patterson found that the lead levels in the bones lead levels of individuals living in the industrialized periods were a thousand times that of people who lived in the pre-industrialized periods.
Health impacts of chronic lead exposure
Inhalation and ingestion are the two common modes through which individuals are exposed to lead, and it affects people differently based on factors such as health, age, and environmental factors.
Children living in older homes with lead potentially present in the paint or pipes are especially vulnerable as young children absorb lead more readily, and it can cause serious developmental impairments.
In the body, lead mimics essential minerals such as calcium and iron and enters the cells through channels meant for iron and calcium ions.
Lead also gets stored in the bones, and the lead levels in the blood, which is also the primary biomarker for detecting lead exposure, can increase when the lead stored in the skeletal system is released, especially during periods of increased bone metabolic activity, such as menopause.
Chronic low-level exposure to lead has also been linked to cognitive deficits in children, leading to behavioral and attention deficit disorders, and has been known to contribute to increased risk of kidney problems and cardiovascular disease in adults.
Studies have also found that even small increases in the levels of blood lead can reduce the intelligence quotient (IQ) in children.
Among adults, higher levels of lead in the blood correlate to an increased risk of atherosclerosis, hypertension, and cardiovascular disease, which can all ultimately lead to premature mortality.
The use of leaded gasoline during the 20th century led to the highest levels of lead exposure and the deposition of lead in the environment, and although leaded gasoline has been phased out, communities that live near pollution sources, or in older infrastructure continue to face the risks of lead exposure.
In response to emerging evidence from a staggering number of studies, public health guidelines in many countries have lowered the acceptable levels of lead in blood. Recent health standards have indicated that no amount of lead exposure can be considered entirely safe.
Preventive public health strategies
The global impact of lead exposure remains a grave concern, especially in developing or industrializing countries, where the rates of lead poisoning have increased in recent times. In developing countries, more than 600 million children have blood lead levels greater than 50 micrograms per liter.
Statistics from 2019 indicated that lead exposure was responsible for 30% of the global burden of intellectual disability, and the economic burden of lead poisoning was estimated to be approximately 6 trillion dollars, which is about 7% of the global gross domestic product (GDP).
These figures indicate that regular screening and monitoring of blood lead levels is essential for high-risk populations such as children growing up in older homes, workers in certain industrial fields, and specific groups that have high exposure risk.
Furthermore, chelation therapies using agents such as ethylenediaminetetraacetic acid or EDTA have shown mixed results, with some studies reporting modest renal and cardiovascular benefits of EDTA therapy for lead exposure, but the effects on cognitive outcomes in children being inconsistent.
Conclusion
Overall, prevention remains the most essential strategy for mitigating the risk of lead exposure. Eliminating lead-based products and minimizing the sources of lead in the environment remain the most promising avenues.
These efforts will require public health policies and government support, including the banning of leaded aviation fuel, reducing lead contamination in the soil, and replacement of old infrastructure such as lead pipes.
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