The Invisible Threat: How Lead Exposure Compromises Immunity and Organ Function
By: Tyneisha Bradley, Fellow for the 2024 Orleans Lead Testing Study
Background
Lead exposure has been a pressing concern for decades in the United States. It is one of the most common environmental health issues that millions of Americans face each day, while most people are not even aware of the many sources and risks associated with lead. The common cause of lead exposure in humans is ingesting contaminated drinking water, due to the presence of lead pipes in water distribution systems and plumbing fixtures. Other significant sources include lead-based paint in older homes, contaminated soil, and certain consumer products.
Lead is particularly dangerous because it can accumulate in the body over time, affecting nearly every system in the body. There are efforts at the local, state, and federal levels to combat lead exposure in drinking water, with a priority placed on children and pregnant women. Due to the persistence of lead in the human body and its negative impacts on human health and the immune system, there is no safe level of lead in drinking water.
Immune System and the Impacts of Lead Exposure
The immune system is the body’s defending mechanism against foreign pathogens (NIH, 2009), and exposure to foreign chemicals such as lead could compromise the ability of the body to defend against pathogens. The immune system consists of two parts: the innate immune response, which provides immediate, nonspecific defense against pathogens, and the adaptive immune response, which offers a targeted and specific response to pathogens the body has previously encountered.
When humans are exposed to lead, there can be damage at the cellular level that impairs the function of macrophages and neutrophils, both of which are responsible for defense against foreign pathogens in the human body. Lead interferes with the signaling pathways and cellular functions of these immune cells, reducing their ability to respond to infections.
With decreased immunity due to lead exposure, there is increased susceptibility to infections and illnesses, preventing the body from properly fighting them off. Over time, chronic lead exposure can weaken the immune system to the point where it struggles to combat even common infections, potentially resulting in prolonged illnesses and an increased risk of complications. Therefore, reducing lead exposure is critical not only for protecting individual immune health but also for preventing a wide range of associated health problems.
How Lead Exposure Impacts Organ Function
Due to its effects on the nervous system, lead is known to be a neurotoxin. However, the impacts of lead extend beyond the brain, affecting multiple organs in the human body (EPA, 2024).
Liver
The primary function of the liver is to remove substances and chemicals from the blood (detoxification), which can be impacted by lead exposure. Due to the inflammation and oxidative stress created by lead exposure, normal liver functions are disrupted when the hepatic cells become inflamed. This disruption could potentially lead to fibrosis, which is when there is a buildup of connective tissue. Fibrosis of the liver leads to extensive liver damage and can progress to cirrhosis of the liver, severely impairing the liver's function and increasing the risk of liver failure. Furthermore, due to the cumulative effects of lead exposure, individuals who are exposed over time may develop liver cancer.
Kidneys
The kidneys function to filter waste products and excess substances from the blood, regulate blood pressure, and maintain overall fluid balance. Exposure to lead can cause serious harm to the kidneys, leading to nephropathy, a condition characterized by damage to the tubules in the kidneys. This damage impairs proper filtration and results in the presence of excess protein in the urine. With chronic exposure, the likelihood of developing chronic kidney disease increases, potentially progressing into end-stage kidney failure.
Reproductive System
Lead negatively impacts both the male and female reproductive systems.
In men, lead exposure can result in decreased sperm count and quality, leading to infertility. The toxic effects of lead can damage the DNA in sperm cells, potentially leading to genetic defects. Additionally, lead exposure has been linked to hormonal imbalances that can further impair reproductive health.
In women who are of childbearing age, lead exposure can cause an irregular menstrual cycle, reduced fertility, or infertility. For those who are pregnant, pregnancy complications such as premature delivery and spontaneous miscarriage are possible. This is due to the ability of lead to cross the placenta, leading to exposure within the fetus. It is also common for those experiencing pregnancy complications associated with lead exposure to birth a baby that has a low body weight. Low exposure levels in pregnant women may also lead to cognitive and behavioral complications in the child that may negatively impact school performance (Skerfving, 2015).
Cardiovascular System
Lead exposure is commonly associated with high blood pressure levels and an increased risk of various cardiovascular diseases. Lead induces oxidative stress and inflammation, which can cause damage to the endothelial cells that line blood vessels. This damage promotes the buildup of fats, cholesterol, and other substances within and on the walls of arteries, a condition known as atherosclerosis.
Atherosclerosis can lead to the narrowing and hardening of the arteries, which impairs blood flow and increases the risk of cardiovascular events. The impacts of lead exposure on these critical processes and functions in the cardiovascular system can result in heart attacks and strokes, particularly in individuals with pre-existing health conditions.
Resources
Getting Blood Tested for Lead
Due to the ability of lead to remain in the circulatory system, exposure can be determined using a blood test. If someone is suspected of being exposed to lead, it is recommended by the Centers for Disease Control and Prevention (CDC) to request a blood test from a physician. According to the CDC, if a person has lead found in their blood, those results will be reported to the state health department. All blood lead level data goes into a database that has information related to follow-up with a clinical provider and investigations into the source of lead exposure. For more information on blood lead level data in children, please visit the CDC website.
Louisiana Healthy Homes and Childhood Lead Poisoning Prevention Program (LDH): This program offers resources for lead screening and prevention, targeting families with young children. They provide support for lead testing in homes and offer educational materials on reducing lead exposure.
Environmental Protection Agency (EPA): The EPA provides guidelines and resources on reducing lead exposure in drinking water and maintaining lead-safe environments.
National Institutes of Health (NIH): The NIH offers extensive research and publications on the health effects of lead exposure, as well as preventive measures and treatment options.
American Academy of Pediatrics (AAP): The AAP offers guidelines for pediatricians and parents on preventing and managing lead exposure in children. Their website includes resources on screening, treatment, and advocacy.