Lead Toxicity

What is Lead Toxicity?

Humans have been using lead in various ways for thousands of years. Along with this usage, there’s a long history of understanding the harmful effects of lead on the human body. Going back as far as the second century BCE, doctors realized that exposure to lead might result in brain and cognitive diseases.

It’s interesting to note that some experts have speculated whether the excessive use of sapa – a syrup made from unprocessed grape juice heated in a lead-containing container and used to preserve wine – could have played a role in the fall of the Roman Empire.

Lead exposure became a widespread issue during the Industrial Revolution, and by the end of the 19th century, doctors started recognizing lead poisoning in children, often due to contact with lead-based paints. As the 20th century unfolded, medical professionals gained a better understanding of the lesser-known and even hidden effects of lead toxicity.

Today, doctors and public health officers face the challenging task of dealing with increasing evidence showing that lead is a powerful neurotoxin. Even at very low levels, lead in the blood can negatively impact brain function. This discovery adds to the difficulties of trying to completely remove lead from children’s surroundings.

What Causes Lead Toxicity?

Lead, a non-biodegradable material, stays in the environment for a long time. Even though the US has put strict restrictions on the amount of lead used in paint for homes, furniture, and children’s toys since 1978, lead-based paint is still a major source of lead exposure for young children. This is partially because many kids live in older homes where lead-based paint was used in the past. As this paint gets older, it can peel, flake, and crumble, turning into dust that settles inside homes and in the soil around the house. Kids can accidentally ingest this dust when they put their hands in their mouths, which is pretty typical behavior for kids.

Another common source of lead is tap water. This is mostly due to lead presence in plumbing. Even though the US Environmental Protection Agency banned using lead in plumbing pipes and solder in 1986, millions of homes are still believed to be supplied by pipes made of lead. In many countries where leaded gasoline is still used, lead-contaminated air from emissions is a major source of lead exposure. Because these emissions can contaminate the soil where food is grown, the lead content in the soil can also impact the food supply. Even though the US stopped using leaded gasoline in the 1970s, levels of lead in the soil in urban areas are still high because of past emissions from leaded gasoline.

There are also lots of jobs and hobbies that could expose adults to lead. When parents who are exposed to lead at work inadvertently bring it home, they could accidentally expose their kids as well. Some of these high-risk jobs and hobbies include metal welding, battery manufacturing and recycling, construction work, and plumbing. And, there are also other less common causes of lead exposure, like contaminated dining ware, spices, and cosmetics that are imported, traditional remedies, or ingesting a foreign object that contains lead.

Risk Factors and Frequency for Lead Toxicity

It’s estimated that about 535,000 children between the ages of 1 and 5 have high levels of lead in their blood. High levels, as defined by the CDC’s Advisory Committee on Childhood Lead Poisoning Prevention, are 5mcg/dL or more. This is determined using data from the National Health and Nutrition Examination Survey (NHANES).

• Children below one year old generally have lower lead levels than 1 to 4-year-olds. This is likely because lead builds up in the body over time and younger children, who tend to move around more and put their hands in their mouths more, can ingest more lead.
• Using data from 2014, for every 100,000 children between 1 to 4 years old, about 444.5 had lead levels between 5 to 9 mcg/dL.
• However, in babies under one year, about 148.5 per 100,000 had similarly severe lead levels.
• Even fewer children had lead levels over 10mcg/dL. For kids between ages 1 to 4, about 50.66 per 100,000 had such high levels, with the number dropping to 19.9 per 100,000 for those under 1.
• Adults also generally have low lead levels. In 2013, only 20.4 per 100,000 working adults (those 16 or older) had a blood lead concentration over 10mcg/dL.

Signs and Symptoms of Lead Toxicity

Lead toxicity can affect people differently, based on how much and for how long they’ve been exposed. In the U.S., while lead levels are high in many children, most don’t show obvious symptoms even though their intellectual development may be affected. Studies highlight that even low concentrations of lead in the blood can affect a child’s IQ and performance in school. This issue is of particular concern because the lower the lead levels, the more severe the impact on each point of IQ.

When lead exposure increases, children can show non-specific signs that are often mistaken as normal toddler ailments. These may include mood swings, stomach pain that’s often linked to poor diet or insufficient fiber, and a lack of appetite, which might be interpreted as fussy eating. Lead exposure in adults can bring about similar symptoms, but due to potentially longer duration of exposure, they may also have higher blood pressure, heart disease, and fertility problems. As exposure and lead blood concentrations continue to rise, symptoms like nerve damage and arthritis can occur.

• Mood swings
• Stomach pain
• Lack of appetite
• High blood pressure
• Heart disease
• Fertility problems
• Nerve damage
• Arthritis

If lead exposure is not arrested, over time, severe symptoms may occur. In children, acute lead poisoning may lead to unusual behavior, slowed development, loss of physical coordination, vomiting, seizures, and in extreme cases, brain swelling which can cause increased pressure in the skull, coma, and death. This most dramatically affects children with extremely high blood lead levels, typically over 70 to 100 mcg/dL. Adults with very high lead levels can similarly suffer from serious neurological issues like confusion, headaches, seizures, and impaired consciousness. These severe symptoms in adults usually don’t occur from regular work exposures, but rather from unusual circumstances like consumption of contaminated traditional remedies or unlawfully made alcohol.

Testing for Lead Toxicity

Screening children for lead levels can depend on the state they live in, as older and urban areas might have higher incidents of lead toxicity. However, a treatment program under Medicaid called Early Periodic Screening, Diagnosis, and Treatment insists that all children with Medicaid should have a lead screening at ages 12 and 24 months. Also, until five years of age, if they have not had a screening before, they should receive one.

According to regulations from the Occupational Safety and Health Administration, employees who might be exposed to over 30 mg/minute of airborne lead for more than 30 days in a year must also undergo lead screening.

A common method for lead screening uses capillary blood as it is quicker and easier to get, but if it shows a high lead result (above 5 micrograms per deciliter), the result should be confirmed with a whole blood sample taken from a vein. If a patient does have an elevated lead level in their blood, they should also be screened to check if they have anemia or lower iron levels. And, if they may have swallowed something that contains lead (for example, a piece of old paint, a metal object like a bullet or a fishing weight), they should consider an abdominal X-ray.

For any situation where someone might have been exposed to a toxin, doctors should get a detailed history of the patient and conduct a physical exam. When it comes to lead exposure, it’s important to learn about the patient’s work, hobbies and home environment (like how old their home is or if any recent renovations have been done), parents’ or caregivers’ jobs (if they are a child), and what their food and water sources are.

Treatment Options for Lead Toxicity

The most important step in managing high lead levels in someone’s blood is to find and remove the source of lead exposure. This often involves professionals from county or state health departments, who can visit the homes of affected individuals, particularly children, to help pinpoint the source of the lead.

If someone has swallowed an object containing lead, doctors will monitor them to ensure the object passes through their system. In some cases, they may need to use laxatives or similar medications to help the object move through the digestive tract, or in severe cases, they might need surgery. It’s also important to make sure the person has a healthy diet, especially foods rich in iron, calcium, and zinc since these nutrients can help to lower the body’s lead levels. If a person’s iron levels are low, they might need iron supplements as well.

Cases where lead levels are dangerously high may require chelation therapy, which is managed by a medical toxicologist. This might include children with blood lead levels surpassing 45 micrograms per deciliter, adults with levels over 70 to 100 micrograms per deciliter, or any person with lead encephalopathy (a severe brain disorder caused by lead exposure). Chelation therapy involves medications known as “chelating agents”. These include succimer, calcium disodium ethylenediaminetetraacetic acid (EDTA), and British anti-Lewisite (BAL, also known as dimercaprol). These medications help to remove lead from the body, but they work slowly and can’t fully eliminate the body’s lead burden. In some cases, they can even be harmful by mobilizing lead from the bones to soft tissues, where damage can occur more easily. Therefore, it’s critical to ensure patients receive plenty of care and support even while undergoing chelation therapy.

What else can Lead Toxicity be?

Generally, most people with high levels of lead in their blood don’t show any symptoms of lead poisoning. This makes it especially difficult to diagnose because mild symptoms can often be overlooked or misinterpreted. Therefore, doctors should include lead toxicity as a possible cause when seeing children with behavior issues or nonspecific digestive complaints, such as constipation, stomach pain, or fussy eating habits.

Even though these types of symptoms are common in toddlers, and not all cases are linked to lead exposure, it’s important not to disregard this possibility. A simple blood test can reveal if a child has lead in their system, which is especially crucial to detect early as it can lead to more serious health problems if the child continues to be exposed to lead.

Similarly, anemia in children might also be linked to lead toxicity, but it can often be mistaken for iron deficiency anemia. Adults with symptoms similar to carpal tunnel syndrome might actually be experiencing peripheral neuropathy due to lead exposure, and older men who consume a diet high in purines and have gout might also have underlying lead toxicity.

Severe cases of lead poisoning can cause symptoms similar to those of infectious or autoimmune encephalitis. Despite the rarity of these cases, it’s important not to skip testing for lead levels, given its widespread availability. Recognizing the potential for lead exposure in various health issues is key to preventing severe lead toxicity.

What to expect with Lead Toxicity

It’s crucial to decrease ongoing lead exposure for people who have high levels of lead in their blood but aren’t showing symptoms. Yet, there’s no proof that reducing this exposure will reverse or improve any potential harm that’s already been done. This is particularly the case for subtle changes in brain function in children.

Patients with mild to moderate symptoms might see an improvement or even complete disappearance of some symptoms, like stomach issues and feelings of discomfort or illness. However, some issues, such as underdeveloped growth in children, may not show any improvement.

Before chelation therapy – a treatment that helps remove heavy metals from the body – the death rate associated with acute lead encephalopathy, an extreme brain disorder caused by lead poisoning, was roughly 65%. After introducing chelation therapy, this rate fell to less than 5%.

However, it’s important to note that these numbers coincided with big improvements in critical care. So, it’s not evident that chelation therapy alone was responsible for the increased survival rate. Also, even after chelation therapy, many patients who undergo treatment for acute lead encephalopathy and survive might still have permanent brain complications, possibly including intellectual disability, weakness on one side of the body (hemiparesis), and seizure disorders.

Possible Complications When Diagnosed with Lead Toxicity

The most common problem related to high levels of lead in the blood, aside from a general decrease in IQ points, is an increased risk of heart disease and death associated with high blood pressure caused by lead exposure. Patients with mild symptoms may have slight complications that can be overlooked, like secondary nutritional deficiencies caused by poor food intake due to constant stomach pain.

As symptoms get worse, the number and seriousness of potential complications increases. Patients needing intensive care unit (ICU) level care because of severe brain damage from lead exposure and possibly increased pressure inside the skull could face the same complications typically seen in critically ill patients, like infections related to hospital devices and confusion caused by the ICU environment.

Potential problems connected to the treatment used to remove lead from the body (chelation therapy) include the risk of causing a deficiency of essential minerals by removing metals other than lead. There’s also a risk of moving lead from the stable bone area to the more unstable soft tissue region.

Specific side effects related to this therapy can include upset stomach (common with succimer and BAL), kidney damage (potentially due to calcium disodium EDTA), and fever, high blood pressure, and rapid heartbeat (BAL), among other things.

Complications of high blood lead concentrations:

• Increase in heart disease and death due to high blood pressure caused by lead exposure
• Secondary nutritional deficiencies caused by poor food intake due to constant stomach pain
• Infections related to hospital devices and confusion caused by the ICU environment in critically ill patients
• Deficiency of essential minerals due to chelation therapy
• Moving lead from the stable bone area to the more unstable soft tissue region due to chelation therapy
• Side effects related to chelation therapy such as upset stomach, kidney damage, and fever, high blood pressure, and rapid heartbeat