What Is Heavy Metal Poisoning?

Heavy metals are a big problem and can make people sick. Even though these metals do not help our bodies, they can still harm us. These metals can hurt our health and also the environment.

Heavy metal poisoning happens when the body gets too much of certain heavy metals, which can mess up how our body works. Metals like lead, mercury, arsenic, cadmium, and chromium are examples of ones that can cause this problem. We can get exposed to them from our food, medicines, surroundings, or activities.

How bad are the heavy metals depends on how much we are around them and the exposure of the metals on us. Metals like arsenic (As), cadmium(Cd), chromium(Cr), copper, lead(Pb) and mercury(Hg) are really bad for us, even in small amounts, so it's important to know about them. This helps us protect ourselves from too much exposure.

Overview

In small amounts, some metals are needed for good health, but in larger amounts, they can be harmful. Too much of these metals can hurt our bodies. They can make us tired and damage important organs like the brain, lungs, kidneys, and liver. Even our blood and muscles can be affected.It can mimic diseases such as multiple sclerosis, Parkinson's, Alzheimer's, and muscular problems. Sometimes, being near these metals too much can even cause cancer.

How much harm these dangerous materials can bring depends on the length of exposure to the metals. These materials get into our bodies through the food chain. If we're around them for a long time by touching them, eating contaminated food, or breathing them in, we can get different health problems. Another big problem is when the soil is polluted with these materials, which is becoming a big concern all over the world.^1,2

Common heavy metals 

Sources and causes of toxicity

Some common heavy metals that can contaminate the environment include mercury, cadmium, arsenic, chromium, nickel, copper, and lead. Moreover, industries use these heavy metals for different jobs, but sometimes they escape into the air when things are burned or into the soil and water as waste. Even things like paints, makeup, pesticides, and weed killers contain heavy metals. Rain and erosion can carry these metals to other places in soil and water.⁸

When our bodies come into contact with harmful metals, and they get inside, many things start happening. These metals can mess up the ways our body's processes work or even stop them. This leads to many bad effects on both people and animals. It can cause problems like organ, hormone and metabolism dysfunction, messed-up, birth defects, weak immune systems, and even cancer. Because of these issues, guidelines around the world exist to spread awareness about how much of these metals can be in the environment, our food, and our drinking water.^1,4

Some common heavy metals that often contaminate the environment are mercury, cadmium, arsenic, chromium, copper, and lead.⁵ 

• Mercury: Children can be highly affected by mercury. If they're exposed to it before they're born, it can affect their growth and how their heart works. High mercury levels have been linked to higher blood pressure in children. In adults, too much mercury is connected to problems with fats in the blood. Studies have shown that when people are exposed to mercury, the enzymes in their liver increase.^5,10
• Cadmium: Cadmium (Cd) is a harmful heavy metal that can affect the inside lining of our blood vessels and make substances that can cause clotting, leading to more signs of inflammation. Researchers have found that Cd might make cancers grow and spread. For breast tumours, Cd can weaken the body's natural defences against damage and make harmful substances called Reactive Oxygen Species, ROS, when it's around.^5,10
• Arsenic: It is a dangerous metal found in rocks, water, and air. It can cause cancer and other health problems, both short-term and long-term. For pregnant women, exposure to arsenic can lead to higher blood pressure during pregnancy. This can be risky for both the mother and the baby, leading to potential heart problems.^5,10
• Chromium: Chromium (Cr) building up in our organs can be bad for our health. It can harm cells in our bronchial tubes. Cr is also known to cause cancer, especially lung cancer. When you're exposed to a lot of Cr, your skin might get darker.^5,10
• Copper: Copper (Cu) helps in brain health and the production of sperm. Copper can mess up how calcium, iron, and manganese work, which can lead to more cell damage and maybe even problems with our brains as we get older.^5,10
• Lead: Lead is a metal that doesn't break down naturally and is found in small amounts in nature. But because of things people do like making stuff, digging for resources, and burning fuels, there's more lead in the air now. Lead is harmful if we have too much of it in our bodies. Kids are even more at risk. When they touch things with lead dust on them, they can get sicker from it

Signs and symptoms

Heavy metal poisoning can show various signs and symptoms ^3,4,7,9 depending on the specific metal and the level of exposure. Here are some general symptoms that might occur:

• Nausea
• Diarrhoea: Frequent watery bowel movements.
• Discomfort or cramps in the stomach area.
• Headaches: Pain in the head, often severe.
• Fatigue: Feeling very tired and lacking energy.
• Muscle Weakness: Not having as much strength as usual.
• Neurological Issues: Problems with the brain and nerves, which might lead to confusion, memory issues, or difficulty concentrating.
• Skin Problems: Rashes, itching, or changes in skin colour.
• Respiratory Issues: Breathing problems, coughing, or chest discomfort.
• Kidney Damage: Changes in urination, like needing to go often or having pain when you do.
• Liver Problems: Yellowing of the skin and eyes (jaundice) and changes in liver function.
• Cardiovascular Symptoms: Irregular heartbeats, high blood pressure, or other heart-related issues.
• Joint Pain: Discomfort in the joints of the body.
• Mood Changes: Feeling anxious, irritable, or depressed.
• Hearing or Vision Issues: Problems with hearing or seeing clearly.
• Behavioural Changes: Unusual behaviour or personality changes.

It's important to note that the symptoms can vary greatly depending on the specific metal, the level of exposure, and individual factors. If you suspect heavy metal poisoning, it's crucial to seek medical attention for proper diagnosis and treatment.^4,9

Diagnosis and testing

Healthcare providers can use various tests to confirm heavy metal poisoning ^{3,5, 10,13}

• Doctors use blood, urine, hair, nails, and tissue tests to confirm heavy metal poisoning.
• Patients should avoid seafood before tests, especially if they have gadolinium or iodine contrast.
• Workers exposed to heavy metals need regular blood and urine tests to stay safe.
• Special containers ensure accurate samples.
• Blood and urine levels show current exposure, not long-term buildup.
• Additional tests like hemogram, liver, and kidney function tests help diagnose issues.
• X-rays can reveal metal in the body or lung changes from metal exposure.
• Specific tests like the beryllium lymphocyte proliferation test (BeLPT) and Chronic Arsenic Intoxication Diagnostic Score (CAsIDS) help identify sensitization and chronic toxicity risk.¹⁴
• New biosensors quickly detect metal pollution in water bodies.
• Advanced technologies help uncover the links between heavy metals and cancer.

Treatment and prevention

People and families need to be cautious about heavy metal content in everyday things like regular foods, health products, and natural remedies. Extra care is necessary when taking care of young children, especially if living in older homes.³ Workers in industries and those in risky situations should get regular check-ups to make sure they're not exposed to harmful metals. They should follow safety guidelines to avoid exposure. Learning about these precautions should be a continuous process. Industries should take responsibility for safely getting rid of waste and should work with health and local authorities to make sure they're doing it right.³,⁵

Various treatment methods used to detoxify individuals from heavy metal toxicity are:¹³

• The patient is removed from the source of toxic exposure.
• Methods like gastric lavage, activated charcoal, and skin cleaning can help remove heavy metals.
• Supportive care includes IV fluids, oxygen, and other treatments if needed.
• In severe cases, treatments like hemodialysis, plasma exchanges, and ECMO might be used.
• Chelating agents are specific treatments that bind to metals and form compounds that can be removed from the body.
• An ideal chelating agent would be highly soluble, easily enter cells, bind to toxic metals, work well orally or through injections, and be eliminated quickly.
• Plant products are being researched as potential alternatives to chelating agents, especially in places with limited resources.
• Different chelators are used for different metal toxicities:
  1. DMSA is effective for lead (Pb) and mercury (Hg) toxicity.
  2. A combination of deferasirox and deferiprone is effective for cadmium (Cd) toxicity.
  3. 2,3-di-sulfanyl-1-propane sulfonic acid (DMPS) or DMSA work for arsenic (As) toxicity.¹⁵
• Antioxidants, selenium, and vitamin E can aid in treating heavy metal toxicities.

Healthcare providers should be aware of the possibility of heavy metal toxicity, especially if regular treatments don't work. Toxicologists, occupational health experts, community medicine doctors, and environmental engineers all have roles in controlling heavy metal toxicity in different places and preventing harm. Proper coordination among all healthcare providers is vital to reduce the impact of heavy metal toxicity and keep people safe and healthy.

Summary

Heavy metal poisoning happens when we're exposed to too many harmful metals like lead, mercury, and arsenic. It can come from food, water, air, and job environments. Symptoms range from nausea to severe organ problems and even cancer risks. Diagnosis involves tests like blood and urine analysis. Treatment includes removing exposure, supportive care, and occasionally chelation therapy. Preventing it requires education, proper waste disposal, and teamwork among healthcare experts.