What is Mercury Toxicity?
Mercury, a chemical, has been used for a very long time in various ways, including in medicine and in many industries. As a result, it’s quite common for people to be exposed to mercury, and it is also a widespread pollutant in our environment. There are various forms of mercury, each of which can lead to different types of mercury poisoning.
What Causes Mercury Toxicity?
Mercury is found in different types, or forms. These include organic mercury and inorganic mercury. Inorganic mercury can be broken down further into two types: elemental mercury, which is also known as “quicksilver”, and mercury salts. You might be exposed to elemental mercury by using devices that contain it, like thermometers. Exposure to mercury salts can happen when someone swallows a disc battery or uses too many laxatives.
Organic mercury also has two types: short-chain and long-chain compounds. The usual exposure to organic mercury happens when you eat seafood that’s contaminated, use paints that have mercury in them, or swallow or inject something called thimerasol.
Risk Factors and Frequency for Mercury Toxicity
In 2013, there were 1300 recorded instances of mercury exposure in the United States, and only 24 of these had moderate to severe effects. However, in other parts of the world, mercury exposure is much more common and can be harmful. This exposure can come from mercury mining in China, small-scale gold mining, or food contaminated with mercury. There have been some serious cases of mercury poisoning, like in Minamata Bay, Japan, and Iraq. In both these incidents, people were poisoned after eating food contaminated with a toxic form of mercury known as methylmercury.
Children, unborn babies, and fetuses are more likely to be harmed by mercury, and the symptoms can be quite severe. The most common way people ingest mercury is by eating fish that have been exposed to mercury. Because unborn babies are particularly vulnerable, the FDA recommends that pregnant or breastfeeding women and children avoid eating fish with high levels of mercury. Such fish include:
- shark,
- king mackerel,
- tilefish,
- swordfish, and
- tuna.
In addition, certain types of freshwater fish, like pike, walleye, muskellunge, and bass, should only be eaten in moderation due to their potential mercury content.
Signs and Symptoms of Mercury Toxicity
Elemental mercury is a substance that, when absorbed by the body, can lead to several health problems. Breathing in mercury can cause symptoms like shortness of breath, coughing, fever, nausea, vomiting, diarrhea, headaches, a metallic taste in the mouth, excessive saliva and problems with vision. When these symptoms get really severe, they may result in trouble breathing, which can become life-threatening. When mercury is swallowed, it can change to inorganic mercury salts in the body, leading to the same set of symptoms.
Consuming organic mercury salts usually causes a metallic taste in the mouth and a greying of the inside of the mouth. In serious cases, it can lead to stomach pain, bloody inflammation of the stomach and intestines, damage to the tubes in the kidneys and shock. If the mercury salts are consumed over a longer period of time, they could cause a range of symptoms affecting the stomach, nervous system, and kidneys. These can include loss of teeth, excessive saliva, a burning feeling in the mouth, shaking, irritability, kidney disease, excessive proteins in urine, nervous exhaustion, and a painful condition affecting the hands and feet.
Organic mercury poisoning is mainly harmful to the nervous system and the damage can be permanent. The toxic symptoms usually appear weeks to months after being exposed. Early signs of this poisoning can include numbness or tingling around the mouth, headaches, shaking, and fatigue. In severe cases, it can lead to loss of coordination, blindness, abnormal body movements, and loss of memory. Besides these severe effects on the nervous system, patients may also experience mild problems with their kidneys, stomach, and breathing.
- Shortness of breath, cough, fever
- Nausea, vomiting, diarrhea
- Headaches, metallic taste in mouth, excessive saliva
- Vision problems
- Severe cases can result in respiratory distress
- Ingested mercury can cause same set of symptoms, and potentially stomach pain and shock
- Chronic ingestion can cause a range of symptoms including loss of teeth, shaking, irritability, and kidney issues
- Organic mercury toxicity primarily affects the nervous system
- Symptoms can occur weeks to months after exposure
- Severe cases can result in loss of coordination, blindness, abnormal body movements, and memory loss
Testing for Mercury Toxicity
If you are in the emergency department and there’s a possibility of mercury poisoning, the doctors will first take a detailed account of things like what you’ve been exposed to recently and the symptoms you’ve been experiencing. This is an essential part of figuring out if you’ve been affected by any of the health problems that come from mercury poisoning.
After that, you’ll likely undergo some initial tests. These could include a chest X-ray, a urinalysis (a simple test that checks different components of your urine), and some basic blood tests. One of these blood tests is the complete blood count which measures the cells that make up your blood, such as red blood cells. Another one is the metabolic panel, which checks how well your body’s metabolism is working by looking at your blood chemicals.
The doctors will also want to measure how much mercury is in your body. To do this, they can collect your urine for 24 hours and measure the mercury levels. For some forms of mercury exposure, doctors may also test the amount of mercury in your blood since these types don’t usually go out through your urine.
Having mercury in your urine or blood shows that you’ve been exposed to mercury, but it’s important to know that the amount of mercury found doesn’t directly tell how severe the poisoning is.
Treatment Options for Mercury Toxicity
If you find yourself in an emergency department due to mercury exposure, the first steps are to remove you from further exposure and clean any remaining mercury off your skin to prevent further absorption. Once you’re safe from ongoing exposure, the medical staff will start basic supportive care. This might include giving you oxygen and fluids directly into your veins (intravenous, or IV, fluids).
Next, the doctors will closely watch and manage any complications that arise from the mercury poisoning. This might include issues such as trouble breathing, bleeding in your digestive system, kidney failure, and even rupture of your intestines. You may also receive treatments like charcoal to try to bind the mercury in your stomach and intestines, even though this isn’t highly effective for removing mercury.
If you’ve been exposed to certain forms of mercury, you might be treated with medications that can bind the mercury and decrease its toxic effects, a process called chelation. One treatment option involves an initial injection of a medicine called dimercaprol, followed by an oral medication called succimer. It’s important to note that not all forms of mercury should be treated with these medications. For example, dimercaprol may actually worsen the effects of certain types of mercury on the nervous system.
There’s ongoing debate about whether it’s beneficial to use methods like dialysis (a treatment that filters your blood) in cases of mercury poisoning. This is mainly due to the fact that mercury tends to strongly bind to proteins in your body and spread throughout your tissues, which may limit the effectiveness of dialysis. However, if your kidneys have been damaged by the mercury, dialysis may be necessary to support their function.
A treatment called an exchange transfusion, in which your blood is replaced with donor blood or a blood substitute, has been considered. However, there’s currently no solid evidence that this improves outcomes in cases of mercury poisoning.
What else can Mercury Toxicity be?
Identifying mercury poisoning can be really challenging because the symptoms are quite common and can start at any time. These symptoms can often be mistaken for many other diseases that can affect various body parts, such as the kidneys, digestive system, nervous system, and lungs. That’s why doctors always make sure to have a thorough understanding of the patient’s health history. It’s important to consider other conditions that can cause similar problems, including:
- Alzheimer’s disease and other types of dementia
- Parkinson’s disease
- Stroke
- Cerebellar tumor (a type of brain tumor)
- Metabolic encephalopathy (a brain disorder)
- Digestive tract bleeding
- Ingestion of acid or alkali
- Iron, arsenic, or phosphorus poisoning
- Cerebral palsy
- Vertigo
- Amyotrophic lateral sclerosis (a nerve disease)
- Intrauterine hypoxia (oxygen shortage in the womb)
- Brainstem gliomas (a type of brain cancer)
- Carbon monoxide poisoning
- Alcohol or drug withdrawal
What to expect with Mercury Toxicity
The health impact of exposure to mercury greatly varies and depends heavily on how much mercury a person has been exposed to. If someone is exposed to large amounts of mercury, it could result in a coma or even death. However, minor symptoms may fade away over time. Nerve-related symptoms could take a while to show up, and might last for many years.
It’s important to note that fetuses and children are especially vulnerable to the effects of mercury exposure. This can lead to death or lasting damage to the nervous system. In severe cases, it could result in intellectual disability.
