What Is the Worst Type of Mercury?

A naturally occurring element in our environment, mercury is widely regarded as one of the most toxic heavy metals on Earth. Indeed, the World Health Organisation (WHO) has gone as far as to state that there is no level of exposure to mercury that can be deemed safe, underlining the seriousness of the health complications associated with this substance.

Nonetheless, it should be recognised that not all types of mercury are equally as dangerous as others. Although none can be considered benign, methylmercury – which is one of the most commonly occurring organic mercury compounds – is perhaps the worst from a human health perspective. This is due to its ability to bioaccumulate in the food chain, its ready absorption into the human bloodstream and its ease of navigation of both the blood-brain barrier (BBB) and the foetal placenta.

What is methylmercury?

Methylmercury is an organic mercury compound that is produced when mercury comes into contact and reacts with carbon. Most commonly, this occurs when microscopic bacteria ingest mercury and create methylmercury as a result. The substance can then infiltrate the food chain and bioaccumulate in larger animals, or else evaporate into the atmosphere and contaminate the air. After precipitation occurs, it can also pollute the soil.

If the latter occurs, it can jeopardise crop yields, while its presence in marine ecosystems can compromise the health of their inhabitants. From a human perspective, however, methylmercury is most concerning when it ends up on our dinner plates in the form of fish and other seafood.

Which foods contain the most methylmercury?

The most sophisticated modern techniques of monitoring for mercury have allowed us greater insight into which species of fish are more susceptible to absorbing and accumulating methylmercury in their bodies. Some of the most concerning species in terms of mercury concentrations include swordfish, shark, tilefish, king mackerel, bigeye tuna, marlin, orange roughy and Chilean seabass.

Of course, fish and seafoods are an excellent source of beneficial fatty amino acids such as Omega-3, as well as vitamin D, B12 and other nutrients that are important for a healthy body. As such, it’s not recommended to omit these foods from your diet entirely. However, you may wish to consider cutting down on the aforementioned species, perhaps by replacing them with alternatives that do not pose such a risk of mercury contamination, such as shrimp, salmon, oysters and scallops.

What are the effects of methylmercury exposure?

Consuming contaminated fish and seafood is the most common method of exposure to methylmercury, but it can also be inhaled in environments where the air is polluted or even absorbed through the skin. Even low levels of methylmercury can carry potentially disastrous health repercussions if exposure occurs over an extended period of time.

In less severe cases, methylmercury exposure can result in unpredictable mood swings, heightened anxiety or stress levels, numbness in the limbs or extremities, tremors and depression. In extreme cases, it can cause difficulties with breathing, impairment to both speech and vision, loss of motor skills, muscular fatigue and serious neurological complications. In the rarest situations, it can contribute to premature death.

If you’re eager to learn more about methylmercury in particular and other types of mercury in general, the upcoming International Conference on Mercury as a Global Pollutant (ICMGP) is an excellent opportunity to expand your knowledge. Scheduled for the 25^th to the 29^th July 2022, the event will take place virtually and is open to anyone with an interest in the subject.