For years, the element mercury was a part of many everyday items. Light bulbs, paint, thermometers, and batteries used the substance. It even found its way into medicine used for cuts, scraps, and burns. Then, scientists realized that mercury could be harmful.

Mercury is a natural metal. It is present in rock, soil, and water. Pollution from coal-burning power plants sends mercury into the atmosphere. In the air, mercury molecules can travel thousands of miles. Eventually, most land in water. In the ocean, bacteria attach to the mercury. This new form of mercury is called methylmercury. It is poisonous. Most ocean fish will contain some mercury.

Here’s why: Microscopic marine algae called phytoplankton absorb methylmercury from ocean water. Tiny marine animals gobble up phytoplankton. That means those marine animals ingest the methylmercury too. Small fish scoop up the little marine animals. Uh oh! Now the small fish have methylmercury in their systems. Larger fish eat the small ones. At the same time, the big fish are slurping up their own share of methylmercury.

Larger fish usually carry greater amounts of mercury. Why? Many live a long time. They eat and store mercury in their bodies all along. Scientists study mercury toxicity (how poisonous something is) in the goliath grouper. These fish live close to ocean shores where pollution can contaminate water. Goliath grouper live for decades—enough time to accumulate a load of mercury.

In the 1950s, factory workers dumped mercury into Japan’s Minamata Bay. People who ate fish from the bay got very, very sick. Mercury poisoned around 2,000 people! In 1972, 6,500 people in Iraq suffered poisoning after eating mercury-contaminated bread.

Mercury damages human nerves. Mercury poisoning causes memory loss, muscle weakness, numbness, and rashes. Some symptoms become very serious.

God made mercury for a good purpose—but that does not include eating it. Scientists have done a good job of educating people about the danger of too much mercury. God puts people in our lives to keep us safe from dangerous things. Proverbs 10:17 says, “Whoever heeds instruction is on the path to life.”