Marine pollution and health effects

MARINE POLLUTION

Marine pollution is a combination of chemicals and trash, most of which comes from land sources and is washed or blown into the ocean. This pollution results in damage to the environment, the health of all organisms, and economic structures worldwide. 

Multiple Pollutants, Multiple Health Effects

Ocean pollution is a complex mixture made up of mercury, plastic waste, manufactured chemicals, petroleum wastes, agricultural runoff, and biological threats, like harmful algal blooms. People are exposed to these toxins mainly by eating contaminated seafood.

Coal combustion is the major source of mercury pollution in the oceans. When coal is burned, mercury enters the atmosphere and eventually washes down into the sea. The authors noted that when a pregnant woman eats mercury-contaminated fish, the mercury can damage her child’s developing brain resulting in IQ loss and behavior problems. In adults, consumption of mercury-contaminated fish increases the risk for heart disease and dementia.

Plastic waste makes up an estimated 80% of marine pollution. About 10 million metric tons of plastic waste enter the oceans each year, killing seabirds, fish, and marine mammals. It breaks down into smaller pieces called microplastics that absorb a range of chemicals floating in the marine environment, including pesticides and toxic metals. These chemical-laden particles are ingested by fish and shellfish and then passed on to seafood consuming humans. Microplastics may harm marine and human health, but the risks are still largely unknown.

“There's a lot of work needed to better understand the composition, toxicity, and potential human health impacts of microplastics, but it’s likely that it’s pretty substantial,” said Landrigan.

The chemicals used to manufacture a range of products, from consumer goods and food packaging to cleaning products and pesticides, also end up in the seas. The authors wrote that of the thousands of manufactured chemicals and chemical mixtures that pollute the world’s oceans, humans are most likely to be exposed to polychlorinated biphenyls, dioxins, brominated flame retardants, perfluorinated substances, and pesticides by eating contaminated seafood. These chemicals have been shown to cause a wide range of health effects in humans such as cardiovascular disease, developmental and neurobehavioral disorders, metabolic disease, immune dysfunction, endocrine disruption, and cancers.

Algae are essential components of aquatic food webs and ecosystems. But too much of a good thing can be toxic. Harmful algal blooms (HAB) occur when toxin-producing algae grow excessively in ocean waters. Warming sea waters make formerly unsuitable habitats habitable, leading to a range expansion of HAB species and the human populations they affect. Industrial waste, agricultural runoff, pesticides, and human sewage can all spur a HAB event. People are exposed to HAB toxins from eating contaminated fish and shellfish. These toxins can cause dementia, amnesia, other neurological damage, and death.

Solutions for marine pollution include prevention and cleanup. Disposable and single-use plastic is abundantly used in today’s society, from shopping bags to shipping packaging to plastic bottles. Changing society’s approach to plastic use will be a long and economically challenging process. Cleanup, in contrast, may be impossible for some items. 

-Shivam Kumar