shapes and forms, but is increasing across the world. Improved industrialisation of poorer countries, increased consumerism, and greater pressures on world waste disposal services have all led to large amount of pollutants entering the oceans in a variety of ways.
Types of ocean pollution include:
- Oils from a number of sources, including oil spills, drilling leaks, and seepage from factories and vessels.
- Dumped trash. This is a big problem in poorer countries, where waste is either thrown into rivers or directly into the ocean.
- Sewage is often released untreated from coastal communities.
- Air pollutants can dissolve in the ocean and cause a number of problems, including ocean acidification.
- Agricultural runoffs like fertilizers and pesticides which can decimate sensitive marine populations¹.
How marine pollution affects human health
All of the world’s oceans contain huge amounts of plastic, ranging in size from microscopic beads to huge pieces of trash. Since plastic doesn’t biodegrade, it usually just keeps breaking up into smaller and smaller bits, eventually becoming microscopic sized pieces. As they are breaking up, plastics also release a number of deadly chemicals into the environment, some of which are easily absorbed by fish and shellfish².
Humans feel the effects of plastic pollution when they consume seafood. Tiny plastic beads are ingested by fish and marine mammals – intentionally or not – and make their way up the food chain. These plastics can contain heavy metals such as lead, mercury, and cadmium. Many also contain Diethylhexyl phthalate, an extremely toxic carcinogen. These and other toxins are often linked to cancer, birth defects, immune system problems, and childhood developmental issues².
Many other activities, especially around ports and other industrial areas, also have a direct impact on human health. Port activities can often result in the release of heavy metals and toxins directly into the ocean, where they are absorbed by the local sea-life. Filter feeding animals such as oysters and mussels simply feed on whatever they filter from the water, which unfortunately includes any toxins which are present. They can then store these toxins – often heavy metals – in quite high concentrations. This can cause problems if commercial fishing or aquaculture operations are happening in the same area, as harvested seafood may be contaminated. The toxins can then be passed on to humans, and have the potential to cause extremely damaging health problems and birth defects³.
Agricultural runoff and sewage dumping can lead to major algal blooms, which in turn can have terrible consequences on anyone who comes into contact with them. The high nutrient concentration in most agricultural runoff provides the perfect ingredients for algal blooms, which produce nasty toxins and lower the oxygen concentration of the water – particularly in protected areas such as bays and estuaries. People who go swimming or perform other water-related activities in the area can come into contact with these toxins, which can make them very sick or cause long-term problems. Seafood harvested from the affected area can also contain high concentrations of toxins, which can cause food poisoning if they are consumed. For this reason, certain fisheries are often closed when major algal blooms occur⁴.
It is obvious that human-induced marine pollution is not only harmful to the environment, but to humans themselves. It can cause the build-up of toxic pollutants in marine food-products, and even has the potential to make the ocean itself unsafe for us. In order to survive as a successful race, humans MUST do whatever it takes to reduce marine pollution.