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WHAT IS BIOACCUMULATION AND WHY IS IT HARMFUL?
WHAT IS BIOACCUMULATION AND WHY IS IT HARMFUL?
by Jovan Tang
As an Environmental Systems and Societies (ESS) student, I have learnt many things that have deepened my understanding of how humans have impacted the world we live in, and one of the ways which we have done so is in the process of bioaccumulation of our waste material.
Bioaccumulation is the process in which toxins enter the food web by building up in individual organisms, accumulating in their tissues and being absorbed at a faster rate than the toxins can be eliminated or lost. Because these toxins are fat soluble, they tend to build up in fatty tissues. When humans release non-biodegradable waste such as plastics, mercury, or more, we speed up this process of bioaccumulation and all this toxic material builds up in animals and magnifies more and more as you move up the trophic levels of a food chain/web which might eventually work its way up to humans and our consumption - for example, microplastics.
Photo from WikiMedia Commons
Microplastics
According to the UN, an estimated 8 million pieces of plastic enter the ocean every day because of humans, and approximately 23 million tonnes of plastic waste enters the water every year. These larger pieces of plastic start breaking into smaller pieces but are never broken down fully because they are non-biodegradable. They eventually become so small that they are invisible to the naked human eye, and are therefore ‘microplastics’. But how is this related to bioaccumulation? In the oceans, millions of marine animals are exposed to and consume microplastics. Over time, they accumulate and work up the food chain eventually up to us humans.
Because of how much plastic we dump into the oceans, bioaccumulation occurs, and it results in the average person consuming between 78,00 and 211,00 microplastic particles yearly! Microplastics have even been reported to be found in breast milk.
However, we haven’t done enough research into this issue to truly know the impact the accumulation and consumption of microplastics has on us humans, and only time will truly be able to tell us the true extent of the effects of microplastics. However, a bioaccumulation event which had direct observable effects on humans happened - in the Minamata fishing city in the 1950s.
Mercury in Minamata
Have you ever heard of the phrase ‘Mad as a Hatter’? This term was based on the 19th-century English hat makers who inhaled mercury vapours in the hat-making process which led to them becoming ‘mad’ - muscle tremors, distorted speech, and hallucinations. In the seaside city of Minamata in Japan, almost the entire population went ‘mad as a hatter’ because of bioaccumulation.
A local petrochemical and plastics company, Chisso Corporation, dumped an estimated 27 tons of methylmercury into Minamata Bay over 37 years. Bioaccumulation of this mercury occurred, and high contamination levels in the people of Minamata led to severe neurological damage which directly killed more than 900 and left an estimated 2 million people with long-term health problems or permanent disabilities. This impact extended to local wildlife as well as local cats were seen acting strangely before collapsing and birds falling from the sky. By 1977, Japan’s government had started cleaning the mercury sediments in the bay and over the course of about 20 years vacuumed up 1.5 million cubic metres of contaminated sludge.
Photo from Disney
Photo from Fox News
Conclusion
So, in conclusion, we as humans need to realise the devastating impact of just dumping away waste we don’t want to deal with. Even if there isn’t an immediate direct impact, over time, the process of bioaccumulation occurs and comes back to harm not only humans but entire ecosystems. While it is good that governments and researchers have done a lot to try to mitigate the impact of our waste and clean up toxic material that could bioaccumulate, we need to do more to prevent that waste from entering ecosystems to be able to bioaccumulate in the first place, and this can only be done with stricter regulations and more research into long term sustainable waste disposal methods.
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