The snowball effect. This is a concept most of us are quite familiar with: you have your second drink then suddenly you’re on the floor of the taxi home; you slowly start to age then before you know it you’re a quarter of a century old; or, you push a snowball down a hill and it gradually increases in size. You get the idea. The reason behind painting such a vivid picture, is so that I can introduce the topic of bioaccumulation, which does pretty much what it says on the tin.
Let me break it down for you
Bioaccumulation is “defined as [the] uptake, storage, and accumulation of organic and inorganic contaminants by organisms from their environment”, i.e the accumulation of things that aren’t a natural part of the organism’s ecosystem. Some examples of contaminants are pesticides, plastics or other non-biological chemicals; as all of these are a result of human activity, it’s interesting that we call other animals pests. The build up of these contaminants occurs when the organism can either not break them down fast enough while continuing to consume them, or they can’t break them down at all in the first place.
Food chains and food packaging
One example of bioaccumulation is with mercury in water based ecosystems. The proposed mechanism is that bacteria will ingest mercury that enters the water as a pollutant, which then moves up the food chain to larger fish, aquatic birds and land animals such as bears (including the kind you’ll find in Berlin) who feed on the fish. As it moves up the food chain, it also increases in concentration due to another effect called biomagnification. In addition to mercury, plastics and pesticides also end up in the food chain through basically the same mechanism.
Polycarbonate Bisphenol A (BPA) is one of these plastics. It is used frequently in food packaging and you can find it in practically any store. In a process called leaching, the BPA can actually enter the products it is containing. For example, it was found to “migrate from polycarbonate water bottles [into the water] at rates ranging from 0.20 to 0.79 ng[nanograms] per hour”.
Is it a problem?
BPA in particular has generated quite a lot of controversy as it has been shown to “interact with estrogen receptors” resulting in adverse health effects such as “female and male infertility, precocious puberty, hormone dependent tumours such as breast and prostate cancer and several metabolic disorders including polycystic ovary syndrome”. BPA has also been shown to lead to obesity in several different species, including humans. Given that it has been shown to lead to such problems, I wonder if people will be as angry about the migration of BPA as they are about other types of migration. The reason that BPA can have these effects is because BPA and estrogen have similar chemical structures – kind of like identical twins with marginally different hairstyles – allowing BPA to cause changes to the hormonal system in humans. Essentially, yes it is a problem to consume BPA, though there are still debates on the ‘safe levels of exposure’.
While there are several arguments against the consumption of seafood – particularly ethical ones – mercury poisoning isn’t a big danger for the average eater, though it goes without saying that in this case, what doesn’t kill you probably isn’t making you any stronger.
The new global phenomenon
The obvious way to avoid the negative effects of bioaccumulation would be to eat products which are relatively low in the food chain – for example plants or insects – as the effect of biomagnification will not be realised at this level. However, this is merely an evasive method and it doesn’t deal with the actual root causes. Plastic contamination is also such a widespread issue that Prof Rolf Halden – a noted expert in determining where in the environment mass-produced chemicals wind up – said “plastic exposure is a global phenomenon, and finding unexposed subjects for comparison is nearly impossible” when commenting on the long term effects, as right now they are not really well known. This basically shows how our excessive use of plastics, in tandem with our carelessness and unwillingness to tidy up after ourselves, leads to contamination in the environment, even in communities which don’t heavily use plastics.
From all of this, it can be seen that our irresponsibility to protect the environment, is not only resulting in the deaths of several species, but it is also coming back to haunt our own. It’s important to become more aware of how we are all responsible for everything involved in the products we buy, including the pollution to produce it, and where it eventually ends up after we discard it. While it is true that BPA replacements have the potential to be just as toxic, that does not excuse the problems it itself can cause. The best solution is to educate people on reduced consumption and move to a system where there is less need for plastics with such properties. Though of course education is a slow process and behaviour change doesn’t just happen overnight. From now on, just try to be more aware of what you put in your body: research, rethink and recycle.
Jack McGovan is a recent graduate in chemistry with a specialisation in ‘Energy and Sustainable Chemistry’ from the University of Groningen, the Netherlands. Following a job as a student journalist covering the energy transition, he has moved to Berlin where he is following his passion for working towards creating a fairer and more sustainable world. Seeing a gap in the way in which the world of science was communicated, he founded Delta-S. By writing source based content, he hopes to communicate his findings to a wider audience.