WHAT? As said in my previous post, Bio-accumulation is the gradual accumulation of harmful substances, such as pesticides, or other chemicals in an organism.
HOW? One way is by an amount of the chemical coming into the living organism faster than the organism can break it down and use it. To put it simply, there is more input than output, therefore causing the chemical to accumulate in the organism.
The other main way is by the chemical coming into the living organism and the organism not being able to break it down or excrete it in any way whatsoever. Ergo, the chemical continues to accumulate until it eventually becomes deadly to the living organism.
Here are some examples of how this would occur: Let’s take car emissions – they are a huge contributory factor as they release chemicals into the air. Now picture these building up in trees and birds. Upon raining, these chemicals would then get washed out of the air and seep into the ground where they would certainly enter plants and the animals which eat these plants.
Another example is illustrated below and in water:
As humans, we sit at the top of the food chain, and those droplets of toxins in plankton/krill can be quite substantial by the time we ingest they get to us through the links in the food chain.
WHAT? Also known as bio-amplification/biological magnification, Bio-magnification is a cumulative increase in the concentrations of a persistent substance (e.g. pesticides, metals, etc.) as it moves up the food chain.
The below drawing nicely illustrates what this is, with mercury being the heavy metal
HOW? Bio-accumulation occurs at the base of a food web, usually within primary producers like phytoplankton. These microscopic organisms absorb POPs or Persistent Organic Pollutants like DDT ( an insecticide) or PCBs (flame retardants) directly from the seawater and accumulate them in their bodies over time. The toxins build up in their tissues because they are absorbed from the water at a rate faster than they can be metabolized. Bio-magnification then occurs when slightly larger organisms called zooplankton feed upon the contaminated phytoplankton and in turn absorb POPs into their own tissues at a higher concentration. The POPs can be passed from producer to consumer (to consumer, to consumer, and so on…) Bio-magnification can continue all the way up the food web or chain. Because the amounts of POPs become more and more concentrated at each link in the food chain, some of the ocean’s apex predators are at risk of gaining potentially fatal levels of POPs within their bodies, like orcas for example.
Now consider this: All the toxins we ingest through our foods bio accumulate in our bodies and as apex predators, these toxins are bio-magnified through the food chain. To top it, we live in increasingly polluted cities and use products with known and unknown chemicals on our bodies ( soaps, shampoos, moisturizers, toothpastes, perfumes, makeup etc, in our homes ( detergents, air fresheners, anti-dust sprays, sprays to polish and clean furniture etc), in our offices ( sprays to clean surfaces, floor cleaners, air fresheners etc) far from nature in concrete jungles …is it any surprise that we are increasingly sick, depressed and unhappy?
So, I feel one should reasonably avoid as many chemicals as possible and try to simplify life by making careful, sustainable choices which work out not just for us as individuals but us as a society. And in the long run, it will work out for your pocket too!