If you read the news regularly, you will know that journalists love talking about how x, y and z chemicals are bad for humans and/or the environment. These articles talk about how pollutants affect a species’ survival, growth, development, fertility, etc. But how exactly does a pollutant do this? What special powers does it have to cause these broad and harmful changes?
Pollutants have three special powers: the powers to bind, accumulate and interact.
Pollutants can harm us by binding to things in our body. They can bind to molecules on the surface of our cells and disrupt communication between cells. If our brain and body don’t listen to each other, we will be unable to function normally. Pollutants can also bind to our enzymes and prevent them from carrying out essential activities like digestion, metabolism, etc. And they can bind to DNA and change the amount of proteins that are produced. Right amounts of proteins are needed to build cells, produce hormones and maintain immunity.
Pollutants can accumulate within the organs of our body. This can cause our organs to become poisoned if the cells in the organs breakdown from the continuous stress of removing pollutants. Also, the pollutants can directly interfere with an organ’s functioning. And if radioactive pollutants accumulate, they can alter DNA and cause cancer.
If there are two or more pollutants in an organism, they can interact with one another. Mostly the combined effects of the pollutant will be equal to the sum of their individual effects (1 + 2 = 3). Sometimes however, their combined effect can be greater than the sum of their individual effects (1 + 2 = 5). This can happen if pollutant A increases the activity of pollutant B. But their combined effect can also be less than the sum of their individual effects (1 + 2 = 1). This occurs if pollutant A hinders the activity of pollutant B.
How we fight back
So how do we fight back against these special powers that harm us? Well, we can create molecules that attach to the pollutant and prevent the pollutant from binding to cells, enzymes or DNA. Or we can hide it away in a globule of fat. We can also break down the pollutant and make it less toxic. And of course, we can excrete it out.
If these mechanisms don’t kick in on time, we also have the ability to repair the damage caused by pollutants.
Principles of Ecotoxicology (4th Edition) by C.H. Walker, R.M. Sibly, S.P. Hopkin and D.B. Peakall