One of the greatest advances in human technology, ever really, is the invention and production of plastics. The wide variety of plastics has ensured that their is a plastic for just about every purpose imaginable; quite simply, plastic is unmatched by all other man-made materials for its combination of adaptability, durability, low cost, and ease of supply. It is therefore perfectly understandable that, despite the following reasons why this material isn’t necessarily a good thing, people use it regularly for a wide array of purposes.
To understand why plastic isn’t good for human health, and specifically why its uncontrolled proliferation throughout the world, through the form of trash/litter, is a particular risk, you need to also understand some of the general problems of plastic:
If you understand these points, then you should be able to understand how plastic presents a risk to human health; the extraction and production of plastic can potentially cause damage to the environment, which has indirect and direct repercussions on human health, and the end result, the plastic, is difficult to contain and manage, and once it has spread throughout the environment, the plastic’s toxicity can harm humans and the wider food chain.
Because plastic isn’t biodegradable, once it has entered the environment, it becomes very difficult to remove it. One of the problems which exacerbates this is that although plastic doesn’t biodegrade, it can erode into smaller and smaller sizes, which means that these microscopic bits of toxic plastic can be easily consumed by animals, and once that has happened it has entered the food chain and it becomes very difficult to do anything at that point to mitigate its continued proliferation in the environment.