Bioaccumulation

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Bioaccumulation is when chemicals build up inside a living thing over time because the organism takes in more than it can break down or shed. If a toxin stays in the body longer (has a long biological half-life), it can cause harm even if the environment isn’t heavily polluted. Organisms absorb chemicals through breathing, skin, or eating.

Bioconcentration means a chemical is more concentrated inside the organism than in its surroundings. Biomagnification means the chemical becomes more concentrated as it moves up the food chain, from plants and small animals to bigger animals and humans.

Some poisons dissolve in fats, so they accumulate in body fat. When fat is later burned for energy, these chemicals can be released and cause poisoning. Examples include methylmercury, DDT, and certain lead compounds. Heavy metals like mercury, lead, and cadmium can also build up, harming the brain, nerves, or reproduction.

Biotransformation, the body’s changes to chemicals, can increase or decrease how much toxin builds up. Some species use bioaccumulation for defense by storing toxins that deter predators.

Common examples and monitoring: mercury in fish, toxins from algal blooms that affect shellfish, and toxins in reef fish that cause illnesses in people. In ecosystems, pollution can travel up the food chain and affect wildlife and people who eat contaminated animals.

In short, bioaccumulation is the growing toxin load inside an organism, and biomagnification is the increasing level up the food chain.