**Non-Biodegradable Pollutants**

Non-biodegradable pollutants are substances that cannot be broken down or decomposed by natural processes, such as bacteria or other microorganisms. These pollutants persist in the environment for a long time and can have harmful effects on ecosystems and human health. Three examples of non-biodegradable pollutants are:

1. DDT: DDT, or dichlorodiphenyltrichloroethane, is a synthetic insecticide that was widely used in the past to control pests such as mosquitoes and agricultural pests. DDT is highly persistent in the environment and has been found to accumulate in the fatty tissues of animals. It can biomagnify through the food chain, leading to higher concentrations in predators such as birds and fish. DDT has been linked to negative impacts on wildlife, including thinning of eggshells in birds, which can result in reduced reproductive success.

2. Salts of heavy metals: Heavy metals such as lead, mercury, cadmium, and chromium are examples of pollutants that do not degrade easily. These metals can enter the environment through various sources, including industrial activities, mining, and improper waste disposal. Once released into the environment, they can persist for a long time and have toxic effects on both ecosystems and human health. Heavy metals can accumulate in the soil, water, and organisms, leading to contamination of food webs and potential health risks.

3. Radioactive substances: Radioactive substances, such as uranium, plutonium, and radioactive isotopes of elements like iodine and cesium, are another example of non-biodegradable pollutants. These substances emit ionizing radiation, which can have harmful effects on living organisms. Radioactive pollutants can persist in the environment for thousands or even millions of years, depending on their half-life. Improper disposal of radioactive waste or accidents at nuclear power plants can result in the release of these substances into the environment, posing significant risks to ecosystems and human health.

**Conclusion**

In conclusion, all three pollutants mentioned in the statement – DDT, salts of heavy metals, and radioactive substances – are non-biodegradable. They persist in the environment for extended periods, accumulate in organisms, and can have adverse effects on ecosystems and human health. It is important to minimize the release of these pollutants into the environment and properly manage their disposal to prevent further environmental degradation.