All together, the article described severe pollution situations in 14 major rivers in India. Explaining types and levels of effects Reporting about toxic and hazardous chemicals is necessary, but it is not easy. Several things you might need to know include, first, the different effects chemicals can have on people. They can have a therapeutic effect , meaning that in a particular concentration the chemical is helpful. If we use aspirin as an example of a chemical, one or two aspirin tablets can take away a headache, having a therapeutic effect.
Chemicals also can have side-effects .
This means that at the same concentration that has a therapeutic effect, they can be harmful. For example, one or two aspirin tablets could have the side- effect of upsetting a person's stomach. Too much aspirin taken at once can cause people to spit up blood. Too much aspirin taken over a long period of time can cause stomach ulcers. A lethal effect is one that kills a person.