There are so many chemical agents that we use or are exposed to in everyday life that it is hard to know where to start!
A very common chemical agent is nicotine, which is found in cigarettes and e-cigarettes (commonly known as vapes). Nicotine is legal in the United States, but it has many detrimental effects on the human body, including addiction, nausea, diarrhea, increase in blood pressure, and increase in pulse rate, just to name a few. The legality of cigarettes and other inhalants containing nicotine makes it far more accessible to the general public than ordinary chemical agents and therefore more deadly on a larger scale.
Another chemical agent we are confronted with on a daily basis is carbon monoxide, which is emitted in exhaust from cars and other vehicles. Small amounts of carbon monoxide are also released from some appliances or small motors. People can have multiple symptoms from exposure or none at all. The most common symptoms are dizziness, nausea, upset stomach, or headache. Because we are around this chemical agent on a daily basis, we may not even notice its effects.
It is important for us to examine all of the chemicals we are exposed to on a daily basis because many of them lead to sickness or even death if we are exposed to them over a long enough period or on a large enough scale. I have posted links to the CDC (Centers for Disease Control) website if you would like to look at other commonly used chemical agents. When we examine our everyday lives and think about both the food and drink we ingest and the chemical agents we are exposed to, we are able to keep our bodies healthy with the choices we make. Hope this helps!