That is complicated. The USA EPA (Environmental Protection Agency) is an amazing source of information. The problem is, there is so much information, it is hard

That is complicated. The USA EPA (Environmental Protection Agency) is an amazing source of information. The problem is, there is so much information, it is hard to learn anything simply. (I just tried a simple search, and it is overwhelming.) Of the four ingredients in BTEX, it may be easiest to start with Benzene. It is the 'heaviest', safest and perhaps simpler. (But do try to search for BTEX and EPA online, and you'll get to many interesting sites. Contaminated water, air, food, etc.) To simplify; Here is an example: https://wwwn.cdc.gov/TSP/ToxProfiles/ToxProfiles.aspx?id=40&tid=14 https://wwwn.cdc.gov/TSP/ToxProfiles/ToxProfiles.aspx?id=40&... I advise you to study without too much concern. As with a medical journal, if one starts reading about all the things that are bad for you, and surround you everywhere, it can be alarming. It is a fascinating field. Soil, water, and air chemistry are complex and interdependent systems, and when you throw in human, animal and plant toxicology, it is even more confounding. Unfortunately, the simplifications required for political battles, invested industrial lobbying, result in poor science.