Related by context. Frequent words. (Click for all words.) 63 toxic chemicals 59 pollutants 58 mercury emissions 58 cadmium 57 arsenic 57 toxic substances 57 toxins 55 PCBs 54 chromium 54 contaminant 54 fluoride 54 pollutant 54 contaminants 53 nitrate 52 sulfur dioxide 51 iodine 51 hazardous chemicals 51 BPA 51 particulate matter 51 air pollution 51 nitrates 50 benzene 50 dioxin 50 radioactive iodine 50 radioactivity 50 sodium 50 cesium 50 radioactive material 50 phthalates 50 perchlorate 49 pollution 49 ozone 49 carbon dioxide 48 carcinogens 48 phosphorus 48 particulates 48 temperatures 48 chlorine 48 toxin 48 selenium 48 temperature 47 phosphorous 47 greenhouse gases 47 radiation 47 trace amounts 47 carbon monoxide 46 hazardous waste 46 radioactive 46 manganese 46 ash 46 micrograms 45 carcinogen 45 ppb 45 groundwater 45 formaldehyde 45 zinc 45 volatile organic compounds 45 toxic 44 radon 44 smog 44 potentially harmful 44 chemicals 44 radioactive materials 44 soot 43 thermometers 43 hazardous substances 43 CO2 43 ammonia 43 cyanide 43 pesticide 43 pesticides 43 methane 43 carbon dioxide emissions 43 carcinogenic 42 acid rain 42 ppm 42 Environmental Protection Agency 42 depleted uranium 42 degrees Celsius 42 vitamin D 41 gases 41 degrees Fahrenheit 41 radioactive waste 41 contamination 41 hazardous 41 greenhouse gas 41 EPA 41 concentrations 41 emissions 41 greenhouse gas emissions 40 degree Celsius 40 Radiation 40 coal ash 40 Pollution 40 CFLs 40 sulfur 40 polluted 40 toxic waste 40 solvents 40 methane gas 39 emission