Related by context. Frequent words. (Click for all words.) 71 perchlorate 54 Nitrates 53 Nitrate 53 contaminate groundwater 51 Arsenic 50 Fluoride 49 Contaminants 49 Tritium 49 Cadmium 49 trichlorethylene 49 contaminant 48 Pollutants 48 Plutonium 48 Sulfur dioxide 48 nitrates 47 Phthalates 47 tritium 47 Atrazine 47 contaminate drinking 47 Contamination 47 carcinogen 47 occurs naturally 47 groundwater 47 Groundwater 47 chloride 47 contaminants 46 Dioxins 46 endocrine disruptors 46 trihalomethanes 46 methyl mercury 46 arsenic 46 Toxins 46 Contaminated 46 Pesticides 46 perchlorethylene 46 trace amounts 45 PBDE 45 #,# dioxane 45 human carcinogen 45 oxidizer 45 PFOS 45 methylmercury 45 Melamine 45 nitrate 45 groundwater contamination 45 Sodium 44 triclosan 44 neurotoxin 44 Calcium 44 naturally occurring 44 PAHs 44 Iodine 44 hydrazine 44 polychlorinated biphenyls PCBs 44 Elevated levels 43 Benzene 43 chromium 43 Safe Drinking Water 43 hexavalent chromium 43 radioactive tritium 43 Phosphorus 43 radionuclides 43 Radiation 43 Fluoridation 43 Bacteria 42 fecal bacteria 42 Chlorine 42 Bisphenol 42 toxic chemicals 42 selenium 42 oxidant 42 colorless odorless 42 Sediment 42 iodine 42 Toxic Substances Control 42 phosphorus 42 thyroid function 42 pollutant 42 silicates 42 fecal coliform bacteria 42 groundwater pumping 42 Dioxin 41 PCB contamination 41 carcinogenic 41 E. coli bacteria 41 contaminated 41 Ricin 41 Cryptosporidium 41 naphthalene 41 organic compounds 41 PBDEs 41 strontium 41 Radioactivity 41 Pollution 41 Toxic Substances 41 Toxicity 41 carcinogens 41 PFOA 41 underground aquifer 41 Concentrations 41 fire retardants