| Contaminant | MCLG (mg/L) | MCL or TT (mg/L) | Potential Health Effects from Ingestion of Water | Sources of Contamination in Drinking Water |
| Alpha particles | Zero | 15 picocuries per Liter (pCi/L) | Increased risk of cancer | Erosion of natural deposits of certain minerals that are radioactive and may emit a form of radiation known as alpha radiation |
| Beta particles and photon emitters | Zero | 4 millirems per year | Increased risk of cancer | Decay of natural and man-made deposits of certain minerals that are radioactive and may emit forms of radiation known as photons and beta radiation |
| Radium 226 and Radium 228 (combined) | Zero | 5 pCi/L | Increased risk of cancer | Erosion of natural deposits |
| Uranium | Zero | 30 ug/L (as of 12/08/03) | Increased risk of cancer, kidney toxicity | Erosion of natural deposits |