Terrestrial and Aquatic Pathways

Contamination of land and water can occur from deposition of waste material originally introduced into the atmosphere, from discharge directly into surface or subsurface waters, or from wastes placed in or on the ground. Ground contaminants may eventually be mobilized by groundwater or erosion. The primary reason for being concerned about radioactive contamination of the environment is that it may result in the exposure of humans. The two major reasons for focusing concern on humans have to do with human values and the relative radio resistance of many plants and lower animals. It has been generally assumed that if one protects one's own environment sufficiently to protect oneself, then natural systems would automatically be protected. The known effects of radiation on aquatic and terrestrial species, populations, and ecosystems are reviewed. Most national and international authorities recommend that environmental radiation doses to humans in the general population from facilities should be limited to a maximum of 1 mSv (100 mrem) per year. Using this value as a starting point, models were examined as likely doses to plants and animals in natural systems. It was found that the doses to natural organisms were unlikely to exceed 1 mGy (100 mrem) per day under the prevailing radiation protection standards. The model calculations were conservative; therefore, the actual doses to natural species are likely to be a factor of 10 or 100 smaller. The current level of protection afforded to humans from routine radioactivity releases appears to be adequate to protect other species as well.