Pathogenic microorganisms are organisms capable of producing disease. A Picocurie is a unit of radioactivity. A Curie is that quantity of any radioactive substance that undergoes 37 billion nuclear disintegrations per second. Thus a picocurie is that quantity of any radioactive substance that undergoes 0.037 nuclear disintegrations per second. Protozoa are microscopic animals that occur as single cells.
Some protozoa can cause disease in humans.
Protozoa form cysts, which are specialized cells like eggs that are very resistant to chlorine. Protozoa must be removed from drinking water by filtration, because they cannot be effectively killed by chlorine. Radiochemicals , or radioactive chemicals, occur in natural waters. Naturally radioactive ores are particularly common in the Southwestern United States, and some streams and wells can have dangerously high levels of radioactivity. Total alpha and beta radioactivity and isotopes of radium and strontium are the major tests performed for radiochemicals.