Soil metal concentrations were found to be high enough to potentially contaminate groundwater. In addition to killing fish, the toxic algae contaminate shellfish. Spilled oil can also contaminate drinking water supplies. Leaks from underground tanks and abandoned refineries may also contaminate groundwater in surrounding areas. Also, because of the subsurface detonation, radioactive debris may contaminate the local groundwater. Indirectly, communities are exposed to wildfire debris that can contaminate soil and water supplies. Officials said the leak did not contaminate groundwater. Salmonella can also spread to humans when turtles contaminate drinking water. If this is not contained it can contaminate groundwater. Food microbiology is the study of the microorganisms that inhibit, create, or contaminate food. Besides the foul smell, human waste can contaminate local water systems and spread disease. Fallout and black rain may contaminate waterways, agriculture, and soil. Charcoal briquettes contain many additives that can contaminate the flavor. In her view, the foreground creates a world of poisons that contaminate natural life. The icy film and sweat residue may contaminate sensitive surfaces and affect optical performance.