ANTIBIOTIC SUSCEPTIBILITY TESTING. Bacteria demonstrate two kinds of resistance to antibiotics, namely intrinsic resistance and acquired resistance. Intrinsic resistance means that the species was resistant to an antibiotic even before its introduction.
Radiation is naturally present in our environment, as it has been since before the birth of this planet. In addition, radiation can be produced artificially, as in medical x-rays and microwaves for cooking. Nonetheless, most people are not aware of all the natural and man-made sources of radiation in our environment.
Emissions of Mercury into the Air. Mercury becomes a problem for the environment when it it is released from rock and ends up in the atmosphere and in water. These releases can happen naturally. Both volcanoes and forest fires send mercury into the atmosphere.