Natural gas is a byproduct of oil recovery.
In addition, most air ionizers produce ozone as a byproduct.
Bilirubin is a natural byproduct of the breakdown of red blood cells, however, a high level of bilirubin may indicate a problem with the liver.
Emotional damage to a child is also often the byproduct of child abuse, which can result in the child exhibiting serious behavioral problems such as substance abuse or the physical abuse of others.
Food poisoning symptoms occur when food-borne bacteria release toxins or poisons as a byproduct of their growth in the body.