What liquid nitrogen does to your body?

Liquid nitrogen has a boiling temperature of -196°C at atmospheric pressure. Direct contact can freeze the skin causing frostbite and cold burns. Delicate tissue, such as eyes, can be damaged by an exposure to the cold gas alone which would be too brief to affect skin.

Explanation:

Liquid nitrogen vapor has the potential to instantly freeze skin tissues and inflict cold burns. If a person takes a small amount of it, liquid nitrogen in the stomach may expand. "As a result, major health problems or death occur," he says.

true, generally referred to as invasive species given that they have no natural predators in new environment

poor water quality affects most estuarine organisms, including commercially important fish and shellfish. the pollutants that have the greatest impact on the health of estuaries include toxic substances like chemicals and heavy metals, nutrient pollution (or eutrophication), and pathogens such as bacteria or viruses.