The salt in seawater dehydrates your body. (That's why meat could be preserved with salt.)
Swimming in the ocean for long periods can lead to dehydration primarily due to the high salt content of seawater. When you swim, you may not realize how much water you lose through sweat and breathing, and the salt in the ocean can increase your thirst, making you less likely to hydrate properly. Additionally, you may not feel the effects of dehydration as acutely while in the water, leading to a delay in recognizing the need for fluid intake. As a result, prolonged exposure can deplete your body's hydration levels.
2 weeks
it can be blast
Staying in front of a heater for too long can lead to dry skin, dehydration, and discomfort. Prolonged exposure to high temperatures can also increase the risk of heat-related illnesses such as heat exhaustion or heatstroke.
salt content of the water
3 days
Hyperthermia can be caused by prolonged exposure to high temperatures, strenuous physical activity, or by certain medical conditions such as heat stroke or thyroid disorders. It can also be a side effect of certain medications or substances.
Not likely. Only a long history of insufflating the powder could potentially cause sufficient inflammation for cancer to even be a possibility. The preservatives are probably more likely induce cancer, but again, only over long-term repeated and significant exposure. Don't fret.
Excessive use of tanning booths as well as prolonged exposure to the sun has been shown to induce premature ageing in peoples skin.
Fjord
Mercury can stay in the brain for a long time after exposure, potentially for months to years, depending on the level of exposure and individual factors.
Kidney stones.