In Camelford there where 20 tones of aluminum in the water. It was poured in the wrong tank at the local treatment plant and cause stomach cramps,rashes and aching joints
Humans do things like liter and that litter ends up in the lakes and the oceans. We dump waste in the oven because we think it is easier to get rid of and we are not being conscious enough to find other way to get rid of waste
Some people organize clean up groups to pick up trash and that keeps the trash from landing in the oceans. A specific group is SERVPRO. They are a cleaning group.
Humans try to find different ways to get rid of waste. They try to find different places to put it. Also they are more careful on what they flush down the toilet like not flushing down chemicals and stuff because some of that goes in the oceans.