Yes
Mendelevium is a radioactive element. Generally radioactive elements are dangerous.
The planet Mercury is way to close to the sun. Plants, humans, and all other organisms would be incinerated by the heat of the sun.
Cicadas are not dangerous nor harmful to humans however they are very noisy and tend to eat certain plants.
No, but they are a real pest of plants.
Yes, there are a number of plants that are toxic if ingested and also animals that can be dangerous to humans.
Plants can be dangerous to humans due to poisons or allergies.
No tehy are not to humans but they eat plants at fast rates
Earwigs are not dangerous, but they can be a pest, eating plants and fruits. Their pincers are too small to pose any danger to humans.
No, There is no carnivorous plants we know of that are dangerous to humans. Their liquid is just enzymes of preservatives and other things. I have a nepenthes Ventricosa x Boschiana, flytraps, Sarracenias, and sundews.
There are many, but two are: Waste water run off from factories and manufacturing plants, and humans.
power plants fueled by fossil fuels
There are poisonous plants and carnivorous plants