Lead is one of the most dangerous chemicals known to man. It is used to make car batteries and some pigments. Lead is highly toxic and has been banned in paint products. Lead poisoning can cause nausea and vomiting and damages the brain. High levels of lead exposure can cause severe kidney damage as well as death

You may recognize acetone from nail polish remover, and may know that the fumes are extremely dangerous if inhaled. Acetone is also used for degreasing wool, and degumming silk. It is added to many e-liquids and Breathing in acetone can irritate the nose, throat, lungs, and eyes. It can also cause headaches, dizziness, confusion, a faster pulse, nausea, vomiting, effects on the blood, passing out and a possible coma.

Formaldehyde is one of the more dangerous but unknown chemicals. Formaldehyde is used by embalmers to preserve a corpse. This hazardous chemical can damage the lungs, skin, digestive system, and lining of the nose and throat. 

Toluene is also not very well known. Toluene is used as a solvent in paint thinners, nail polish remover, glues, and correction fluid. Toluene exposure can cause irritation in the eyes and nose, weakness, exhaustion, confusion, euphoria, dizziness, headaches, dilated pupils, lacrimation (discharge of tears), anxiety, muscle fatigue, insomnia, numbness or tingling of the skin, dermatitis, and liver and kidney damage. 

In the form of sand and clay, silicon is used to make concrete and bricks. It is a useful refractory material for high-temperature work, and in the form of silicates it is used in making enamels, pottery, etc. The FDA has warned that injected liquid silicone may move throughout the body and can cause serious health consequences, including death. Liquid silicone may block blood vessels in parts of the body like the brain, heart, lymph nodes, or lungs, leading to an extremely dangerous situation. ​

No,  not nickel as in the coin. Nickel is a detrimental chemical in  e-cigarettes that exposure to can cause reduced lung function, chronic bronchitis, and cancer of the lungs and nasal sinuses.

Benezene is majorly found in crude oil and gasoline. It is used to make plastics, resins, synthetic fibers, rubber lubricants, dyes, detergents, drugs, and pesticides.  It is naturally produced by volcanoes and forest fires. Consuming benzene in any way or form can cause vomiting, irritation of the stomach, dizziness, sleepiness, convulsions, rapid heart rate, coma, and even death. If you spill benzene on your skin, it can cause redness and sores.