Cadmium Mining and Heavy Metals in oil paint

I am an oil painter and the process of creating oil paint depends heavily on the color desired. To get many "earth tones" (Iron Oxide, Umber, Sienna, Ocher, etc.) or more muted colors, paint companies source these minerals from clay mines, where clay is often extracted for many different products (beauty products, industrial materials, making concrete, etc.). These kinds of mining processes can be harmful but also are extracted from sedimentary mines which means the minerals are created from soil runoff and refining through rivers and often don't require very deep mining to get these minerals. They often are just laying on the ground or make up the soil content of many areas. That is why pigments like iron oxide, umber, or ocher have been used as artistic pigments since the dawn of human history. 

Famous Yellow Ocher hills in Southern France

Rio Tinto in Spain (Iron Oxide leaking from the nearby hills into the river) 

These minerals don't have a  massive environmental impact if gathered/extracted correctly (and you can actually gather most of these minerals just off the ground here in California!). 

Ocher pigments I gathered near Death Valley, CA.

It is in the creation of the bright beautiful colors, that's where things get tricky... 

Cadmium is the element that creates Red, Orange, Yellow, and also Blue in traditional and professional oil paint. Cadmium is an element that needs to be mined deep from the earth, which requires a lot of heavy machinery and also produces a large amount of toxic runoff. This is often mined in tandem with zinc, or processed from raw Zinc. Cadmium is a heavy metal, and once unearthed can leak into the water table. These kinds of heavy metals like cadmium, lead, zinc, mercury, etc. also cannot leave the body once ingested and can pose long-term health threats if frequently exposed. 

The processing of raw cadmium into the bright colors we see in oil paint also requires heating under different conditions to produce the varied bright colors. This heating process also releases heavy metals and carbon into the atmosphere, which is dangerous to those exposed and the surrounding environment. 

Graphic on environmental/water pollution from heavy metal processing.

Cadmium Mine in Butt Montana, A.k.a. the Berkeley Pit.

Also! a good thing to note is because oil paint uses these heavy metals as primary colorants in most bright colors, always wear gloves when oil painting with these colors! Heavy metals build up in the body, and we all wanna be healthy happy artists when we're old.
There is a lot of research connecting historically famous and mentally unstable artists to heavy metal exposure through paint because we only recently have learned about the effect of heavy metals on the human body. Hatt makers used to use mercury in the glue when creating felt hats and would frequently have very high levels of heavy metals, which led to the phrase "mad as a hatter" which was popularized through the Mad Hatter character from Through the Lookingglass. Cadmium makes beautiful colors, but just be aware if it's bright and pretty you should probably wear gloves when painting with it!

Sources: https://observer.com/2016/10/toxic-art-is-anyone-sure-whats-in-a-tube-of-paint/

 https://serc.carleton.edu/NAGTWorkshops/health/case_studies/butte_case_stud.html

https://www.centralmaine.com/2013/09/20/researchers-look-at-maine-mine-contamination/