Correlation vs. Causation

There are so many different studies referenced on this site. Many of them demonstrate a correlation between higher levels of heavy metals and increase/worsening of chronic diseases. Some studies even demonstrate a causal relationship. 

CORRELATION VS. CAUSATION​
Correlation is a relationship between two variables, and causation occurs when one of those variables has an effect on the other. A common mistake reporters make when writing about medical studies is confusing correlation and causation. Two variables in a study can be related without one actually being directly caused by the other.
​“Correlation vs. Causation.” Association of Health Care Journalists, healthjournalism.org/glossary-terms/correlation-vs-causation/.