When copper sulfide is combined with chlorine dioxide to create a bleach, the reaction creates copper-chlorinated water.
In a 2013 study, researchers found that people who used this process to clean their toilets had elevated copper levels in their urine.
Copper poisoning can cause liver damage, muscle and joint damage, and kidney problems.
In the US, copper poisoning is most prevalent in those living in areas where the country has been hit by mining.
The problem is so common that people are still cleaning toilets and other plumbing facilities.
How to avoid it Copper poisoning is not the only problem caused by chlorine dioxide.
The National Health and Medical Research Council found that copper sulfides, a by-product of copper mining, can also cause liver and kidney damage in people who are exposed to low levels of the compound.
For example, a person who consumes up to 0.5 milligrams (mg) of copper sulfate per day may have a higher than normal risk of developing kidney damage, according to the NHRMC.
The copper sulfates are produced by copper mining companies in areas like copper mines and copper ore processing.
The NHRMRC said people with high copper intakes are more likely to have liver damage.
Copper sulfide-containing bleach can be purchased over-the-counter or as a solution in the form of water, according the NHP.
Copper oxide (CuO) bleach can also be purchased online or from home-based chemical manufacturers.
You can read more about copper poisoning on the NHC’s website.