Have you ever heard of the Agency for Toxic Substances and Disease Registry? If not, the name tells you a lot. It is the government agency that determines the health risks of being exposed to harmful substances. They have a National Priority List that actually ranks the most harmful substances. Any guess what number one is?

If you read the title, you know, Arsenic! We’ve all seen movies or heard jokes about someone slipping this nasty stuff into someone’s food to get them “out of the picture,” but what exactly is it and what does it do?

Arsenic is a naturally occurring element whose name comes from the Latin word arsenicium, meaning masculine. Mining by the ancient Greeks, Egyptians and Chinese made knowledge of its poisonous form well known, even thousands of years ago. Typically obtained from the mineral arsenopyrite, it’s used in bronzing, fires, bullet making, transistors and other electronics. PubChem classifies arsenic as an acute toxicant and an environmental hazard, and the International Agency for Cancer Research labels it as Group 1, or carcinogenic to humans. Even before something long term like cancer happens, it can be acutely problematic by causing gastrointestinal symptoms, skin discoloration, neurological dysfunction and even developmental problems in kids.

Arsenic is specifically concerning to humans because it has been associated with lung, bladder and kidney cancers. A not-so-fun fact that I have to know for my medical boards: What is the number one cause of squamous cell skin cancer over areas that were NOT sun exposed? The title once again tells us the answer!

What is important to remember is that everything harmful I have just said about arsenic is from it inorganic forms, such as arsenate and arsenite. Organic arsenics are found naturally in seafood and the soil, and while they don’t cause any harm, they also have no nutritional value.

Without getting into too many nitty gritty details, inorganic arsenic poisons people by binding to sulfhydryl and thiol groups on proteins throughout the body. This makes the proteins stop working, and important processes such as cellular respiration (energy production and metabolism) can’t be done. It can also lead to hemolysis (red blood cells bursting).

Inorganic arsenic can be ingested, and while drinking water contamination has been reported in Bangladesh, India, Taiwan and Mexico, we don’t have to look far from home to see some of its effects on populations.

The Strong Heart Family Study, which is “the largest epidemiologic study of cardiovascular disease in American Indians” has produced several publications suggesting that arsenic in Indigenous communities has been linked to greater rates of type 2 diabetes, hypertension, overall cardiovascular mortality, overall cancer mortality and all-cause mortality.

This is especially concerning when you pair this with the fact that the U.S. government has, at times, performed poorly in monitoring for arsenic. For example, in Arizona, a state where the average drinking water level of arsenic is above the Environmental Protection Agency’s maximum contaminant level (10 parts per billion), one study found that all GIS maps had incomplete arsenic water sampling data in tribal areas belonging to the Navajo and Hopi tribes. This means a comprehensive picture of drinking water arsenic levels could not be made in tribal lands in Arizona. With deficient information, this problem has the potential to become exponentially worse over time.

I gave you all the information and bad news up front, so I could finish with something a bit more positive. Regulatory efforts have been made to ensure lower arsenic levels are present in occupational settings.

The Occupational Safety and Health Administration, sets an eight-hour permissible exposure limit of 10 micrograms per cubic meter for inhalational arsenic, with an action level of five micrograms per cubic meter. This was based on research done by the National Institute of Occupational Safety and Health, which has a recommended exposure limit of two micrograms per cubic meter during any 15 minute period. In conjunction with this, the American Council for Government Industrial Hygienists proposed a similar threshold limit value of 0.1 micrograms per cubic meter for an eight-hour work day.

General human health is highly vulnerable to arsenic exposure, but Indigenous tribes in particular have demonstrated deleterious effects from arsenic exposure. What complicates the matter is due to either errors of commission or omission, incomplete data about arsenic levels exists on tribal lands. The future will require greater efforts for a healthy and just world, but the story of arsenic can become historical rather than contemporary.

Dominik Dabrowski is an occupational and environmental medicine physician at HealthPartners and a graduate student at the University of Minnesota’s School of Public Health.