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Hazardous Waste Management Of RCRA 8 Metals

February 7, 2024

This entry describes the eight metals of particular interest to the EPA for being highly toxic, and how each therefore requires “cradle-to-grave” hazardous waste management. Q&As include:

  1. What are the RCRA 8 metals?
  2. Why are they called RCRA metals?
  3. How & why is arsenic a RCRA hazardous substance?
  4. How & why is barium a RCRA hazardous substance?
  5. How & why is cadmium a RCRA hazardous substance?
  6. How & why is chromium a RCRA hazardous substance?
  7. How & why is lead a RCRA hazardous substance?
  8. How & why is mercury a RCRA hazardous substance?
  9. How & why is selenium a RCRA hazardous substance?
  10. How & why is silver a RCRA hazardous substance?
  11. What are the EPA limits for RCRA metals in landfills?
  12. How do you properly dispose of waste contaminated with RCRA 8 metals?


What are the RCRA 8 metals?


In alphabetical order: arsenic, barium, cadmium, chromium, lead, mercury, selenium, and silver. Each is extremely toxic, meaning that it can be harmful or fatal if ingested or absorbed, or that it can leach into the soil or groundwater when landfilled.

Also, these are heavy metals, which are implicated in gastrointestinal and kidney dysfunction, nervous system disorders, skin lesions, vascular damage, immune system dysfunction, birth defects, and cancer.

If any part of your operations involves one of these metals, in EPA parlance, you must manage it as a hazardous waste from “cradle-to-grave.” I.e., from its initial generation throughout its transportation, treatment, storage, and ultimate disposal.

[Per some sources, there are only five heavy metals: mercury, lead, chromium, cadmium, and arsenic. Barium and silver are apparently relative lightweights. And selenium, similar to arsenic, is not really a metal at all (see source). It’s actually used sometimes to detoxify heavy metals (see source)].


Why are they called RCRA metals?


Although commonly bandied interchangeably, the initialisms “EPA” and “RCRA” refer to two different things. To wit:

  • RCRA (aka, Resource Conservation and Recovery Act) is the body of Congressional eco-law that gives us the EPA (aka, Environmental Protection Agency).
  • The EPA is the implementing arm of the RCRA, ostensibly limited to enforcing the eco‑laws enacted by Congress, but lately prone to making up its own rules on the fly.

Thus, in matters of concern to the EPA, “RCRA” often appears as an adjective. In this case, the “RCRA 8.” (BTW. The hazmat cognoscenti transmogrify “RCRA” into an acronym. They say “rick-rah,” as in “Rick-rah 8.”)


How & why is arsenic a RCRA hazardous substance?


Arsenic is a ubiquitous carcinogen indispensable in the manufacture of electrical circuits, wood preservatives, and pesticides. Curiously, it’s not harmful to humans if ingested or absorbed in lesser amounts. So, it commonly shows up in food, water, and other things (e.g., dietary supplements). But in large enough quantities, this stuff can be fatal. According to our Russian sources (just kidding), you need 70 to 180 milligrams (mg) or about 600 micrograms per kilograms (kg)/day to kill a political rival or heretic.


How & why is barium a RCRA hazardous substance?


Barium is a soft, silvery metal that rapidly tarnishes in air and reacts with water. Not extensively used—you’ll find most of it in drilling fluids (for oil or gas wells). It’s also used in paint, glassmaking, and for providing color to fireworks (see source).

Although barium is relatively insoluble in water, it’s toxic to humans because its constituents are soluble in the gastrointestinal tract, the main ones being chloride, nitrate, and hydroxide.

Thereby, the CDC helpfully reports that “eating or drinking very large amounts of barium compounds that dissolve in water or in the stomach can cause changes in heart rhythm or paralysis in humans,” and that “some people who did not seek medical treatment soon after eating or drinking a very large amount of barium have died.”

Disappointingly from a Darwinian perspective, the CDC does not reveal why anyone would choose to eat or drink a large amount of barium, especially since it’s also used in rat poison.


How & why is cadmium a RCRA hazardous substance?


Cadmium is a soft, malleable, bluish white metal found in zinc. Most of what’s produced nowadays is obtained from zinc byproducts or recovered from old nickel-cadmium batteries. It was first used in the early 1800s as a yellow, orange, and/or red pigment. But now it’s an important constituent of nickel-cadmium (Ni-Cd) batteries. And it’s also handy as a sacrificial corrosion-protection coating for iron and steel.

Unfortunately, cadmium and its compounds are highly toxic. Exposure to them is known to cause cancer, targeting the body’s cardiovascular, renal, gastrointestinal, neurological, reproductive, and respiratory systems.

Per OSHA, manufacturing and construction workers are particularly susceptible to cadmium exposure. (E.g., the production of batteries, plastics, coatings, and solar panels; metal smelting & refining; landfill and recycling operations; and a potpourri of other human endeavors (see source).


How & why is chromium a RCRA hazardous substance?


Good question. Especially since chromium is an essential mineral for the human body, albeit in trace amounts. It augments the action of your hormone insulin. Naturally present in a wide variety of foods, it also helps break down and absorb carbohydrates, proteins, and fats. (So who knew?) Thus, chromium deficiency can increase the risk of diabetes (see source).

Acute chromium poisoning most likely comes via the oral route. E.g., somebody downs one‑to‑three grams of the stuff to do himself in.

Chronic chromium poisoning comes mainly from prolonged accidental inhalation or skin contact. This is rare, and so chromium poisoning is unusual in occupational environments. Long-term studies in which animals have been exposed to low levels of chromium in food or water have produced no harmful effects (see source).


How & why is lead a RCRA hazardous substance?


Lead is a neurotoxin that accumulates in soft tissues and bones, damaging the nervous system and interfering with the function of biological enzymes. This can cause neurological disorders (e.g., behavioral problems and brain damage). Lead also impacts the cardiovascular and renal systems (see source).

Up until 1978, lead was used as an additive to paints and primers to speed drying, increase durability, maintain a fresh appearance, and resist corrosive moisture. You might think that anything so useful would be an environmental pariah, and you would be correct—in spades.

Odorless, tasteless, invisible, and highly toxic, lead dust disperses into indoor air undetected. Thus, you can be breathing and absorbing it through your skin. And the health dangers are serious and lifelong.

As well as in homes & apartments, lead poisoning is a problem in offices, factories, and other commercial spaces, which is why OSHA has extensive rules regarding how much lead dust an employee can be exposed to during a workday (see source).  BTW, lead paint is still used for road markings, military equipment, and other heavy-duty applications. So be on the lookout. It’s still around.


How & why is mercury a RCRA hazardous substance?


Metallic mercury is a naturally occurring shiny, silver-white metal, historically referred to as quicksilver. It’s liquid at room temperature. You can find it in older thermometers, fluorescent light bulbs, and some electrical switches. When dropped, elemental mercury breaks into smaller droplets that can go through small cracks or become strongly attached to certain materials.

Metallic mercury is only moderately toxic in liquid form. But it becomes extremely noxious in its gaseous state, as it’s easily respired by the human body, entering the bloodstream to contaminate any number of vital organs that you’ve come to depend on over the years. Symptoms of overexposure include tremors, impaired cognition, and disturbances in the circadian rhythm.

Such toxicity has engendered ever-increasing levels of mercury hazard regulation at federal, state, and local levels. Among them are stricter product-labeling requirements; sale prohibitions on certain products containing mercury; and in many jurisdictions, outright bans on mercury disposal, along with mandates for mercury recycling.


How & why is selenium a RCRA hazardous substance?


Selenium is another one of those Jekyll & Hyde things (see Q.6). As stated previously, it really isn’t a metal. It’s a mineral that’s found in soil. It appears naturally in water and some foods. And the human body needs a tad of it onboard to aid & abet metabolism. Yet…

Chronically high intakes of selenium are dangerous. The smorgasbord of physical consequences includes muscle tremors, hair loss, stomach upset, and lightheadedness. More severe cases can feature heart attacks, respiratory distress, and/or kidney failure (see source).

Factoid: Binging on Brazil nuts can be toxic. They’re exceptionally high in selenium, a single nut containing in excess of the government’s RDA (ibid).

Outside the human body, selenium is used to make pigments. It has both a photovoltaic action (converts light to electricity) and a photoconductive action (electrical resistance decreases with increased illumination). It therefore shows up in photocells, solar cells, and photocopiers (see source).


How & why is silver a RCRA hazardous substance?


A basic element found in soil and water, everyone’s familiar with silver for jewelry. But it’s also important for industry, used to create solder and brazing alloys, batteries, dental amalgams, glass coatings, LED chips, solar panels, and lots of other stuff, including nuclear reactors (see source).

You’re likely exposed daily to very low levels of silver that exist in food, water, and (less so) in the air. On a larger scale, silver might enter the body of a person who, for example, lives near a hazardous waste site and drinks silver-contaminated water, or who eats food grown in soil that’s similarly polluted with it.

In industry & manufacturing, when working with silver, it can enter people’s bodies through the skin. E.g., when they put their hands into solutions containing silver compounds, or when they come into contact with silver-containing powders. Also, they might respire silver dust particles that consequently enter the mouth, throat, and/or digestive tract.

Exposure to relatively high levels of silver dust can cause breathing problems, lung and throat irritation, and stomach pain. Skin contact with silver compounds can cause mild allergic reactions (e.g., rashes, swelling, and inflammation).

Silver compounds can cause the skin (and other body tissues) to turn gray or blue-gray, a condition called argyria that’s lifelong and, while not medically harmful, it can definitely have a depressing effect on one’s marriageability (see source).

What are the EPA limits for RCRA metals in landfills?


Allowable limits of RCRA 8 metals in wastes intended for regular landfills are listed below in milligrams per liter. Wastes that meet or exceed these levels must be treated as RCRA hazardous.

Arsenic – 5.0 mg/L
Barium – 100.0 mg/L
Cadmium – 1.0 mg/L
Chromium – 5.0 mg/L
Lead – 5.0 mg/L
Mercury – 0.2 mg/L
Selenium – 1.0 mg/L
Silver – 5.0 mg/L

How do you properly dispose of waste contaminated with RCRA 8 metals?

Per the RCRA, you’re legally responsible for any toxic waste you generate from “cradle-to-grave.” In other words, once you’ve generated a toxic waste, there’s no way to rid yourself of complete responsibility for it.

It can be a full-time job in itself to ensure that a hazardous waste management vendor is properly licensed and adequately experienced to handle the kind and size of waste stream you generate.

This is especially true in that you’ll need more than one kind of vendor in order to comprehensively manage your hazardous waste stream: transporters, storage sites, treatment facilities, etc.

As in all things involving the EPA, don’t take chances. Get expert advice!

Contact Hazardous Waste Experts now.


Or call 888-681-8923.


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