What Are the 8 RCRA Metals?

Overview

According to the Environmental Protection Agency or EPA, the Resource Conservation and Recovery Act or RCRA is a federal law that provides a structure for the proper management of hazardous and non-hazardous solid wastes. Its purpose is to give the EPA the authority to handle these waste products - from generation to transportation to treatment to storage to, finally, disposal. These hazardous and non-hazardous waste products that the EPA controls under the RCRA can also include certain metals. Also called the RCRA 8s, these metals are Arsenic (As), Barium (Ba), Cadmium (Cd), Chromium (Cr), Lead (Pb), Mercury (Hg), Selenium (Sg), and Silver (Ag). Follow along as we discuss each RCRA metal and its proper disposal.

1. Arsenic (Waste code: D004)

Arsenic, is a type of material that is most known to be used as a poison, especially in the olden days. However, Arsenic is commonly found in our food, water, and dietary supplements, in small amounts, though. It is also known to be present in tobacco smoke, which research shows to have high concentrations of Arsenic. Yes, in small amounts Arsenic poses no harmful effects for the human body. If one consumes a certain amount of Arsenic, it can become quite toxic.

2. Barium (D005)

Barium is one of the more common elements, and is also one of the most reactive. It can be used in the coloring of fireworks, the production of fluorescent light bulbs and tiles. You can also find Barium in rat poison and in drill bits, which one can find in oil refineries. Humans can be unknowingly exposed to Barium through well water supplies and oil refineries as well.

3. Cadmium (D006)

According to a study, Cadmium is a natural metal, which you can find in the earth’s crust. It can be extracted when one produces metals, including Copper, Lead, and Zinc. Cadmium is a blue-grey soft metal, and it also has multiple uses. The soft metal can be used in the production of batteries, plastics, metal coatings, and pigments. Plus, you can also find this toxic metal among mushrooms, shellfish, mussels, cocoa powder, and dried seaweed. A human can also unknowingly ingest this through secondhand smoke.

4. Chromium (D007)

Chromium is a brittle metal element which one can find in chrome plated car parts. It is naturally found in the Chromite Ore, but it can also be found in soil, rocks, plants, and even some animals. This metal has only been used for the longest time; in fact, China’s Qin Dynasty used this metal to coat the weapons of the world famous Terracotta Army. As with other metals, it can become poisonous to humans when exposed to high amounts of Chromium.

5. Lead (D008)

Lead is a well-known metal that one can find ammunition, batteries, old paints, crafted metals (pipes and solder), and X-ray protection equipment. Its potential health risk is also a well-documented fact. It is produced through the burning of fossil fuels, mining, and manufacturing. When these processes are being done, lead is exposed to the air and can find its way into water systems. This can lead to what is known as “lead poisoning,” which is known to have disastrous effects on the brain as well as causing cancer.

6. Mercury (D009)

Mercury is a liquid metal which you can find in most glass thermostats, batteries, and dental fillings. It is produced through the burning of coal. It can also be generated by manufacturing plants and mining. Mercury, when people and the environment are exposed to large amounts, can already provide a health risk. However, it can also be hazardous to human health when it is mixed with other elements. A good example of this is mercury poisoning through ingesting methyl-mercury which can be found in a few fish species. When exposed to dangerous amounts of the liquid metal, it can cause tremors, impaired cognition, and disturbances in the circadian rhythm.

7. Selenium (D010)

Selenium is a type of metal that is typically found in soil. But, it can also be produced when there is the refinement of metal sulfide and metal ores. Although it can be poisonous to people when ingested in large amounts, Selenium provides health benefits in small doses. These include improvement in thyroid function and metabolism. Plus, it can also reduce the risk of heart disease, slow mental age decline, and help boost your immune system. Selenium is used mostly in electronics, but it can also be used in glass, pigments, inks, rubber, enamels, and paints. In addition, one can also find Selenium in pharmaceuticals, anti-dandruff shampoos, poultry and livestock feed, pesticides, and fungicides. Too much ingestion of Selenium, though, can lead to what is known as selenosis or selenium poisoning.

8. Silver (D011)

Silver is one of the most common types of metal. You can find it in jewelry, dental fillings, silverware, and mirrors. Plus, its use can range from multiple industries. For instance, Silver can be used in the production of photos and in the brazement of alloys and solders. It can also be used in electronics, water (drinking and in swimming pools) disinfectants, lozenges, chewing gums, and as an antibacterial agent. It is produced from the extraction of copper, lead, zinc, and gold ores. When there is inhalation or ingestion of Silver, it can lead to argyria. It is a disease that can cause the color of the skin to blue or grey color. It can also lead to other negative health effects, such as throat and lung irritation, stomach pain, and breathing problems.

EPA Limits for RCRA Metals

As stated earlier, all these metal elements can potentially be hazardous to people. However, this only applies when a person is exposed, whether through inhalation or ingestion, to large amounts of the metals mentioned above. That is why the EPA provides a limit to the volume of RCRA metals that can be present in a consumer’s household and that can also be disposed of in solid waste landfills. See below the limits that the EPA set for each RCRA metal. Note: These are measured in parts per million (mg/L).

Metal	EPA Allowable Limits
Arsenic	5.0 ppm (mg/L)
Barium	100.0 ppm (mg/L)
Cadmium	1.0 ppm (mg/L)
Chromium	5.0 ppm (mg/L)
Lead	5.0 ppm (mg/L)
Mercury	0.2 ppm (mg/L)
Selenium	1.0 ppm (mg/L)
Silver	5.0 ppm (mg/L)

When an amount of RCRA metal waste exceeds the limit set by the EPA, it must be treated as a hazardous waste. However, as aforementioned, when the amount is less than the limit itself, it can be disposed of in ordinary landfills. This, in fact, is the more cost-effective disposal solution. Although, for you to dispose of an RCRA metal at a standard landfill, it must first pass the Toxicity Characteristic Leaching Procedure (TCLP) test. This test would stimulate the leaching process, which would happen normally in a standard landfill. Then, it would allow the proper employees to test the sample gathered from the leaching. Find out more about this process when you continue reading below.

Toxicity Characteristic Leaching Procedure (TCLP)

The Toxicity Characteristic Leaching Procedure (TCLP) is a type of test that can provide an answer whether or not a waste product contains large amounts of hazardous compounds. It is a method that is used to stimulate the leaching process of a waste landfill. This can analyze the volume of the hazardous elements that are within the waste products. It also includes four processes, which are the following:

• The sample and preparation for the leaching process.
• The gathering of the leachate sample.
• The preparation of the leachate sample for analysis.
• The leachate analysis result.

With the TCLP test, you can better understand whether an RCRA metal or any other potentially hazardous waste product can be land-disposed or not. Additionally, there are also a few equipment that facilities use for the TCLP test.

Agitation Apparatus

For an agitation apparatus to be deemed viable, it must be capable of rotating the extraction vessel in an end-to-end fashion at 30 ± 2 rpm. There are also various devices that the EPA finds suitable for TCPL. These are the following (including a few companies that offer them and also their model numbers):

Analytical Testing and Consulting Services, Inc.

Warrington, PA (215) 343-4490

• 4-vessel extractor (DC20S)
• 8-vessel extractor (DC20)
• 12-vessel extractor (DC20B)
• 24-vessel extractor (DC24C)

Associated Design and Manufacturing Company

Alexandria, VA (703) 549-5999

• 2-vessel (3740-2-BRE)
• 4-vessel (3740-4-BRE)
• 6-vessel (3740-6-BRE)
• 8-vessel (3740-8-BRE)
• 12-vessel (3740-12-BRE)
• 24-vessel (3740-24-BRE)

Environmental Machine and Design, Inc.

Lynchburg, VA (804) 845-6424

• 8-vessel (08-00-00)
• 4-vessel (04-00-00)

IRA Machine Shop and Laboratory

Santurce, PR (809) 752-4004

• 8-vessel (011001)

Lards Lande Manufacturing

Whitmore Lake, MI (313) 449-4116

• 10-vessel (10VRE)
• 5-vessel (5VRE)
• 6-vessel (6VRE)

Millipore Corp.

Bedford, MA (800) 225-3384

• 4-ZHE
• 4 2-liter bottle extractor (YT31ORAHW)

Extraction Vessels

There are two types of extraction vessels; one is the Zero-Headspace Extraction Vessel or ZHE, and the other is the Bottle Extraction Vessel. The difference is that ZHE is used when the waste is being tested for the mobility of analytes. A Bottle Extraction Vessel, on the other hand, is used when the waste that is being evaluated only requires a nonvolatile extraction.

Filtration Devices

The EPA highly recommends that all filtration processes should be performed in a hood. Aside from that, a ZHE can also be used for extraction when the waste being extracted is evaluated for volatiles. It also must be able to withstand the pressure of 50 psi. There is also a filter holder device that is used when the waste is evaluated for other reasons aside from volatile analytes.

Filters

When it comes to filters, the EPA sets strict specifications regarding the correct filters to use. According to the Agency, filters must be made with borosilicate glass fiber, they must not be made with any binder material, and their effective pore size must be 0.6 µm to 0.8 µm. Learn more about filter specifications accepted by the EPA here.

pH Meters

According to the EPA, pH meters must be accurate to the ± 0.05 unit, and the temperature should be at 25°C.

ZHE Extract Collection Devices

For ZHE extraction, the EPA recommends the use of TEDLAR bags or glass and  PTFE gas-tight stainless steel syringes can all be used to collect the liquid phase of the waste as well as the final extract when using a ZHE extracting device. Although, the Agency specifically states that one can use this device when they are met with the following conditions:

• If the waste product contains less than 1% of non-watery liquid phase, one can use a TEDLAR bag or a 600 mL syringe can be used to extract as well as combine the initial liquid and solid extraction.
• If the waste does not contain any liquid phase or is 100% solid waste, or if the waste is 100% liquid, one can use either a TEDLAR bag or a syringe. In the event that the syringe is used, one should discard the initial 5 mL of watery liquid phase from the syringe. This means that the remaining liquid phase extract will be used for analysis.
• If the waste product contains more than 1% of the total waste, both the TEDLAR bag and syringe can be used for the separation of the solid and liquid waste as well as the final extract filtration. However, analysts should only use one, not both.

ZHE Extraction Fluid Transfer Devices

This is any device that can transfer the extraction fluid into a ZHE device without changing the nature of the extraction fluid. These devices are accepted by the EPA:  a gas tight syringe,  pressure filtration unit, or a peristaltic pump.

Laboratory Balance

The EPA recommends any laboratory balance that is accurate to the ± 0.01 gram can be used.

Beaker or Erlenmeyer Flask

It needs to be made of glass and should be 500 mL.

Watchglass

It needs to have the correct diameter which can cover the beaker or the erlenmeyer flask entirely.

Conclusion

If you are a hazardous waste generator, it’s vital to understand the intricacies that makes up hazardous waste. It can spell the difference between proper compliance or hefty fines. Does your organization produce waste with traces of the RCRA’s 8 Metals? If you require help in removal, disposal or transportation, it’s best to contact ACT. We’ll be happy to help.