Sources of Exposure

• The US Food and Drug Administration (FDA) flagged certain incidents in 2019 showing excess radiation exposure due to incorrect use of rubidium 82 in Positron Emission Tomography (PET) scans.
•  Rubidium Rb 82 injection is used to diagnose heart disease in adults.
• The element is used as a mild radioactive dye to produce an image of the heart in PET scans.
• The FDA identified 2 PET scanner systems with user errors, namely CardioGen-82 and Ruby-Fill.
• These two systems require additive-free 0.9% sodium chloride injection USP to elute the generator.
• Investigation showed that incorrect solutions were used in several instances that allowed strontium radioisotopes to break through the rubidium injection given to patients.
• The FDA therefore required Safety Labeling Changes on labels of rubidium 82 generators to remind system users how to prepare the correct solution for the generator.
• The British Medical Bulletin also reported that rubidium-82 positron is being used in myocardial perfusion scintigraphy (MPS) PET to diagnose and manage coronary artery disease.
•  Frontiers in Medicine reported in 2015 that "During the last 10 years, with the increased number of PET/CT systems and the higher strontium-82 production capabilities, the number of patients injected with rubidium-82 in the USA dramatically grew even if it still represents a small percentage by comparison with the use of 99mTc-sestamibi and 99mTc-tetrofosmin."
• The paper also adds that rubidium-82 is available daily in nuclear cardiology departments, with a generator capable of being used for 28 to 42 days.

•  Rubidium oxide is used in the manufacture of glass, optics, and ceramics.
• American Elements reports that rubidium oxide is usually insoluble in water.
• It is also extremely stable which makes it ideal for use in ceramic structures such as clay bowls.

• Rubidium oxide is also found in extremely thin batteries.
• At 20°C, rubidium's conductivity is the same as sulfuric acid.
• It is also used in solid oxide fuel cells for its ionic conductivity.

•  Thermofisher explains that rubidium as a metal salt produces a purple color in fireworks.
•  Rubidium nitrate is a white powder highly soluble in water and slightly soluble in acetone.
• Pyrotechnic stars used in fireworks contain this color-producing chemical along with fuel, oxidizer, chlorine for enhancing color, and a binder.

• According to LennTech, plant will adsorb rubidium in case potassium is deficient.
• One example is sugar beet which, when stressed by potassium deficiency, responds by adding rubidium.
• This way rubidium joins the food chain and contributes to a daily intake of 1 mg up to 5 mg.

Health Effects

• The US Environmental Protection Agency (EPA) published the paper "Provisional Peer-Reviewed Toxicity Values for Rubidium Compounds" in 2016 listing acute and subchronic effects of exposure to the element.
•  Short-term effects in humans at 2.6-10.3 dosimetry (oral doses expressed as ADD or mg/kg-day) include weight gain, diarrhea, nausea or vomiting, excitement or agitation, and polyuria.
• At 5.1 and 10.3 dosimetry, short-term effects include skin rashes and diarrhea.
• At 14.3 or 21.4 dosimetry, short-term effects include change in EEG and temporary slowing of pulse.
•  Sub-chronic effects in rat subjects at 0 to 2,000 dosimetry include death (dependent on dose and time), congested liver, bronchitis or bronchopneumonia and kidney congestion.
• At 167 to 500 dosimetry, subchronic side effects to rats include convulsive seizures in response to sound and light.
• At 0 to 564 dosimetry, subchronic effects to rats include death, convulsions, and reduced weight gain.
• The full table of side effects for rubidium chloride at varying levels can be reviewed here (pp. 7-12, 24).
•  Drugs.com lists the following side effects of rubidium (incidence not known): "Bleeding, blistering, burning, coldness, discoloration of skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site."
•  LennTech lists the following effects of overexposure to rubidium: inability to gain weight, ataxia, nervousness, skin ulcers, and hyper irritation.
•  Heart conditions and potassium imbalance may also be aggravated by exposure to rubidium.