What Is Thallium?

ATSDR says thallium pesticides were used in the past to control rodents and insects, that this use was banned in 1972, and that US production of thallium ended years ago. EPA drinking water regulations at 40 CFR 141.62 set a maximum contaminant level for thallium of 0.002 mg/L for community and non-transient, non-community water systems.

ATSDR says hair loss, numbness and pain in the feet and hands, gastrointestinal effects such as diarrhea, abdominal pain, nausea and vomiting, and heart problems have been observed in people poisoned with thallium. A 2023 case report in the Journal of Clinical Neurology describes scalp hair loss appearing on day 9 in a patient with gastrointestinal symptoms and peripheral neuropathy, after which blood and urine tests confirmed thallium poisoning. A 2021 case report in Brain and Behavior describes a 43-year-old man who was misdiagnosed with gastroenteritis, diabetic nerve damage and Guillain-Barré syndrome over 21 months before blood and urine tests confirmed thallium poisoning, and says that after Prussian blue treatment his gastrointestinal symptoms, skin lesions and hair loss recovered, although nerve damage remained.

In 2003, the FDA approved a new drug application for Radiogardase, also known as Prussian blue, to treat people with harmful levels of cesium-137 or thallium, and said it works by increasing the rate at which these substances are eliminated from the body. The FDA said the application followed its January 2003 announcement that Prussian blue, when produced under conditions specified in approved marketing applications, is safe and effective for treating exposure to radioactive thallium, non-radioactive thallium or radioactive cesium.