WHO Knows About Thallium

Notes about Thallium from Environmental Health Criteria document 182 by World Health Organisation

By Allan Gow, 27/1/1999

Allan Gow was an active contributor to the North Lake Macquarie Environmental Health Liaison Meetings held near Newcastle in NSW, until the meetings were cancelled by the Health Department in early 1999. Allan was a neighbour of the Pasminco Lead Smelter at Boolaroo who discovered that 0.6 tonnes of Thallium was stored on the site of the smelter. He summarised the World Health Organisation (WHO) Criteria Document on Thallium, for the benefit of other residents. We reproduce his notes here also because thallium has been found in ceiling dust in Sydney homes that have been tested. Only the results from one of the 40 homes tested has been published (see LEAD Action News vol 7 no 2, 1999). The results were Thallium in the Flue Dust (dust sitting inside the flue pipe that vented from a coal gas burner into the ceiling cavity) Sample: 3 mg/kg (milligrams per kilogram) and Thallium in the Ceiling Dust Sample: <0.5 mg/kg. "Normal" soil range: 0.1 - 0.8 mg/kg.

Notes about THALLIUM:

• Rapidly absorbed via Stomach, Lungs & Skin & affects all internal organs progressively.

• Thallium 1 carbonate induces chromosomal aberrations plus Gene mutation.

• 0.5 gram is a fatal dose in 1 to 2 days.

• At 10-15 mg/Kg of Body Weight (Daily) = Dead in 10-12 days.

• Leaves the body through Urine (non-cumulative) (30 days?) if you're not dead.

• Above background levels it is recommended that Bio monitoring of population living in the vicinity of the source be carried out.

• World production 10?15 tonnes. Pasminco = 0.6 tonne at Boolaroo suggests Blood, Urine, Hair Testing and Saliva is necessary.

• U.S.A. stopped production in 1981.

• Average daily intake for adults is estimated to be 0.005 mg/Day (= 5 µg/Day)

• 1 µg/Day can be tolerated by Vast Majority of Humans. Exposure to small amounts ? eat more potassium foods.

• Speeds up ingestion of selenium in kidneys and liver where thallium is released significantly.

• 1.0 µg/Litre in water can deliver effects. Detection limit in 1987 was 5µg/Litre. Better analysis techniques are used now.

• 0.01 µg/Litre can be found in some "unpolluted" fresh water.

• 5mg/kg has been found in sediments.

• Pale Blue in Colour. Fumes are Odourless * Colourless * Tasteless.

• In research laboratories, for amounts greater than 0.01 mg (= 10 µg) - storage containers are to be sealed and clearly marked.

• Access to rooms where used should be restricted.

• Has high specific gravity (Heavy metal). Has 2 isotopes:- 203 and 205.

• Increased levels were found around H2S04 (sulphuric acid) plant.

• Flue dust is a source of thallium as it is released in concentrations of the smallest particles that pass through filters.

• Even wool is not a satisfactory filter material.

• Vapours and dust similar texture to Lead and melts at 303°C, that is 1/2 the melting point of aluminium (Al).

• Melted thallium accumulates in top levels of soil, decreases at depth.

• The weather side of a hill opposite a smokestack is a Collector.
  Accumulates in the chlorophyll as it is taken up by Plants. Uptake by plants increases as soil pH decreases.

• Thallium in soil and vegetables from "acid rain" areas should be determined.

• Does leak from soil into local water. Easily soluble in Acid soil. Trees can be a long-term reservoir of thallium.

• Plant uptake increases with increased use of sewage sludge and Potash Fertilizers.

• Waste material from mining mercuric oxide and coal containing 25-106 mg/kg resulted in chronic poisoning in China (1981?).

• Prussian blue used as treatment is suspect.

N.B. Cadmium: One of the most toxic of heavy metals in the "Freshwater environment."

Editor's note: perhaps cadmium will be Allan's next project. It is also found in ceiling dust. Thallium is no longer used in developed countries due to concerns about its toxicity - however it is still used in developing countries as a rodenticide (rat poison) due to its cheapness.