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To: Chairman of the Government Commission
Vice Prime Minister of Kyrgyz Republic, B. Silaev
c.c. Minister of Health
Minister of Environment
Bishkek, June 9, 1998
The first main question: is there danger to life in the Barskoon area, here and now?
- Except for a possible exposure route through the consumption of some vegetables (that are not deeply rooted), there is now, more than two weeks after the accident in Barskoon, no danger to life in the area.
- Meat, milk, all kind of fruits, potato's and wheat can be
consumed safely.
Information on the consumption of plants that are not deeply rooted, such as lettuce, radish, onions will be given by e-mail to WHO-Bishkek later in this week.
The answer of this first main question is based on:
- our measurements of free cyanide in soil on different suspect places, at 6-7 June 1998;
- our measurements of total cyanide in soil and in water on suspect places in samples taken 27-28 May 1998;
- "worst case" calculations of the concentration of cyanide in the surface layer of the soil in the polluted area;
- knowledge of chemical pathways of cyanides in the environment
- knowledge of natural processes in aerated soils by which the cyanides are kept at harmless level
The Lake Issy-Kul and its Future
As Lake Issy-Kul is very large the final concentration of Cyanides from the accident, even in the "worst case" assuming all spilled cyanide in the Lake, will be extremely low.
From measurements in a suspected place, in the bay near the outlet of the Barskoon river, no cyanide (this means <0.001 mg/L) could be detected in a sample taken on 28 May 1998.
In conclusion: There is no longer any danger to forms of life in the Lake.
Air
No gaseous cyanide (HCN) could be detected by our portable cyanide-in-air measurement device, in the Barskoon region, on many suspect places, even not in acidified soil samples.
It is expected that as sodium cyanide is in contact with water, a large fraction of it will be transformed to Cyanide gas (HCN). This process occurs immediately, and its extent depends on the pH of the water.
Cyanide gas level may have been dangerous only the first day after the accident. Any smell of cyanide gas after a week is highly unlikely.
Note: also the applied hypochloric salt that has been sprayed in the canals after the accident, has a "chemical odour".
Recommendations
- Accept a concentration in soil of free cyanide lower than 1 mg/kg as a safe value for human, animal and plant life.
- Accept a concentration in (drinking and surface) water of free cyanide lower than 0.1 mg/L as a safe value for human, animal and plant life.
- Accept that complexed cyanide in soil although undesired, is not harmful upon exposure to human, animal and plant life.
- Accept that the uncertainty in the measurements of low concentration cyanide (< 1 mg/kg or 0.1 mg/L) if high, easily rising to over 100%. Therefore it is advised to round all data for cyanide concentrations (free or complexed) to only one digit after the decimal point, in mg/kg (soil, solic samples) and mg/L (water).
- Accept that low concentrations of cyanides (all forms of cyanide, below 1 mg/kg in soil and below 0.1 mg/L in water) can be part of natural processes.
- Consider as polluted area only the soil that has been in
contact with irrigation water.
At present, more than two weeks after the incident, the river water, the canal water, the water in the Lake and the air should no more be mentioned as "polluted".
There will be remains of soil pollution by cyanide at low, harmless levels for a long time.
- Since the measured concentration of cyanide in soil suspected places in Barskoon are now (June 6, 1998) below 1 mg/kg, flushing is no longer a requirement.
- Since the measured concentration of cyanide in soil on suspected places in Barskoon are now (June 6, 1998) below 1 mg/kg, the restriction for children to be in contact with the soil, can be relieved.
- Washing hands after contact with soil is to be advised for any soil.
- In Gagarin Street N 53 in Barskoon, we measured a total cyanide concentration of 0.7 mg/kg (wet soil) after 7 days.
This means:
- a strong indication of pollution in the days before, since the cyanide level will decrease daily
- a level lower than 1 mg/kg, and thus - now - without any threat for life. Although it will take a long time to reach background levels again, it is expected that in aerated soil the remaining (harmless) level of cyanides will decrease continuously.
Bishkek, June 9, 1998
Dr. Mark Bruggen
Mr. Robert Cleven
WHO experts