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Is copper sulphate harmful to my family?

We live about 50 yards from a vineyard. Last night while we were sleeping they sprayed copper sulphate. Is this harmful to my family? In the future should we leave when the spraying is going on? Thank you.

June Mcphee
- Templeton, California
2002

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As far as I know, there is no exposure limit, either in Europe or under OSHA in the USA, for copper salts, so they can, in theory, be considered safe. However, saying that, the exposure limit for copper as copper is 0.2 mg/m3 for copper dust and fumes and 1 mg/m3 for copper as copper. I consider this to be contradictory as exposure to any heavy metals is not good. Copper salts, especially copper carbonate ⇦this on eBay or Amazon [affil links] (in the old days) was used to treat rust and fungal growth on vines, so some of it must have got into the wines produced from these grapes. This mixture was called Bordeaux Mix and is well known. I believe in the USA there is a legal requirement for users of copper sulphate ⇦this on eBay or Amazon [affil links] to tell the public of its application.

Any chemical can enter the body through numerous paths, inhalation, ingestion and through the skin. I would expect any exposure you may have suffered would be through inhalation, so it may irritate your lungs if it is sufficiently high. It could also have entered through the mouth and hence be ingested. For metals to be harmful they must be "bio available"; that is, they must be in a form where they can affect the body's chemistry; this is usually as a soluble salt that dissolves in the body's fluids. copper sulphate is quite soluble, so this route is possible.

Exposure to high concentrations of copper salts can cause nausea, vomiting, gastric pain and diarrhea. If it gets in the eyes it can case severe irritation and corneal clouding. copper sulphate has an LD50 of 300 mg/kg for rats, so it is not particularly toxic. As far as I am aware, there are no long term effects associated with copper, but this is really a relatively new science and we are learning all the time. Obviously if you are suffering from any of these symptoms, you should contact your doctor immediately.

You may also like to discuss this problem with your environmental health officer, just to put your mind at rest.

Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK
2002

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copper sulphate(or sulphate, for you non-spellers) has been used for a long time in surface water to control algae growth. This includes drinking water supplies as well. Common dosage was in the 2 mg/l (as copper sulphate) range. It was generally considered safe at this level.

George Brackett III
- Utica, New York
2002

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I am looking for small quantities of copper sulphate . My grandmother always used "Blue stone" as a canker sore remedy. It is added to animal feed, water supplies, etc.. but I can find no information on copper sulphate as used for medicinal purposes. Can any one help?

Rebecca Buzzell
- Strafford, New Hampshire
2003

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Ed. note:letter 22762 is about copper sulphate being used for medicinal purposes in the old days.