Guidance

Sulphuric acid: general information

Updated 11 November 2024

Overview

Sulphuric acid is a clear, colourless, or brown oily liquid that is highly corrosive. It is a very important chemical worldwide.

Uses of sulphuric acid

The largest use of sulphuric acid is in the production of phosphate fertilisers. It has other uses, in the petrochemical processes, to control the acidity of foods, oil refining, metal extraction and processing, to make hydrochloric and hydrofluoric acids and to produce other industrial chemicals. It is also used to harvest potatoes; the acid damages the leaves killing the plant and making it easier to lift the potatoes from the ground.

Sulphuric acid may also be used to make plasticisers, dyestuffs, rubber, explosives, silicate for toothpaste, adhesives, detergents, pharmaceuticals, edible oils, lubricants, and food acids such as citric or lactic acid.

Sulphuric acid is also used in lead-acid car batteries and some commercially available solutions for unblocking drains.

How sulphuric acid gets into the environment

Industrial processes and agriculture may release sulphuric acid into the environment. Burning fossil fuels releases sulphur dioxide which can react with oxygen and water in air to form sulphuric acid. This contributes to ‘acid-rain’ which can cause environmental damage.

Sulphuric acid is not persistent in the environment, being quickly neutralised on release.

Exposure to sulphuric acid

At home, people may be exposed to sulphuric acid as it is present in some household cleaning products and car batteries.

Exposure to sulphuric acid may also occur if it is used where you work; however safe levels are enforced to protect employees who may be exposed to sulphuric acid at work. Such levels are below those that are thought to cause harmful effects.

How exposure to sulphuric acid can affect your health

The presence of sulphuric acid in the environment does not always lead to exposure. In order for it to cause any adverse health effects, you must come into contact with it. You may be exposed by breathing, drinking or by skin contact with the substance. Following exposure to any chemical, the adverse health effects, you may encounter depend on several factors, including the amount to which you are exposed (dose), the way you are exposed, the duration of exposure, the form of the chemical and if you were exposed to any other chemicals.

Strong solutions of sulphuric acid are highly corrosive and can cause skin burns on contact; they may also damage the eyes. Dilute solutions may cause irritation to the eyes and skin. Drinking a solution of sulphuric acid will burn the mouth, throat, and stomach.

Breathing air with high levels of sulphuric acid can cause irritation of the eyes nose and throat, cough, shortness of breath and chest pain; in severe cases there may be lung damage. Breathing air contaminated with sulphuric acid over a long period of time can cause damage to teeth, throat, and lungs.

Sulphuric acid and cancer

Sulphuric acid or its solutions are not classified as cancer causing chemicals. However, studies of workers exposed for a long time (over years) to strong inorganic acid mists which may contain sulphuric acid, have shown an increased risk of cancer of the larynx (voice box) and possibly of the lung.

Environmental concentrations of sulphuric acid are generally much lower than those found in occupational settings and are unlikely to result in cancer.

Vulnerable people

When exposed to the same amount of sulphuric acid, asthmatics have had more breathing difficulties than healthy people. This suggests that asthmatics may be more susceptible to the effects of sulphuric acid.

Pregnancy and the unborn child

There is no evidence to suggest that sulphuric acid, at concentrations that do not affect the mother, can affect the health of the unborn child.

Children

If children breathe, ingest, or touch sulphuric acid they will have similar effects to those seen in adults. Sulphuric acid containing products in the home should be stored in an appropriate container and kept out of the reach of children.

What to do if you are exposed to sulphuric acid

You should remove yourself from the source of exposure.

If you have got sulphuric acid on your skin, remove soiled clothing (not over the head), wash the affected area with lukewarm water and soap for at least 10 to 15 minutes and seek medical advice.

If you have got sulphuric acid in your eyes, remove contact lenses, irrigate the affected eye with lukewarm water for at least 10 to 15 minutes and seek medical advice.

If you have inhaled or ingested sulphuric acid seek medical advice.

Disposal of sulphuric acid-containing car batteries

It is illegal to dispose of vehicle batteries along with normal household waste. As they contain lead and sulphuric acid, they are hazardous to people and the environment. Advice on how to deal with old batteries can be provided by your local authority. The supplier of a new battery may also be able to recycle the old one.

Additional sources of information

NHS Choices - Acid and chemical burns

NHS Choices - Poisoning

UKTIS - Best Use of Medicines in Pregnancy

Email chemcompendium@ukhsa.gov.uk if you have any questions about this guidance or enquiries@ukhsa.gov.uk if you have any other questions.

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