Naphthalene: general information
Updated 12 December 2024
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Overview
Naphthalene is a white, crystalline solid that is flammable and smells strongly of mothballs.
Uses of naphthalene
Naphthalene is the most abundant component of coal tar, which is the liquid byproduct of the distillation of coal into coke for use as a smokeless fuel.
The most common current use for naphthalene is as a raw material in the production of phthalic anhydride, which is often used in the production of dyes, plasticisers, insecticides and some pharmaceutical products.
In the past, naphthalene was used as a fumigant for repelling moths, for which it is popularly known as mothballs. Another classical use of naphthalene was as a fumigant for soil. Such uses are now discontinued.
How naphthalene gets into the environment
Naphthalene does not occur naturally in the environment. It is most likely to enter the environment from workplaces where it is manufactured or used. It may also be released into the environment due to burning organic material such as fossil fuels, petroleum and wood. Cigarette and tobacco smoke also releases small quantities of naphthalene into the environment.
Exposure to naphthalene
Exposure is most likely to occur in an occupational setting. However, the general public may be exposed to naphthalene through inhalation of smoke from burning fossil fuels or wood, or from inhaling vehicle exhaust fumes. The general public may also be exposed to naphthalene by breathing in cigarette smoke. Its use in household preparations, such as mothballs, has been replaced, making exposure in the home less common.
How exposure to naphthalene can affect your health
The presence of naphthalene in the environment does not always lead to exposure. For it to cause any adverse health effects, you must come into contact with it. You may be exposed by breathing, eating or drinking the substance or by skin contact. Following exposure to any chemical, the adverse health effects you may encounter depend on several factors, including:
- the amount to which you are exposed (the dose)
- the way you are exposed
- the duration of exposure
- the form of the chemical
- if you were exposed to any other chemicals
Breathing fumes containing naphthalene, drinking solutions or swallowing solid naphthalene can cause nausea, vomiting, pain in the abdomen, diarrhoea, confusion, sweating, fever, fast heart rate, rapid breathing and may lead to convulsions, coma and possibly death.
About 3 to 5 days after severe exposure to naphthalene, blood may be present in the urine and may be dark brown in colour, caused by a breakdown of the red blood cells, which leads to kidney failure.
Skin contact with naphthalene can cause skin irritation and could possibly cause inflammation of the skin, with redness, swelling, pain and itching.
Exposure of the eyes to naphthalene may result in irritation and damage to the cornea and may lead to the formation of cataracts.
Naphthalene and cancer
The International Agency for Research on Cancer (IARC) has concluded that there is enough evidence in experimental animals, but not in humans that prolonged exposure to naphthalene can cause cancer. Therefore, they have classified naphthalene as possibly having the ability to cause cancer in humans.
Vulnerable people
People with a hereditary deficiency of glucose-6-phosphate dehydrogenase (G6PD) are particularly susceptible to naphthalene exposure.
Pregnancy and the unborn child
Available evidence does not indicate that exposure to naphthalene during pregnancy will have a direct effect on the unborn child. However, if the exposure to naphthalene causes the mother to become unwell this may affect the health of the unborn child.
Children
Children are more sensitive to the effects of naphthalene than adults.
What to do if you are exposed to naphthalene
You should remove yourself from the source of exposure.
If you have got naphthalene on your skin, remove soiled clothing (not above 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 naphthalene in your eyes, remove contact lenses, wash the affected area with lukewarm water for at least 10 to 15 minutes and seek medical advice.
If you have inhaled or ingested naphthalene, seek medical advice.
Additional sources of information
NHS.UK information on poisoning
UKTIS best use of medicines in pregnancy
The information contained in this document from the UKHSA Radiation, Chemicals, Climate and Environmental Hazards Directorate is correct at the time of its publication.
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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