Sulfur is an element that exists in nature and can be found in soil, plants, foods, and water.¹ Some proteins contain sulfur in the form of amino acids.² Sulfur is an essential nutrient for plants.³ Sulfur can kill insects, mites, fungi, and rodents. Sulfur has been registered for use in pesticide products in the United States since the 1920s.⁴

Products containing sulfur can be dusts, wettable powders, liquids, or fumigant gas cartridges.⁴ They are used in field crops, root crops, tree fruits, nuts, berries, vegetables, ornamentals, and turf. They are also used in outdoor residential areas and on food and non-food crops. Non-food use sites include pets, livestock, and livestock quarters.⁴

There are over 200 active products containing sulfur on the market in the United States.⁵ Some have been approved for use in organic gardening.⁶ Non-pesticide products containing sulfur are used as soil amendments or fertilizers.⁷

Sulfur kills fungi on contact.⁸ The way sulfur works is not completely understood yet. Some researchers believe sulfur may react with plants or fungi to produce a toxic agent.⁹ However, the main theory is that sulfur enters fungi cells and affects cell respiration.¹⁰

Sulfur can kill insects if they touch it or eat it.⁶ It disrupts their normal body function, altering their ability to produce energy.¹³ Sulfur in gas cartridges, after ignited and placed in a burrow, releases toxic gases that suffocate burrowing animals.⁷

Sulfur is present in food and we may be exposed to it in our regular diet.¹² You can also be exposed if you are applying sulfur dusts or sprays and you get it on your skin, in your eyes, or breathe it in. This can also happen if you get some on your hands and eat or smoke without washing your hands first.

You can limit your exposure to sulfur by following all label instructions carefully.

Sulfur is low in toxicity to people. However, ingesting too much sulfur may cause a burning sensation or diarrhea. Breathing in sulfur dust can irritate the airways or cause coughing. It can also be irritating to the skin and eyes. Blurred vision has also been reported.¹³

If animals eat too much sulfur, it may be toxic and can be fatal. Signs of poisoning in animals include problems to the stomach and intestines, effects on the lungs, and neurologic disorders.¹⁴ Sulfur in excess can cause brain cell death, resulting in brain damage. Signs associated with brain damage can include blindness, incoordination, seizures, death, and others.¹⁵ See the fact sheet on pets and pesticide use for more information about reducing risks to pets.

Burning sulfur creates sulfur dioxide, a gas. If inhaled, coughing, shortness of breath, sore throat, and labored breathing, has been reported. Eye irritation has also been reported.¹⁶

Sulfur is essential for humans, animals, and plants. When it enters our body it can be incorporated into tissues like skin and cartilage. It is also found in some proteins and vitamins.¹⁷

When sulfur gets on intact skin, most of it does not get into the bloodstream. However, it can be absorbed into skin itself. In one study, sulfur was applied to the skin and was detectable from 2 to 8 hours afterwards. It was undetectable after 24 hours. In another study, sulfur was applied for 8 hours to the skin of four volunteers. Sulfur was found in urine 2 hours later and after 6 hours it reached its maximum. Researchers found that 1% of sulfur was taken into the body after 20 hours. About half of this was removed from the body in urine.¹⁸

Sulfur is common in water and soil and daily exposure to sulfur is expected. The US Environmental Protection Agency (US EPA) concluded that there are no known cancer risks related to sulfur. Sulfur is not known to alter or damage genes.¹²

Prolonged or repeated skin contact may cause rashes or calluses.¹² Breathing sulfur over the long-term may irritate the nose and the respiratory tract, resulting in chronic bronchitis.¹³

The EPA has concluded that there are no known risks to reproduction or child development from sulfur.¹²

While children may be especially sensitive to pesticides compared to adults, there are currently no data to conclude that children have increased sensitivity specifically to sulfur. However, young children may act in ways that put them at greater risk of being exposed.19 For example, they may spend more time near the ground. They may also be more likely to place their hands in their mouths after touching treated plants or surfaces.

Sulfur naturally occurs in the environment. Elemental sulfur applied to the soil will be incorporated into the natural sulfur cycle.⁷

Sulfur doesn’t dissolve well in water. Therefore, drift or runoff to water bodies it is not expected to impact aquatic life. Sulfur drift to areas close to a treated field can injure sulfur-sensitive plants.⁷

Sulfur has shown to be practically non-toxic to bobwhite quail, bluegill sunfish, rainbow trout, water fleas, and mysid shrimp. It is also practically non-toxic to the honeybee.⁷