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Sulfur

Publication Date: 9/95

TRADE OR OTHER NAMES

The active ingredient sulfur is found in a variety of commercial fungicides. Some trade names for products containing sulfur include Cosan, Crisazufre, Hexasul, Sulflox, Tiolene, and Thiolux (3, 4). Crisazufre and Sulflox are marketed outside the U.S. (3). The compound may be used in combination with other fungicides that include nitrothal-isopropyl, rotenone, thiabendazole, mancozeb, sodium pentaborate, urea, carbendazim + maneb, and cymoxanil + copper oxychloride (1).

REGULATORY STATUS

Sulfur is a general use pesticide (GUP). Check with specific state restrictions which may apply. Products containing the active ingredient sulfur must bear the Signal Word "Caution" on their label (3).

INTRODUCTION

Sulfur is a non-systemic contact and protectant fungicide with secondary acaricidal activity. It is used for control of brown rot of peaches, powdery mildew of apples, gooseberries, hops, ornamentals, grapes, peaches, strawberries, sugar beets, apple scab, gall mite on blackcurrant, peanut leafspot, mildew on roses, mites on beans, carrots, lucerne, melons, and tomatoes, etc. (1, 2, 3). Sulfur is also used on livestock and in agricultural premises (4).

Sulfur comes in wettable, flowable and colloidal formulations (1). Compatibility with other products is considered good. Numerous mixed products with insecticides and fungicides are manufactured. For reasons of phytotoxicity, mixing sulfur with oils should be avoided (1, 3). Inert material is usually added during manufacture to prevent electrostatic "balling" (2).

Sulfur has been known and used as a pesticide since very early times, and has been registered for pesticidal use in the United States since the 1920s (8). It was first used around 1880 (4). Currently, sulfur is registered in the U.S. by EPA for use as an insecticide, fungicide, and rodenticide on several hundred food and feed crop, ornamental, turf and residential sites. It is also used as a fertilizer or soil amendment for reclaiming alkaline soils. Sulfur is applied in dust, granular or liquid form, and is an active ingredient in nearly 300 registered pesticide products (8).

Sulfur in its elemental reduced or oxidized forms represents approximately 1.9% of the total weight of the earth. The sulfates and sulfides are common in their various mineral forms. Most aquatic and terrestrial environments are high in sulfur, sulfur-deficient environments being quite rare in nature (9). Sulfur is considered non-corrosive and may cause tarnishing of some metals (1).

TOXICOLOGICAL EFFECTS

ACUTE TOXICITY

Sulfur is known to be of low toxicity, and poses very little if any risk to human and animal health (1, 8). Short-term studies show that sulfur is of very low acute oral toxicity and does not irritate the skin (it has been placed in EPA Toxicity Category IV, the least toxic category, for these effects). Sulfur also is not a skin sensitizer. However, it can cause some eye irritation, dermal toxicity and inhalation hazards (8).

When taken orally, it has a mild laxative action (1). It may cause irritation of skin and the mucous membranes. Sulfur is considered a skin and eye irritant (1, 2, 3, 4). Acute exposure inhalation of large amounts of the dust may cause catarrhal inflammation of the nasal mucosa which may lead to hyperplasia with abundant nasal secretions. Trachiobronchitis is a frequent occurrence, with dyspnea, persistent cough and expectoration which may sometimes be streaked with blood (5).

Sulfur was reported to have a rat oral LD50 of greater than 5,000 mg/kg (3, 10); and greater than 8,437 mg/kg (5). Another source reported an acute oral LD50 of greater than 5,000 mg/kg for 51.1%, 97%, and 98% sulfur. Also, there were no deaths of rats fed 98% sulfur at a single dose of 5,000 mg/kg (6). The intravenous rat LDlo (Lethal dose, low. The lowest dose which causes death in test animals.) was 8 mg/kg (5). The dermal LD50 for rats was greater than 5,000 mg/kg (3). The acute inhalation LC50 for 98% sulfur in rats is greater than 2.56 mg/l; and greater than 5.74 mg/l for 80 % sulfur (6).

The oral LDlo for sulfur in rabbits was 175 mg/kg (5). The acute dermal LD50 in rabbits was greater than 2,000 mg/kg at 51.1%, 97%, and 98% sulfur. Also, there were no deaths of rabbits fed 98% sulfur at a single dose of 2,000 mg/kg (6, 10). A rabbit eye irritation test indicated all irritation had cleared 6 days after 98% sulfur was administered (6). The intraperitoneal LDlo was 55 mg/kg for sulfur in guinea pigs (5).

CHRONIC TOXICITY

Chronic exposure to elemental sulfur at low levels is generally recognized as safe. Epidemiological studies show that mine workers exposed to sulfur dioxide throughout their lives often had eye and respiratory disturbances, chronic bronchitis and chronic sinus effects. However, no known risks of oncogenic, teratogenic, or reproductive effects are associated with the use of sulfur. Also, sulfur has been shown to be non-mutagenic in microorganisms (8).

Repeated or prolonged exposure to dust may cause irritation to the mucous membranes. Bronchopulmonary disease may occur which, after several years, may be complicated by emphysema and bronchiectasis. Early symptoms in sulfur miners often include upper respiratory tract catarrh, with cough and expectoration which is mucoid and may even contain granules of sulfur. Asthma is a frequent complication. The maxillary and frontal sinuses may be affected; involvement is usually bilateral and pansinuitis may occur (5).

Reproductive Effects

There are no known risks of reproductive hazards associated with sulfur (8, 9).

Teratogenic Effects

There are no known risks of teratogenic hazards associated with sulfur (8, 9).

Mutagenic Effects

No information currently available.

Carcinogenic Effects

There are no known risks of carcinogenic/oncogenic effects associated with the use of sulfur (5, 8).

Organ Toxicity

Pulmonary function may be reduced. Radiological examinations have revealed irregular opacities in the lungs and occasionally nodulation has been reported, but not true nodular fibrosis (5).

Fate in Humans and Animals

No information currently available.

ECOLOGICAL EFFECTS

Effects on Birds

Sulfur is considered non-toxic to birds (7). The 8-day dietary LC50 for bobwhite quail is reported to be greater than 5,620 ppm in a study using a 95% sulfur wettable powder formulation (9). In studies on ecological effects involving bobwhite quail, sulfur has been shown to be practically non-toxic to the species tested (8).

Effects on Aquatic Organisms

The 96-hour LC50 values for two fish species, bluegill sunfish and rainbow trout, are greater than 180 ppm in a study using a 99.5% sulfur dust formulation. The 48-hour LC50 for daphnia and the 96-hour LC50 for mysid shrimp is reported to be greater than 5,000 and 736 ppm, respectively, in a study using 90% sulfur (9, 10). In studies on ecological effects involving two fish species, daphnia, and mysid shrimp, sulfur has been shown to be practically non-toxic to the species tested (1, 3, 7, 8).

Effects on Other Animals (Nontarget species)

Sulfur is considered non-toxic to bees (1, 3, 7). In studies on ecological effects involving honeybees, sulfur has been shown to be practically non-toxic to the species tested. Thus, although there is potential for non-target organisms to be exposed to sulfur, little hazard to these species is expected to result (8).

Two beneficial insect studies demonstrated that sulfur (98% dust and 92% wettable powder) is low in toxicity to the honeybee through contact and ingestion (9).

ENVIRONMENTAL FATE

Breakdown of Chemical in Soil and Groundwater

Sulfur is a component of the environment, and there is a natural cycle of oxidation and reduction reactions which transforms sulfur into both organic and inorganic products. Sulfur in the form of sulfate constitutes about 0.1% of U. S. soils. Elemental sulfur is slowly converted to sulfate in soil by the action of autotrophic bacteria. Elemental sulfur leaches in soil as sulfate at a slow rate. About 3-6% of the sulfur (formulation and purity unspecified) applied at 56 kg/Ha leached through lysimeters of loam soil (soil depth unspecified) as a result of 40 inches of rain over a six-month period. After two years, 23-29% of the applied sulfur had leached (10).

Breakdown of Chemical in Surface Water

No information currently available.

Breakdown of Chemical in Vegetation

There is slight oxidation of sulfur to the volatile oxide. Primarily microbial reduction in and on plants; partial incorporation into physiological substances (1). Sulfur may cause plant injury when used at summer temperatures (3). Injury has been reported on apricots, raspberries, cucurbits and certain other "sulfur-shy" plants (4).

PHYSICAL PROPERTIES AND GUIDELINES

Physical Properties:

CAS No.: 7704-34-9 (1, 3)
Chemical name: Sulfur
Chemical Class/Use: fungicide, acaricide (1)
Solubility in water: Practically insoluble in water (1, 2)
Solubility in other solvents: Readily soluble in carbon disulphide. Very slightly soluble in ether, petroleum ether, toluene, acetone, chloroform, and alcohol; more readily soluble in hot benzene, acetone, carbon disulfide, carbon tetrachloride, liquid ammonia, and methylene iodide (1, 2, 5)
Melting point: 114.5-115 degrees C (1, 3, 7); 235 degrees F (5)
Boiling point: 444.6 degrees C (1); 832 degrees F (5)
Flashpoint: 405 degrees F (207 degrees C) (5)
Vapor pressure: 5.3 x 10 to the minus 6 mbar at 30.4 degrees C; 8.6 x 10 to the minus 5 mbar at 59.4 degrees C (1, 2). 1 mmHg @ 184 degrees C (5). 3.96 x 10 to the minus 6 mmHg at 30.4 degrees C (7)

BASIC MANUFACTURER

Various manufacturers

Review by Basic Manufacturers:

Comments solicited: October, 1994
Comments received:

REFERENCES

  1. The Agrochemicals Handbook. 1983. The Royal Society of Chemistry, The University, Nottingham, England.
  2. Worthing, C. R. (ed.). 1983. The Pesticide Manual: A World Compendium. Seventh edition. Published by The British Crop Protection Council.
  3. Farm Chemicals Handbook. 1994. Meister Publishing Co. Willoughby, OH.
  4. Thomson, W. T. 1992. Agricultural Chemicals. Book II: Herbicides. Thomson Publications, Fresno, CA.
  5. OHS Database. 1993. Occupational Health Services, Inc. 1993 (August) MSDS for Sulfur. OHS Inc., Secaucus, NJ.
  6. U.S. Environmental Protection Agency. 1988. Office of Pesticides. TOX Oneliners -- Sulfur. August, 1988.
  7. Pesticide Management and Education. An on-line pesticide information database in CENET, Cornell Cooperative Extension Network. Cornell University, Ithaca, NY.
  8. U.S. Environmental Protection Agency. May, 1991. Reregistration Eligibility Document Facts: Sulfur. US EPA, Pesticides and Toxic Substances, Washington, DC.
  9. U.S. Environmental Protection Agency. May, 1991. Reregistration Eligibility Document (RED): Sulfur. US EPA, Office of Pesticide Programs, Washington, DC.
  10. U.S. Environmental Protection Agency. December, 1982. Sulfur Pesticide Registration Standard, L. Rossi, et al. US EPA, Office of Pesticides and Toxic Substances, Washington, DC.