Dinitro-o-cresol (DNOC) is an organic compound with the structural formula CH3C6H2(NO2)2OH. [1] DNOC is a yellow solid with no smell. The taste of DNOC is not known. It dissolves slightly in water. [2]

Use [2,3]

DNOC was primarily used to protect fruit trees and other food crops from insect damage. In 1991, the United States EPA cancelled DNOC’s registration as a pesticide. Another less expensive chemical that is more effective in controlling pests is replacing DNOC. In the 1930s, DNOC was used in pills for reducing weight. It is no longer used for this purpose because of bad effects on health.

In the Environment [2]

  • Air: DNOC destruction in air from chemical reactions with other pollutants or from interaction with sunlight may be insignificant. It eventually returns from air to land and water by settling and washout by snow and rainwater. It is unknown how long DNOC stays in the air before it is fully removed.
  • Water: No known chemical reaction removes significant amounts of DNOC from water. In water, microorganisms may slowly break down DNOC. DNOC does not appreciably evaporate from water. Some of the DNOC sticks to particles present in water. This process partially transfers DNOC from water to the bottom sediment.
  • Soil: No known chemical reaction removes significant amounts of DNOC from soil. Microorganisms break down DNOC in soil. The loss of DNOC from soil by evaporation is not significant. DNOC has been found in groundwater from fields where it was applied. The level of DNOC in soil may decrease to half its original level in an estimated 14 days to 1 month or longer.

Sources & Routes of Exposure

Sources of Exposure [2,3]

People can be exposed to DNOC by breathing contaminated air, drinking contaminated water, or eating contaminated food. Other than in certain workplaces, levels of DNOC in the air have not been measured. However, the ambient level is expected to be very low. The levels of DNOC in drinking water and food also have not been detected. Certain people may be exposed to slightly higher levels of DNOC. People who live near sites containing DNOC wastes may be exposed primarily by breathing contaminated air. Children playing at or near these sites will be exposed by touching and eating soil if that soil contains DNOC. You may be exposed to DNOC if your work involves manufacturing, preparing, or using formulated DNOC products. You may be exposed if you work as a sprayer of DNOC. You also may be exposed to DNOC if your work involves incinerating waste containing DNOC or cleaning up sites contaminated with DNOC.

Routes of Exposure [4]

The major routes of exposure to DNOC are:

  • Inhalation,
  • Skin absorption,
  • Ingestion,
  • Skin and/or eye contact

Health Effects [3]

Acute Effects

  • Increased basal metabolic rates have resulted in humans following acute and chronic exposures to DNOC. Symptoms of toxicity from acute exposure include profuse sweating, increased pulse rate, increased respiratory rate, thirst, fatigue, lethargy, headache, nausea, appetite loss, malaise, collapse, coma and greenish-yellow pigmentation of the conjunctivae in humans. Yellow colouring of the hands, nails, and hair may also result.
  • Damage to the liver, kidney, and nervous system have been reported in humans following acute exposure.
  • DNOC is an uncoupler of oxidative phosphorylation, which accounts for its extreme acute toxicity.
  • Dermal contact may lead to local necrosis.
  • Acute animal tests in rats, mice, rabbits, and guinea pigs have demonstrated DNOC to have extreme acute toxicity from oral exposure and high acute toxicity from dermal exposure.

Chronic Effects

  • Chronic exposure results in the same symptoms of toxicity in humans as acute exposure.
  • Bilateral cataracts and blindness have been observed in individuals chronically exposed to DNOC by ingestion.
  • Respiratory, cardiovascular, gastrointestinal, and CNS effects in chronically exposed workers have been reported.
  • Decreased weight gain and food consumption have been observed in rats chronically exposed to DNOC by ingestion. Changes in the blood and urine, decreased liver enzyme activity, and changes in the absolute and relative organ weights (increased weights of the heart, brain, liver, kidney, spleen, adrenals, and thyroid and decreased weights of the thymus, uterus, ovaries, testes, and prostate gland) were also reported in rats; increased liver weight was described at all concentrations of exposure.
  • EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for DNOC.
  • ATSDR has established an intermediate oral minimal risk level (MRL) of 0.004 milligrams per kilogram body weight per day (mg/kg/d) based on neurological effects in humans. The MRL is an estimate of the daily human exposure to a hazardous substance that is likely to be without appreciable risk of adverse noncancer health effects over a specified duration of exposure. Exposure to a level above the MRL does not mean that adverse health effects will occur. The MRL is intended to serve as a screening tool.

Reproductive/Developmental Effects

  • No information is available on the reproductive or developmental effects of DNOC in humans.
  • DNOC had no teratogenic or embryotoxic effects in several animal studies, while chromosomal aberrations were reported in the foetuses of pregnant mice given DNOC by gavage.
  • One animal study reported that DNOC affected spermatogenesis, while another study did not find similar results.

Cancer Risk

  • No information is available on the carcinogenic effects of DNOC in humans or animals.
  • EPA has not classified DNOC for potential carcinogenicity.

Safety [5]

First Aid Measures

  • Eyes: In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Get medical aid immediately.
  • Skin: In case of contact, get medical aid immediately. Immediately flush eyes or skin with plenty of water for at least 15 minutes while removing contaminated clothing and shoes. Wash clothing before reuse. Destroy contaminated shoes.
  • Ingestion: If swallowed, get medical aid immediately. Only induce vomiting if directed to do so by medical personnel. Never give anything by mouth to an unconscious person.
  • Inhalation: If inhaled, get medical aid immediately. Remove victim to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.

Exposure Controls & Personal Protection

Engineering Controls

Facilities storing or utilising DNOC should be equipped with an eyewash facility and a safety shower. Use adequate general or local exhaust ventilation to keep airborne concentrations below the permissible exposure limits.

Personal Protective Equipment

The following personal protective equipment is recommended when handling DNOC:

  • Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA’s eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166.
  • Skin: Wear appropriate protective gloves to prevent skin exposure.
  • Clothing: Wear appropriate protective clothing to prevent skin exposure.
  • Respirators: A respiratory protection program that meets OSHA’s 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard EN 149 must be followed whenever workplace conditions warrant respirator use.

Regulation [2,6,7]

United States

OSHA: The United States Occupational Safety & Health Administration has set the following Permissible Exposure Limit (PEL) for DNOC:

  • General Industry: 0.2 mg/m3 (Skin)
  • Construction Industry: 0.2 mg/m3 TWA (Skin)

ACGIH: The American Conference of Governmental Industrial Hygienists has established a Threshold Limit Value (TLV) for DNOC of 0.2 mg/m3 TWA (Skin)

NIOSH: The National Institute for Occupational Safety and Health has set a Recommended Exposure Limit (REL) for DNOC of 0.2 mg/m3 TWA(skin)

EPA: The Environmental Protection Agency has listed DNOC as a hazardous air pollutant. Federal regulations limit the amount of DNOC that factories can release into wastewater. EPA requires industries to report releases or spills of 10 pounds or more.


Safe Work Australia: Safe Work Australia has set a time weighted average (TWA) concentration of 0.2 mg/m3 for DNOC for an 8-hour workday.