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Dinitro-o-cresol

DESIGNATIONS

CAS No.: 534-52-1
Systematic name: Dinitro-o-cresol
Chemical name: 2-Methyl-4,6-dinitrophenol
Synonyms, Trade names: 4,6-Dinitro-o-cresol, DNOC, DNC, Detal, Etzel, fruit-tree carboline
Chemical name (German): Dinitro-o-kresol, 2-Methyl-4,6-dinitrophenol
Chemical name (French):
Dinitro-o-crsol
Appearance:
yellow powder or crystals with bitter taste

BASIC CHEMICOPHYSICAL DATA

Empirical formula: C7H6N2O5
Rel. molecular mass: 198.14 g
Boiling point: (decomposition)
Melting point: 86-86.9C
Vapour pressure: 6.5 x 10-3 Pa at 25C
Flash point: limited combustibility
Solvolysis/solubility: in water: slightly soluble 125 ppm (at 25C);
in acetone: 100.6 g/100 g;
in ethanol: 4.3 g/100 g;
in benzene: 37.5 g/100 g;
in chloroform: 37.2 g/100 g;
soluble in diethylether, methanol, petroleum ether, carbon tetrachloride

ORIGIN AND USE

Usage:
DNOC is a selective herbicide used in the cultivation of grain, hops, vines and fruit (insecticide, acaricide, with fungicidal secondary effects).

Origin/derivation:
DNOC is only produced synthetically. Commercially available preparations contain formulations of the alkali, ammonia, or amine salts of DNOC which are normally highly soluble in water.

Toxicity

Humans: LD 0.35-3.0 g acc. DFG, 1986
Mammals:
Rat: LD50 25-85 mg/kg, oral acc. DFG, 1986
LD50 28.5 mg/kg, intraperitoneal acc. DFG, 1986
LD50 23.1-26.1 mg/kg, subcutaneous acc. DFG, 1986
Mouse: LD5020.0 mg/kg, oral acc. DFG, 1986
LD50 21.5-27.3 mg/kg, subcutaneous acc. DFG, 1986
LD50 1,000 mg/kg, cutaneous acc. DFG, 1986
LD50 24-26 mg/kg, intraperitoneal acc. DFG, 1986
Guinea pig: LD100 500 mg/kg, cutaneous acc. DFG, 1986
Dog: LD50 15 mg/kg, intravenous acc. DFG, 1986
LD50 10-23.5 mg/kg, intraperitoneal acc. DFG, 1986
Aquatic organisms:
American minnow: 1.5-2 mg/l lethal (6 h) acc. DVGW, 1988
Stickleback: 3 mg/l lethal acc. DVGW, 1988
Water flea: EC50 0.013 mg/l acc. DVGW, 1988
Blue algae: EC10 0.15 mg/l acc. DVGW, 1988
Green algae: EC10 13 mg/l acc. DVGW, 1988

Characteristic effects:

Humans/mammals: DNOC is a powerful, cumulative-action poison which can even prove fatal. Absorption is primarily by way of the lungs, but also via the gastro-intestinal tract and through the skin. Assimilated DNOC is only slowly excreted.

The first symptoms of poisoning are an increase in body temperature (high ambient temperatures enhance the severity), sweating, rapid breathing and accelerated pulse, extreme thirst, painful colics, diarrhoea and nausea. Typical symptoms of the effects on the central nervous system are euphoria to be followed by dizziness, possible collapse, anxiety, unrest, disorientation, loss of consciousness and terminal spasms.

Chronic poisoning takes the form of headaches, fatigue and noticeable weight loss. There is also damage to the heart, liver and kidneys. Liver damage is encountered primarily in the case of oral intake.

Plants: The effect on plants is based on the separation of cell respiration and oxidative phosphorylation.

ENVIRONMENTAL BEHAVIOUR

Water:
Despite the fact that the solubility in water is extremely low, surface water may be polluted by the elution of soil treated with DNOC. It is more harmful to plankton and microorganisms than to fish. Threshold concentration for water fleas is 3 mg/l, for mosquitoes 500 mg/l.

The toxicity of DNOC solutions is highly dependent on the pH. Acid solutions are more toxic than alkaline solutions (DFG, 1986).

Soil:
DNOC is highly mobile in soil and is only subject to slow microbial degradation. Most soil organisms are not adversely affected by DNOC; CO2 production is not impaired; the effect on microarthropodes (e.g. mites) and earth worms is however lethal.

Degradation, decomposition products:
Numerous metabolites have been found in the organism, some of which have a detoxifying effect, whereas others are even more toxic than DNOC itself (e.g. 6-amino-4-nitro-o-cresol or 4,6-diamino-o-cresol). There are no data available metabolites in plants and soil.

DNOC can be traced in soil for a period of up to 14 weeks (acc. DFG, 1986).

Food chain:
There is evidence of residues in parts of plants.

ENVIRONMENTAL STANDARDS

Medium/ acceptor Sector Country/ organ.

Status

Value Cat. Remarks Source
Water: Surface EC

(L)

0.001 mg/l   All pesticides1) acc. DVGW, 1988
Surface EC

(L)

0.0025 mg/l   All pesticides2) acc. DVGW, 1988
Surface EC

(L)

0.005 mg/l   All pesticides3) acc. DVGW, 1988
Drinkw EC

(L)

0.1 g/l     acc. DVGW, 1988
Drinkw FRG

L

0.1 g/l     acc. DVGW, 1988
Air: Workp FRG

L

0.2 mg/m3 MAK   DFG, 1989
Workp SU

(L)

0.05 mg/m3     acc. KETTNER, 1979
Workp USA

(L)

0.2 mg/m3 TWA   ACGIH, 1986
Foodstuffs:   FRG

(G)

0.01 ng/kg.d   Provisional DTA acc. DFG, 1986

Notes:

DNOC cannot be used as an insecticide in the Federal Republic of Germany in water catchment areas. Its use as a herbicide is banned in water protection zones I and II. Use in the immediate vicinity of stretches of water is forbidden.
1) Mandatory value for simple physical treatment and sterilisation
2) Mandatory value for normal physical and chemical treatment and sterilisation
3) Mandatory value for physical and refined chemical treatment, oxidation, adsorption and sterilisation

Assessment/comments

DNOC has an extremely high acute toxicity and represents a particular hazard. The substance is readily absorbed by the lungs and through the skin. Thus protective measures are required during application. The use of DNOC near large areas of water should particularly be avoided.


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