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Atrazine

DESIGNATIONS

CAS No.: 1912-24-9
Registry name: Atrazine
Chemical name: 2-Chloro-4-ethylamino-6-isopropylamino-1,3,5-triazine
Synonyms, Trade names: 6-Chloro-N-ethyl-N'-(1-methylethyl)-1,3,5-triazin-2,4-diamine, 2-chloro-4-ethylamino-6-isopropylamino-s-triazin, Gesaprim
Chemical name (German):
Atrazin, 2-Chlor-4-ethylamino-6-isopropylamino-1,3,5-triazin
Chemical name (French):
Atrazine
Appearance:
colourless, crystalline solid

BASIC CHEMICAL AND PHYSICAL DATA

Empirical formula:

C8H14ClN5

Rel. molecular mass:

215.69 g

Density:

1.2 g/cm3

Boiling point:

not distillable

Melting point:

173-175C

Vapour pressure:

4 x 10-5 Pa

Solvolysis/solubility:

in water: approx. 70 mg/l; in ether: 12 g/l (20C); in methanol: 18 g/l (at 27C); in n-pentane: 36 mg/l (27C); in chloroform: 52 g/l (27C)

ORIGIN AND USE

Usage:
Atrazine is used as a selective herbicide e.g. for weed control in corn and asparagus, in the culture of sugarcane and pineapple and in winegrowing (also in combination with e.g. mecoprop). Additionally, it is used as a total herbicide on roads and public places as well as on uncultivated ground in combination with amitrol, bromacil, dalapon and growth promoters. Atrazine inhibits photosynthesis and other metabolic processes in plants.

Origin/derivation:
There are no natural sources of atrazine. It is produced from cyanuric acid chloride with ethylamine and isopropylamine. The reaction takes place successively in tetrachloromethane. All the atrazine produced is released into the environment.

Production figures:

World

90,000 t

(1976)

USA

40,000 t

(1976)

EU

750 t

(1978/79)

D

< 1,000 t

(1985)

 

1,164 t

(1987)

Toxicity

Mammals:

Rat

LD50 3080 mg/kg, oral

acc. PERKOW, 1985

LD50 >5600 mg/kg, dermal

acc. RIPPEN, 1992

LC50 > 710 mg/m3 (1h), inhalation

acc. PERKOW, 1985

Mouse

LD50 1750 mg/kg, oral

acc. PERKOW, 1985

Rabbit

LD50 750 mg/kg, oral

acc. PERKOW, 1985

LD50 7500 mg/kg, dermal

acc. PERKOW, 1985

Hamster

LD50 1000 mg/kg, oral

acc. RIPPEN, 1992

Aquatic organisms:

Rainbow trout

LC50 8.8 mg/l (96h)

acc. PERKOW, 1985

Perch

LC50 16 mg/l (96h)

acc. PERKOW, 1985

Carp

LC50 76 mg/l (96h)

acc. PERKOW, 1985

Green algae

EC50 0.055 mg/l (inhibition of growth)

acc. RIPPEN, 1992

EC0 0.030 mg/l (inhibition of cell division)

acc. RIPPEN, 1992

Plants:

Corn

>70% effect at 4.5 kg/ha

acc. RIPPEN, 1992

Lettuce

>70% effect at 0.5 kg/ha

acc. RIPPEN, 1992

Millet

35-70% effect at 1.6 mg/l

acc. RIPPEN, 1992

Soybean

35-70% effect at 1.1 mg/l

acc. RIPPEN, 1992

Wheat

35-70% effect at 4.3 mg/l

acc. RIPPEN, 1992

Characteristic effects:

Humans/mammals: The acute toxicity of atrazine for mammals is very low. In addition, there is hardly any resorption via the skin due to its low solubility. Atrazine does not irritate the skin or the eyes. It is easily resorbed after oral intake and within 24 hours, more than 50% is excreted via urine. During the passage, atrazine is completely metabolised mainly by way of oxidative dealkylation of the amino group and reaction of the chlorine atom with endogenic thiolic reagents. In animal experiments, mutagenic or teratogenic effects have not been discovered. Thus, in Germany, the substance is not classed as toxic.

ENVIRONMENTAL BEHAVIOUR

Soil:
The substance is characterised by a relatively high resistance to physical and chemical transformation. In addition, the low solubility in water and the low vapour pressure indicate a reduced mobility. Atrazine may be chemically hydrolysed forming the inactive hydroxyatrazine which in turn may be microbiologically decomposed. The half-life for hydrolysis is strongly dependent on the pH of the soil. In a neutral, slightly alkaline or slightly acid environment, atrazine is stable (half-life at pH 7-9: 10,000 days). Hydrolysis mainly takes place under alkaline or acid conditions (half-life at pH 3 or pH 11 3 months) [acc. KOCH, 1989].

Water:
Although atrazine is very stable and only slightly soluble in water, the contamination of groundwater has to be considered. In Germany, atrazine is classified in water hazard class 2.

ENVIRONMENTAL STANDARDS

Medium/
acceptor
Sector Country/organ. Status Value Cat. Remarks Source
Soil:   NL

G

0.05 m g/kg   Reference acc. TERRA TECH, 6/94
  NL

L

6 mg/kg   Intervention acc. TERRA TECH, 6/94
Water: Drinkw D

L

0.1 g/l   single substance acc. KOCH, 1989
Drinkw D

L

0.5 g/l   sum of pesticides acc. KOCH, 1989
Drinkw EC

L

0.1 g/l   single substance  
Groundw NL

G

0.0075 g/l   Reference acc. TERRA TECH, 6/94
Groundw NL

L

150 g /l   Intervention acc. TERRA TECH, 6/94
Air: Workp D

L

2 mg/m3 MAK   acc. RIPPEN, 1992
Workp SU

(L)

2 mg/m3 PDK   acc. AUER TECHNIKUM, 1988
Workp USA

(L)

5 mg/m3 TWA   acc. RIPPEN, 1992
Foodstuffs:
Mushrooms D

L

10 mg/kg     acc. PERKOW, 1985
Vegetable Corn D

L

1 mg/kg     acc. PERKOW, 1985
Corn D

L

0.5 mg/kg     acc. PERKOW, 1985
Vegetables D

L

0.1 mg/kg     acc. PERKOW, 1985
Asparagus CH

L

1 mg/kg     acc. PERKOW, 1985
Corn CH

L

0.1 mg/kg     acc. PERKOW, 1985

Assessment/comments

Because of its persistence and the hazard of contamination of groundwater and drinking water, the use of atrazine should be restricted as far as possible.


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