Simazine (Princep) - Herbicide Profile 2/85
CHEMICAL name: 2-chloro-4,6-bis(ethylamino)-s-triazine (56)
TRADE name(S): Princep, Aquazine (58)
FORMULATION(S): Wettable powder (80%0, water dispersible granule
(90%; Caliber 90), liquifieds (4L), and granular
(4G). Aquazine for algae control in ponds (56).
TYPE: Triazine herbicide
BASIC PRODUCER(S): Ciba-Geigy Corp.
P.O. Box 11422
Greensboro, NC 27409
STATUS: General use
PRINCIPAL USES: Used for the control of most annual grasses and
broadleaf weeds in corn, established alfalfa, established
bermudagrass, cherries, peaches, citrus, caneberries, cranberries,
grapes, apples, pears, certain nuts, asparagus, certain
ornamental and tree nursery stock, and in turfgrass sod production. At
higher rates, it is used for nonselective weed control in industrial
areas (56). Simazine is also used for selective control of algae and
submerged weeds in ponds. It is approved for algae control in swimming
pools, large aquaria, ornamental fish ponds, fountains, and
recirculating water cooling towers (58).
Simazine applied preemergence to the weeds at dosage rates of 1 to
4 lbs. active ingredient per acre has controlled the following:
barnyardgrass hempnettle redroot pigweed
beggar-ticks jimsonweed Shepherdspurse
carpetweed knotwood smartweed
catchfly kochia sowthistle, common
chickweed, common lambsquarters stinkgrass
cocklebur nightshade stinkweed
corn spurry panicum, fall velvetleaf
crabgrass plantain water hemp
downy bromegrass puncture vine white cockle
Florida pusley purslane wild buckwheat
foxtail, green quackgrass wild mustard
foxtail, yellow quickweed wild oats
goosegrass ragweed, common witchgrass
groundsel ragweed, giant yellow rocket (24f)
Weeds controlled in alfalfa (for North and South Dakota, Minnesota,
Wisconsin, Nebraska, Kansas, Iowa, Michigan, and New York):
Downy brome (cheatgrass), henbit, wild mustard, chickweed, wild oats,
Knawel (German moss), alyssum, pepper grass, tansey mustard, pigweed,
speedwell, and seedlings of yellow rocket, white cockle, fanweed
(pennycress), dandelion, Russian thistle, shepherdspurse, and kochia.
Weeds not controlled:
Princep will not control dodder and established perennial and
biennial weeds such as dandelion, white cockle, quackgrass, cinquefoil,
wild carrot, dock, and certain other weeds (24g).
II. PHYSICAL PROPERTIES
MOLECULAR FORMULA: C7 H12 Cl N5 (62)
MOLECULAR WEIGHT: 201.7 (62)
PHYSICAL STATE: Colorless crystalline powder (pure compound) (62)
MELTING POINT: 225-227 C (decomp.) (pure compound) (62)
VAPOR PRESSURE: 810 nPa at 20 C (pure compound) (62)
SOLUBILITY: 5 mg/l water at 20 C (pure compound) (62)
III. HEALTH HAZARD INFORMATION
OSHA STANDARD: NA
NIOSH RECOMMENDED LIMIT: NA
ACGIH RECOMMENDED LIMIT: NA
A. ACUTE TOXICITY
DERMAL: LD50 = >10,200 mg/kg (rabbit, Princep 80W);
minimally irritating to the skin. Studies with
rabbits have shown that irritation to the skin was
barely perceptible 24 hrs. after exposure
(Princep 80W) (24e).
LD50 = >3100 mg/kg (rat), non-irritant to skin
of rabbits (62).
ORAL: LD50 = >5000 mg tech./kg (rat) (62)
LD50 = >15,380 mg/kg (rat, Princep 80W); in studies
with rats, no animals died from a single swallowed
amount of 15,380 mg/kg (Princep 80W) (24e).
INHALATION: LC50 = >1.0 mg/l air - 4 hours (rat); no higher
concentrations were possible with this material;
no animals died during this study (Princep 80W)
EYES: Slightly irritating on contact. Studies with
rabbits have shown that some redness and swelling of
the eyelids occurred (Princep 80W) (24e).
B. SUBACUTE AND CHRONIC TOXICITY:
In 2-yr. feeding trials NEL was: for rats 100 mg/kg diet (7 mg/kg
daily); for dogs 150 mg/kg diet (5 mg/kg daily) (62).
IV. ENVIRONMENTAL CONSIDERATIONS
Simazine is more highly adsorbed in muck or high clay soils than
in low organic or low clay content soils. The downward movement or
vertical leaching of simazine occurs at a rather low rate of speed,
probably due to the low water solubility of the compound and also
adsorption to the soil particles. Tests indicate that several months
after application the greatest amount of simazine remaining in the soil
is contained in the area near the soil surface. The compound has
little if any lateral movement in soils (24f).
Microbial breakdown is one of several processes involved in the
degradation of simazine. In soils, microbial activity possibly
accounts for decomposition of a significant amount of simazine. Under
normal climatic conditions, loss of simazine from soil by
photodecomposition and/or volatilization is considered insignificant
Approximate Residual Period: In regard to the soil residual activity
of simazine, results to date suggest that most rotational crops can be
planted and grown one year after an application of simazine at the
dosage rate recommended for the soil type; tillage practices such as
plowing and harrowing will reduce the possibility of adverse soil
residual effects. Adverse soil residual activity has been experienced
mainly in areas of extremely low rainfall or where rainfall has been
practically nonexistent following application of the compound. Oats
appear to be one of the most susceptible crops to the residual activity
of Simazine (24f).
V. EMERGENCY AND FIRST AID PROCEDURES
The chemical information provided below has been condensed
from original source documents, primarily from "Recognition and
Management of Pesticide Poisonings", 3rd ed. by Donald P. Morgan,
which have been footnoted. This information has been provided in
this form for your convenience and general guidance only. In
specific cases, further consultation and reference may be required
and is recommended. This information is not intended as a sub-
stitute for a more exhaustive review of the literature nor for the
judgement of a physician or other trained professional.
If poisoning is suspected, do not wait for symptoms to develop.
Contact a physician, the nearest hospital, or the nearest Poison
KNOWN OR SUSPECTED ADVERSE EFFECTS:
Some triazines are mildly irritating to skin,
eyes, and upper respiratory tract. Systemic toxicity is unlikely
unless very large amounts have been ingested (25).
SKIN CONTACT: Wash contaminated skin with soap and water (25).
INGESTION: Ingestions of small amounts (less than 10 mg/kg
body weight) occurring less than an hour before treatment, are probably
best treated by: Syrup of Ipecac, followed by 1-2 glasses of water.
Dose for adults and children over 12 years: 30 ml. Dose for children
under 12 years: 15 ml (25).
INHALATION: Remove from contaminated atmosphere. If symptoms
appear or person is unconscious, get medical attention (Princep 80W)
EYE CONTACT: Flush contaminated eyes with copious amounts of
fresh water for 15 minutes (25).
NOTES TO PHYSICIAN:
INGESTIONS of LARGE amounts (more than 10 mg/kg) occurring less than an
hour before treatment, should probably be treated by gastric lavage:
A. INTUBATE stomach and ASPIRATE contents.
B. LAVAGE stomach with slurry of ACTIVATED CHARCOAL IN 0.9% saline.
Leave 30-50 gm activated charcoal in the stomach before
C. SODIUM SULFATE, 0.25 gm/kg in tap water, as a cathartic.
CAUTION: Hydrocarbons (kerosene, petroleum distillates) are
included in some formulations of these chemicals.
Ingestion of very LARGE AMOUNTS may cause CNS
depression. In this case, IPECAC IS CONTRAINDICATED.
Also, gastric intubation incurs a risk of HYDROCARBON
PNEUMONITIS. For this reason observe the following
(1) If the victim is unconscious or obtunded and
facilities are at hand, insert an ENDOTRACHEAL TUBE
(cuffed, if available) prior to gastric intubation.
(2) Keep victim's head BELOW LEVEL OF STOMACH during
intubation and lavage (Trendelenburg, or left
lateral decubitus, with head of table tipped
downward). Keep victim's head turned to the left.
(3) ASPIRATE PHARYNX as regularly as possible to remove
gagged or vomited stomach contents.
INGESTIONS occurring MORE THAN an HOUR before treatment are probably
MAGNESIUM SULFATE, 0.25 gm/kg, as described above.
There are no specific antidotes for these chemicals. Because
manifestations of toxicity do occasionally occur in peculiarly
predisposed individuals, MAINTAIN CONTACT with victim for at least 72
hours so that unexpected adverse effects can be treated promptly (25).
VI. FIRE AND EXPLOSION INFORMATION
GENERAL: Not a combustible product. No hazardous decomposition
products. As in any fire, prevent human exposure to fire, smoke, fumes
or products of combustion. Evacuate nonessential personnel from the
area. Firefighters should wear impervious clothing such as gloves,
hoods, suits and rubber boots. Use of contaminated buildings, area and
equipment must be prevented until they are properly decontaminated
(Princep 80W) (24e).
EXTINGUISHER TYPE: Use standard organic chemical firefighting
techniques in extinguishing fires involving this material - use water,
dry chemicals, foam or carbon dioxide (Princep 80W) (24e).
Compatible with most other pesticides and fertilizers when used at
normal rates. Noncorrosive under normal use conditions (58).
VIII. PROTECTIVE MEASURES
STORAGE AND HANDLING: Keep this material out of the reach of children.
Containers must be stored in a cool, dry, well ventilated area. Store
away from foodstuffs. All food must be kept in a separate area away
from the storage/use location. Eating, drinking and smoking should be
prevented in areas where there is a potential for exposure to this
material (Princep 80W) (24e).
PROTECTIVE CLOTHING: Skin contact should be prevented through the use
of rubber gloves and clothing consistent with good pesticide handling
practice. Eye contact should be avoided through the use of chemical
safety glasses or goggles (Princep 80W) (24e).
IX. PROCEDURES FOR SPILLS AND LEAKS
IN CASE OF EMERGENCY, CALL, DAY OR NIGHT
PESTICIDE TEAM SAFETY NETWORK/CHEMTREC
Make sure all personnel involved in spill cleanup follow good
industrial hygiene practices.
Small spills can be handled routinely. Sweep up the material and
place in an appropriate chemical waste container. Seal container and
dispose of in an approved landfill. Wash the spill area with a strong
detergent and water. Flush the spill area with water to remove any
Do not reuse container. Destroy by burying in a safe place.
Disposal of material, spill residues, wash water, and containers must
be by methods consistent with local, state and federal health and
environmental regulations (Princep 80W) (24e).
X. LITERATURE CITED
24e. Ciba-Geigy Corporation, Agricultural Division. 1982. Safety
data sheet: Princep 80W. Greensboro, NC.
24f. Geigy Chemical Corporation. 1960. Herbicide technical
bulletin no. 60-1: simazine herbicides for agricultural
use. Ardsley, NY.
24g. Ciba-Geigy Corporation. 1973. Information sheet: Princep
for weed control in alfalfa. Greensboro, NC.
25. Morgan, D.P. 1982. Recognition and management of pesticide
poisonings, 3rd ed. U.S. Environmental Protection Agency,
Washington, DC. 120 pp.
56. Farm Chemicals Handbook, 70th ed. 1984. R. T. Meister, G. L.
Berg, C. Sine, S. Meister, and J. Poplyk, eds. Meister
Publishing Co., Willoughby, OH.
58. Weed Science Society of America, Herbicide Handbook Committee.
1983. Herbicide handbook of the weed science society of
America, 5th ed. Weed Science Society of America, Champaign,
IL. 515 pp.
62. The Pesticide Manual: A World Compendium, 7th ed. 1983. C.R.
Worthing, ed. The British Crop Protection Council, Croydon,
England. 695 pp.