Simazine (Princep) - EXTOXNET Profile 12/88
USE: Simazine is a triazine herbicide. It is used to kill broad-leaved
weeds and grasses before they emerge in deep rooted crops. It is also
used to control vegetation and algae in farm ponds and fish hatcheries
(5). Other uses include control of algal growth in swimming pools,
fountains, ornamental fish ponds and recirculating water cooling towers.
Oral: (Eating or Drinking). Simazine has low oral toxicity(5).
A reported LD50 (the amount of chemical that will kill 1/2 of the
animals) for animals fed simazine is:
1. rabbits = 5000 mg/kg (NIOSH RTECS Online File # 83/8112).
Dermal: (Skin). Large amounts of simazine may cause dermatitis
(rashes). This kind of exposure may be gotten in manufacturing settings
(6). Normally, simazine has very low toxicity through the skin(5).
Inhalation: (Breathing). No information found.
Eye: No information found for humans. In rabbits, 80 mg of
simazine produced irritation in the eye (NIOSH RTECS Online File #
Acute symptoms in Humans: (Symptoms resulting from a single
exposure). The triazines disturb energy metabolism (thiamine and
riboflavin functions). Toxicity symptoms include:
1. difficulty in walking;
2. tremor, convulsions, paralysis;
3. cyanosis, slowed respiration;
4. miosis (pin point pupils);
5. gut pain, diarrhea;
6. impaired adrenal function(14).
Simazine is considered to be moderately toxic. It is possible that
0.5-5 g/kg ( between one ounce and one pint, or one pound) would kill a
70 kg (150 pound) person if eaten(19).
Reproductive Effects/Teratogenicity: (Effects on the ability to
have Children or on the Unborn Child itself). No information found.
Mutagenicity: (Effects on Chromosomes, or Genes, that may be
passed on to ones Children. These are usually bad.) No information
Carcinogenicity: (Effects that result in Tumor Growth). Simazine
is a possible carcinogen(14).
Organ Toxicity: (Effects that harm any body organs, such as the
Heart, Liver, Kidneys, or Lung). No information found for man. Sheep
(a sensitive species) show liver damage (mostly), as do rats(6). The
difference is that the rat's liver adapts to the simazine, and the
sheep's do not.
Fate in Humans (and animals): (What happens to the chemical in the
body). Information on the absorption and distribution of simazine was
not found. It does stimulate (induce) its own breakdown in the liver
(6). Some accumulation occurs in the fat(14). This indicates that
simazine is probably fairly well absorbed from the skin, lungs and gut.
Anywhere from 67-97% of the simazine in the body is excreted through the
urine within 24 hours.
Non-target Toxicity: (Harmful effects on things other than what
the chemical was intended for).
Aquatic: (Effects on water- dwelling life). Simazine has very low
toxicity to all aquatic species reviewed(5, 8). The LC50 (lethal
concentration for 50% of the exposed animals) for trout exposed to
simazine is 100 mg/L/96 hours (Hdbk Acute Tox. Chem. Fish and Aqua.
Terrestrial: (Effects on land- dwelling life). Mammals tend to be
insensitive to simazine(8), except for sheep(6). Birds are very
tolerant(5, 8). Simazine is almost non-toxic to bees(5, 8). The LC50
for 10 day old mallards and pheasants is more than 5000 ppm (Lethal
Diet Tox. Environ. Poll. Birds. 1975).
Bioaccumulation: (The build-up of the chemical either in the
environment or in a single living thing). Plants that are sensitive to
simazine accumulate it unchanged(2). It is possible that livestock or
wildlife grazing on these plants could then be poisoned. No other
information was found.
Biomagnification: (The build-up in living things of the chemical.
The level of build-up is determined by the diet. Vegetarians will have
less chemical than insect eating animals. The insect eaters will have
less chemical than the meat eaters). No information found.
Dissipation, Degradation and Persistence: (How the chemical is
broken down in the environment, and how long that takes). Simazine
tends to be fairly persistent. Residual activity remains for 2-7 months
(2-4 kg/HA) after application. Simazine adsorbs to clays and mucks.
Crops (half-life, carry over): It is not recommended that crops
be planted the same season as application. It is possible that the
desired crop plants will be injured by the simazine that carried over
(Osol. Remington's Pharm. Sci. 15th Ed. 1975).
Water: No information found.
Air: No information found.
Metabolism (soil microbes, plants, etc.): Plants absorb simazine
through their roots(2). It acts to inhibit photosynthesis(8).
Resistant plants readily metabolize simazine to possibly mutagenic by-
products (Menzie. Metab. Pesticides. 1974, 2, Environ. Health
Perspect. 27:45. 1978).
Potential for Groundwater Contamination: Simazine may leach
through the soil to the groundwater. Labels on containers of simazine
are required to include information about the possibility of groundwater
Simazine is compatible with most pesticides and fertilizers when
Simazine is very stable for several years of shelf life(2). It is
also stable to natural light and extremes of temperature(2).
CAS # 122-34-9
Solvent T degrees(degrees Celsius) Solubility
Chloroform 20 900 ppm*(1)
Light petroleum " 2 ppm(6)
Methanol " 400 ppm(6)
N-pentane 25 3 ppm(2)
Water 20 3.5 mg/L(5)
* Key: ppm = Parts per million
Boiling point: Not reported
Melting point: 225-227 degrees C(2).
Flash point: None reported.
Vapor pressure: 6.1 x 10 to the minus 9 mm Hg at 20 degrees C(5).
Oil: water partition coefficient: None reported.
Odor: None reported.
Density: 1.302 g/cubic centimeter(7).
1. Farm Chemicals Handbook. Ed by R.T. Meister. Meister Publishing
Co., Willoughby, OH. 1987.
2. Herbicide Handbook of the Weed Science Society of America. 5th Ed.
WSSA Herbicide Handbook Committee. WSSA, Champaigne, IL. 1983.
3. EPA-SAB-74-001 Herbicide Report Chemical Analysis, Environmental
Effects, Agriculture and Other Applied Uses. Hazardous Materials
Advisory Committee. EPA. May 1974.
4. Handbook of Toxicity of Pesticides to Wildlife. Richard Tucker.
USDI Fish and Wildlife Service. 1970.
5. The Pesticide Manual. 8th Ed. Ed.by C.R. Worthing. British Crop
Protection Council. 1987.
6. Pesticides Studied in Man. Wayland Hayes, Jr. Williams and
Wilkins, Baltimore MD. 1982.
7. Herbicides. 2nd Ed. Vols 1,2. Kearney. 1975.
8. The Agrochemicals Handbook. The Royal Society of Chem. 1983.
9. Crop Protection Chemicals Reference. 2nd Ed. Chemical and
Pharmaceutical Press. 1986.
10. Catalog of Teratogenic Agents. Thomas Shepard. John Hopkins
University Press. 1973.
11. Chemically Induced Birth Defects. James Schardein. Marcel Dekker.
12. Suspected Carcinogens. A subfile of the registry of toxic effects
of chemical substances. US Dept. of Health, Education and Welfare.
13. DOT. Emergency Response Guidebook. 1984.
14. Pesticides and Human Health. Hallinbeck & Cunningham-Burns.
15. First Aide Manual for Chemical Accidents. Lefevre. 1980.
17. Dangerous Properties of Industrial Materials. 4th Ed. Sax. 1975.
18. Toxicology 2nd Ed. Casarett and Doull. 1980.
19. CTCP 5th ED. Gosselin. 1984.
20. National Fire Prevention Association (NFPA). Fire Protection
Guide. Hazardous Materials. 1978.
21. Recog. and Manag. Pest Poisonings. Morgan. 1982.
22. Merck Index 9th Ed. 1976.
23. Handbook of Analytical Toxicology. Sunshine. 1969.
DISCLAIMER: The information in this profile does not in any way replace
or supersede the information on the pesticide product label/ing or other
regulatory requirements. Please refer to the pesticide product