2,2-Dichloropropionic acid

Description

Dalapon is a commonly used herbicide for the control of annual and perennial grasses in croplands. The US Environmental Protection Agency (EPA) has listed dalapon as a general use pesticide and categorized dalapon as a Class II toxic agent (moderately toxic). As such, any product that contains dalapon would be labeled with ‘warning.’ The moderate toxicity associated with dalapon is confined primarily to workers around dalapon and those individuals who are applying dalapon. Contact with the herbicide can be caustic to human skin, damaging to the conjunctiva of the human eye, and irritating/damaging to the upper respiratory system of humans. When used to control grasses in cropland as well as noncropland, dalapon is distributed via either aerial or ground equipment for foliage application. Some of the common croplands that have benefitted from dalapon application include corn, potatoes, legume crops, citrus, fruit, and nut trees. It is used extensively in the western United States to control a variety of grasses such as Bermuda, Johnson, Crab, and Quack grasses. Dalapon is translocated to the roots where it acts as a growth regulator. Although highly soluble with the ability to readily move through the environment, dalapon is relative safe and instances of dalapon intoxication are rare. The primary sources of toxicity are contact with the sodium or magnesium salt of dalapon, which is an irritant to the eyes, skin, and respiratory system. Cases of elevated levels of dalapon in drinking water or groundwater have also been rare, and little toxicity has been reported following dalapon exposure in water. Individuals who were exposed to high levels for extended periods of time can experience kidney dysfunction. Collectively, dalapon is a relatively safe herbicide for the control of many annual and perennial grasses.

Chemical Properties

clear yellow liquid

Uses

Dalapon is used as an herbicide primarily to control annual and perennial grasses, including Bermuda grass and Johnson grass. Use of dalapon on food crops is primarily with sugarcane and sugar beets. Dalapon is also used on fruits, potatoes, carrots, asparagus, alfalfa, and flax, and in forestry, home gardening, and to control reed and sedge growth in aquatic environments.

Uses

Herbicide marketed as the sodium salt or a mixture of the sodium and magnesium salts used to control grasses in a wide variety of crops and in a number of noncrop applications, such as along drainage ditches and railroads and in industrial areas.

Uses

Dalapon is used primarily for the selective control of annual and perennial grass weeds in cropland and noncropland. Dalapon is also used as a selective aquatic herbicide. It is acidic in nature and are not strongly sorbed by soils, and reported to be rapidly degraded in both soil and water by microbial processes.

Definition

ChEBI: Dalapon is a carboxylic acid and an organohalogen compound.

General Description

A colorless liquid. Soluble in water. Density 11.6 lb /gal. Corrosive to metals and tissue. Used as a herbicide.

Air & Water Reactions

Soluble in water. Reacts slowly in water to form hydrochloric and pyruvic acids.

Health Hazard

VAPOR: Irritating to eyes, nose and throat. LIQUID: Will burn skin and eyes. Harmful if swallowed.

Fire Hazard

Combustible. Irritating fumes of hydrochloric acid may form in fire. Volatilizes with steam.

Safety Profile

A corrosive with low toxicity by skin contact. A skin irritant. Mutation data reported. When heated to decomposition it emits toxic fumes of Cl-

Potential Exposure

AgriculturalChemical; Mutagen. Those involved in the manufacture,formulation, and application of the herbicide. Used againstquack grass, bermuda grass, johnson grass, cattails, rushes,etc.

First aid

If this chemical gets into the eyes, remove anycontact lenses at once and irrigate immediately for at least15 min, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts theskin, remove contaminated clothing and wash immediatelywith soap and water. Seek medical attention immediately. Ifthis chemical has been inhaled, remove from exposure,begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR ifheart action has stopped. Transfer promptly to a medicalfacility. When this chemical has been swallowed, get medical attention. If victim is conscious, administer water ormilk. Do not induce vomiting.

Environmental Fate

The mechanism of action of dalapon is the same as for most acids. The acid denatures tissue proteins upon contact. At lower concentrations, the dalapon causes nonlethal yellowing of sensitive plants, which clearly distinguished them from resistant plants. The mode of action of chlorinated aliphatic acids is not known but they probably affect many enzyme pathways. Dalapon is readily absorbed into roots and leaves of plants and then translocated. Lower concentrations will inhibit plant growth and cause leaf chlorosis, followed by necrosis and death. Higher concentrations of dalapon will result in significant necrosis of areas of the plant in contact with dalapon. Although the direct mechanism of these effects has remained elusive, it is thought that dalapon may affect lipid, carbohydrate, and nitrogen metabolism as secondary effects. One prevailing hypothesis for the primary dalapon affect is that dalapon exerts direct effects on plant structural proteins leading to these secondary metabolic outcomes.

storage

Color Code—White: Corrosive or Contact Hazard;Store separately in a corrosion-resistant location. Prior toworking with this chemical you should be trained on itsproper handling and storage. Store in tightly closed containers in a cool, well-ventilated area away from metals andmoisture.

Shipping

Acids, liquid, n.o.s. must carry a “CORROSIVE”label. They fall in DOT Hazard Class 8 and Packing GroupII.

Toxicity evaluation

Dalapon is somewhat persistent in soil but does not readily adsorb to soil particles. It can remain active in soil for several months when applied at high rates. In general, dalapon is considered to have low to moderate persistence with detection in soil for 2–8 weeks. Due to its inability to bind to soil particles, dalapon has a relatively high mobility in soil, with leaching possible. Microorganisms in the soil are very efficient at degrading dalapon. The herbicide is usually not found below the first 6 inches of soil layer. Breakdown is relatively rapid and complete, leading to the production of compounds that are not naturally occurring. Soil microorganisms are efficient at degrading dalapon, however, such that dalapon is not typically found in groundwater. High temperatures and increased moisture accelerate dalapon degradation in soil. Dalapon can also be degraded by ultraviolet light. In aquatic environments, dalapon is degraded by microorganisms (most important), hydrolysis, and photolysis. In the absence of microbial degradation, the half-life of dalapon is several months or longer if the water temperature is below 25°C, with the primary hydrolysis product being pyruvate. Dalapon is absorbed by both plant roots and leaves followed by translocation. With high applications, dalapon precipitates and leads to local corrosive effects on plants. Due to the ability of dalapon to be rapidly metabolized and degraded by microorganisms, hydrolyzed to pyruvate, rapidly translocated to plants, and quickly moved through the environment, it is not expected that dalapon will constitute any bioaccumulation hazard.

Incompatibilities

Metals: Highly corrosive to aluminumand copper alloys. Reacts slowly in water to form hydrochloric and pyruvic acids.