EA-3990 lethality in humans is unknown but estimates have been made. Carbamates like EA-3990 are well absorbed by the lungs, gastrointestinal tracts, and the skin. Signs and symptoms from exposure to such carbamates are similar to other nerve agents. In general their penetration through the blood-brain barrier is difficult due to quaternary nitrogens in these molecules. Despite of this, EA-3990 is claimed to be about three times more toxic than VX. For VX, the median lethal dose for 70 kg men via exposure to the skin is estimated to be 10 mg, and the lethal concentration time, measuring the concentration of the vapor per length of time exposed, is estimated to be 30–50 mg·min/m3. These values for EA-3990 can be estimated to be 3.3 mg and 10–16.7 mg·min/m3 by division. Intravenous LD50 for EA-3990 is 0.0063 mg/kg for mice and 0.0026 mg/kg for rabbits.
Two methods have been described for synthesizing EA-3990 along with similar nerve agents. 2-dimethylaminomethyl-3-dimethylcarbamoxypyridine precursor is prepared. It is made via Mannich reaction by using 3-pyridol, dimethylamine and formaldehyde. Resulting 2-pyridin-3-ol is then carbamoylated with dimethylcarbamoyl chloride. For a different product other secondary amines than dimethylamine can be used; such as those containing methyl, ethyl, propyl, isopropyl, butyl and benzyl groups. In the first method 2 moles of 2-dimethylaminomethyl-3-dimethylcarbamoxypyridine and app. 1 mol α,ω-dihaloalkane in acetonitrile is heated on a steam bath for 6 hours. It is then allowed to stand overnight at room temperature. The crystalline product is collected by filtration. In the second method 2 mol and 1 mol of the previous reagents used in the first method are added together, but also a catalytic amount of sodium iodide in acetonitrile is added to the solution, which is then allowed to stand for 6 days. Crystalline material is usually formed during this period and it is then collected by filtration. In both methods, after filtration, the crystalline product is triturated with acetone. If no solid separates, ethyl acetate is added to precipitate the crude product. The product is then dissolved in hot ethanol and treated with decolorizing charcoal. Ethyl acetate is added to the filtered solution to precipitate the crystalline product. E-3990 is then collected and dried. Yield is 63%. Other stable salts of EA-3990 than bromide can be made such as sulfate, nitrate, hydrogen, oxalate and perchlorate. Other α,ω-dihaloalkanes can be used to obtain similar molecules with different carbon chain lengths.
