Common name: Dicofol

Chemical abstracts name:     2,2,2-trichloro-1,1-bis(4-chlorophenyl)ethanol

Type: Acaricides

CAS RN: 115-32-2

M.F.: C₁₄H₉Cl₅O

Mol Wt: 370.51

 

Form (appearance): Pure dicofol is a white crystalline solid. Technical dicofol is a red-brown or amber viscous liquid with an odor like fresh-cut hay

M.P.: 78.5-79.5 C for pure dicofol [1,5]; 50 C for technical dicofo

Boiling point:  225

V.P.: Negligible at room tempera

S.G.: 1.45

Solubility.: 0.8 mg/L @ 25 C, solute in most organic solvent

Stability: Stable to acids but not to alkaline media. Slightly corrosive to metals.

Partition Coefficient: 4.2788

Adsorption Coefficient: 5000 (estimated)

 

Formulation types: EC ; WP.

Biochemistry: Dicofol showed a similar pattern of distribution on elimination as DDT but it is more polar and therefore less persistent in the body. In adipose tissue the parent compound was predominant

Mode of action: Produces stimulation of axonal transmission of nervous signals, believed to be related to inhibition of ATPases in the central nervous system (CNS). The signs of toxicity are consistent with CNS depression.

Uses: Dicofol is an organochlorine miticide used on a wide variety of fruit, vegetable, ornamental and field crops. Dicofol is manufactured from DDT. In 1986, use of dicofol was temporarily canceled by the EPA because of concerns raised by high levels of DDT contamination. However, it was reinstated when it was shown that modern manufacturing processes can produce technical grade dicofol which contains less than 0.1% DDT.

 

Oral: Acute oral LD₅₀ for male rats 595, female rats 597, male mice 669, female mice 675 mg/kg b.w.

Skin and eye: Acute percutaneous LD₅₀ for rats 1810 mg/kg b.w. dermal LD50 in rats is 1000 to 5000 mg/kg, and in rabbits is between 2000 and 5000 mg/kg,

Inhalation: LC₅₀ (4 h) for rats 5 mg/l air.

Noel: (2 y) for rats 2.5mg/kg diet; (1 y) for dogs 25 mg/kg diet. Non-oncogenic in 2 y studies in rats and mice.

ADI: 0.02 mg/kg b.w.

 

Birds: Acute oral LD₅₀ for mallard ducks 1651 mg/kg. Dietary LC₅₀ 2126 ppm.

Fish: LC₅₀ (96 h) for bluegill sunfish 0.51, carp 14, rainbow trout 0.12 mg/l.

LD₅₀ (contact) > 50 μg technical grade per bee

LD₅₀ (oral) > 10 μg technical grade per bee

Daphnia EC₅₀ (48 h): 0.14 mg/litres

 

Breakdown in soil and groundwater: Dicofol is moderately persistent in soil, with a half-life of 60 days. Dicofol is susceptible to chemical breakdown in moist soils. It is also subject to degradation by UV light. In a silty loam soil, its photodegradation half-life was 30 days. Under anaerobic soil conditions, the half-life for dicofol was 15.9 days. Dicofol is practically insoluble in water and adsorbs very strongly to soil particles. It is therefore nearly immobile in soils and unlikely to infiltrate groundwater. Even in sandy soil, dicofol was not detected below the top 3 inches in standard soil column tests. It is possible for dicofol to enter surface waters when soil erosion occurs.

Breakdown in water: Dicofol degrades in water or when exposed to UV light at pH levels above 7. Its half-life in solution at pH 5 is 47 to 85 days. Because of its very high absorption coefficient (Koc), dicofol is expected to adsorb to sediment when released into open waters.

Breakdown in vegetation: In a number of studies, dicofol residues on treated plant tissues have been shown to remain unchanged for up to 2 years.