Dicofol

This has caused criticism by many environmentalists; however, the World Health Organization classifies dicofol as a Level II, "moderately hazardous" pesticide.

Dicofol first appeared in the scientific literature in 1956, and was introduced onto the market by the US-based multinational company Rohm & Haas in 1957.

Other current manufacturers include Hindustan Insecticides Limited (India), Lainco (Spain), and ADAMA Agricultural Solutions (Formerly Makhteshim-Agan) (Israel).

In 1986, the US Environmental Protection Agency (EPA) temporarily canceled the use of dicofol because relatively high levels of DDT contamination were ending up in the final product.

The Pesticide Survey, USA 1987 through 1996, reports that the total annual domestic agricultural usage of dicofol averaged about 860,000 pounds active ingredient (a.i.)

The largest markets for dicofol in terms of total pounds active ingredient are cotton (over 50%) and citrus (almost 30%).

An assessment of dicofol by the UK Pesticides Safety Directorate in 1996 found that residues in apples, pears, blackcurrants and strawberries were higher than expected.

In 1980, an accident at the US Tower Chemical Company led to a release of dicofol into Lake Apopka in Florida.

Ten years later Dr Guillette of Florida University linked this incident to a subsequent decline in the fertility of alligators in the lake.

The US EPA is still not clear whether dicofol is involved in the reproductive failure of the alligator population following the accidental spill.

Intense activity or starvation may mobilize the chemical, resulting in the reappearance of toxic symptoms long after actual exposure.

Tests on laboratory animals show that the primary effects after long term exposure to dicofol include increases in liver weight and enzyme induction in the rat, mouse and dog.

In the rat hormonal changes were accompanied by the histological observation of vacuolation (empty cavities) of the cells of the adrenal cortex.

Rats fed diets containing dicofol through two generations exhibited adverse effects on the survival and/or growth of newborns at 6.25 and 12.5 mg/kg/day A 2007 study by the California Department of Public Health found that women in the first eight weeks of pregnancy who live near farm fields sprayed with dicofol and the related organochloride pesticide endosulfan are several times more likely to give birth to children with autism.

These results are highly preliminary due to the small number of women and children involved and lack of evidence from other studies.

Eggshell thinning and reduced offspring survival were noted in the mallard duck, American kestrel, ring dove, and screech owl.

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.

Skeletal formula of dicofol
Ball-and-stick model of the dicofol molecule
Space-filling model of the dicofol molecule