Allergic chlorothalonil

Toxicology. Chlorothalonil is an irritant to the skin and eyes and has been reported to produce allergic contact dermatitis in exposed workers. 

Tetrachloroisophthalonitrile (chlorothalonil), a fungicide for agricultural and horticultural purposes, can also be used for other purposes. It is a skin irritant and a sensitizer. It has caused various skin affections, including contact dermatitis to workers in the production of the fungicide. Allergic dermatitis has been reported from exposure to the chemical used as a wood preservative (Bach and Pederson 1980 Spindeldreir et al. 1980 Johnsson et al. 1983) and as a pesticide in paints (Meding 1986 Liden 1990). 

Forturf, Termil, and Chlorothalonil, it was developed to replace the more toxic pentachlorophenol, and is itself a benzene derivative (Fig. 2). Among 20 workers in one wooden-ware factory, 7 of the 14 workers who had reactions to TCPN were shown to be allergic by positive patch testing (Johnsson et al. 1983). Symptoms in exposed workers included contact dermatitis, xerosis, thinning of skin particularly on the upper eyelid, and yellow discoloration of hands and feet. TCPN has been shown to elicit positive reactions in those allergic at patch-test concentrations of 0.01% in acetone, and at 1% produced reactions in both of two non-allergic control subjects in a 1980 case report (Bach and Pedersen 1980). 

Chlorothalonil is a pesticide fungicide commonly used in the cultivation of ornamental plants and flowers, rice, and onions. In banana plantations it is used in fumigations by airplanes. It can be used as a preservative of paints and of woods. Chlorothalonil can induce contact urticaria, irritant and allergic contact dermatitis, erythema dychromicum perstans or folliculitis mainly in agricultural workers, in those in wood-related professions or in horticulturists. 

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