PRINCIPLES OF TOXICOLOGY - Biology East Borneo

15.5 FUNGICIDES 359temperatures as high as (almost) 41.8 °C (107.4 °F) have been reported. Severe overexposure topentachlorophenol can cause signs and symptoms such as delirium, flushing, pyrexia, diaphoresis,tachypnea, abdominal pain, nausea, and tachycardia.Because pentachlorophenol volatilizes from treated wood and fabric, excessively treated indoorsurfaces can lead to irritation of the skin, eyes, and upper respiratory tract. Contact dermatitis has beenreported in workers exposed dermally to pentachlorophenol. Treatment of pentachlorophenol poisoningconsists mainly of decontamination of clothing and skin and/or gastrointestinal tract as well assupportive treatment for symptoms associated with the exposure (e.g., temperature control).Pentachlorophenol can be assayed for in blood, urine, and adipose tissue. The ACGIH biologicalexposure index for pentachlorophenol is 2 mg/g creatinine total pentachlorophenol in urine prior tothe last shift of the workweek or 5 mg/L free pentachlorophenol in plasma at the end of the workshift.Dithiocarbamates/ThiocarbamatesThe dithiocarbamates and the thiocarbamates are used as fungicidal compounds and have littleinsecticidal toxicity, unlike the N-methyl carbamates (e.g., the acetylcholinesterase-inhibiting carbamate,carbaryl) discussed earlier. Examples of thiocarbamate fungicides include thiram (AAtack),metam-sodium (Vapam), ziram (Ziram 76), ferbam, and the ethylene bis dithiocarbamate (EBDC)compounds—maneb, zineb, and mancozeb.In general, the thiocarbamate class of fungicides has low acute toxicity. Thiram dust has beenreported to cause eye, skin, and mucous membrane irritation, with contact dermatitis and sensitizationreportedly occurring in a few workers. Systemic intoxications that have been associated with exposureto thiram have resulted in symptomatology similar to that cause by reactions to disulfiram (Antabuse),a dithiocarbamate medication used to treat alcoholism. Thiram, like disulfiram, is not a cholinesteraseinhibitor, but does cause inhibition of the enzyme acetaldehyde dehydrogenase (responsible for theconversion of acetaldehyde to acetic acid), and reportedly, in rare cases, workers who have beenexposed to thiram have complained of “Antabuse” reactions after ingestion of alcoholic beverages.Exposure to ziram, ferbam, and the EBDC compounds have been associated with skin, eye, andrespiratory tract irritation in humans. Maneb and zineb have been associated with cases of chronicdermatological disease, possibly due to dermal sensitization to these compounds in workers.ChlorothalonilChlorothalonil (Bravo, Daconil) (2,4,5,6-tetrachloro-1,3-benzenedicarbonitrile) has been reported tocause dermal and mucous membrane irritant effects in humans exposed to this compound. Chlorothalonilappears to have low potential for toxicity in humans.ClClClOHClClFigure 15.7 Pentachlorophenol.