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Publication #PI-61

Pesticide Toxicity Profile: Substituted Benzene Pesticides1

Frederick M. Fishel2

This document provides a general overview of human toxicity and a listing of laboratory animal and wildlife toxicities as well as a cross reference of the chemical, common, and trade names of the substituted benzene pesticides registered for use in Florida.

General

The substituted benzene pesticides are a group of fungicides with a wide range of uses. Applications are made as treatments to seed, soil, and the foliage of vegetables and field crops, flowers, bulbs, and turfgrass. Some of the members of this pesticide family, such as pentachloronitrobenzene (PCNB), have been in use since the 1930s. PCNB is used to treat seed and soil at planting, and for selected foliage applications. The widely used fungicide, chlorothalonil, first became available in 1964 and has proven to be very useful in applications as a broad-spectrum foliage-protectant fungicide. Another member of this group, chloroneb, is used for treatment of seed and turf, while dicloran is registered for use in Florida as a broad-spectrum fungicide used to protect perishable produce. One member of this group, hexachlorobenzene, has been discontinued for use in the United States. It was shown to cause adverse health effects to Turkish farm dwellers in the 1950s, and some infants who were being nursed by exposed mothers died. Product formulations of the substituted benzenes include wettable powders, dusts, water-dispersible granules, emulsifiable concentrates, and granules.

Toxicity

Chloroneb has very low oral toxicity in mammals. It may be moderately irritating to the skin and the mucous membranes. A metabolite of chloroneb, dichloromethoxyphenol, is excreted in the urine. No cases of systemic human poisoning have been reported. Chlorothalonil has caused irritation of the skin, the mucous membranes of the eyes, and the respiratory tract upon contact. Allergic dermatitis has been reported, but no cases of systemic poisoning in humans have been recorded. Apparently, chlorothalonil is poorly absorbed across the skin and the gastrointestinal lining. Dicloran is absorbed by exposed workers, but is promptly eliminated, at least partly in the urine. No long-term adverse effects have been observed in humans. High concentrations of pentachloronitrobenzene in prolonged skin contact have caused sensitization in some tested volunteers, but high concentrations have not been reported from occupationally exposed workers. Systemic poisonings have not been reported. Mammalian toxicities for the substituted benzene pesticides are shown in Table 1. Table 2 lists the toxicities to wildlife by the common name of the pesticide. Table 3 provides a cross listing of many of the trade names under which these products are registered and sold in Florida.

Additional Information

Tables

Table 1. 

Substituted benzene pesticide mammalian toxicities (mg/kg of body weight).

Common name

Rat oral LD50

Rabbit dermal LD50

Chloroneb

>5,000

>5,000

Chlorothalonil

>10,000

>10,000

Dicloran

>5,000

>2,000

Pentachloronitrobenzene

>5,000

>5,000 (rat)

Table 2. 

Substituted benzene pesticide wildlife toxicity ranges.

Common name

Bird acute oral LD50 (mg/kg)*

Fish (ppm)**

Bee

Chloroneb

PNT

MT

---

Chlorothalonil

PNT

ST

PNT

Dicloran

ST

MT

PNT

Pentachloronitrobenzene

PNT

HT

PNT

*Bird LD50: Practically nontoxic (PNT) = >2,000; slightly toxic (ST) = 501 – 2,000; moderately toxic (MT) = 51 – 500; highly toxic (HT) = 10 – 50; very highly toxic (VHT) = <10.

**Fish LC50: PNT = >100; ST = 10 – 100; MT = 1 – 10; HT = 0.1 – 1; VHT = <0.1.

†Bee: HT = highly toxic (applied product and residues kill on contact); MT = moderately toxic (kills if applied over bees); PNT = relatively nontoxic (relatively few precautions necessary).

Table 3. 

Cross reference list of common, trade and chemical names of substituted benzene pesticides.

Common name

Trade names*

Chemical name

Chloroneb

Teremec®

1,4-dichloro-2,5-dimethoxybenzene

Chlorothalonil

Aftershock, Allpro, Antiblu, Armor Tech Bravo®, Busan, Chloro Gold, Chlorothalonil, Cleanwood Micro, Clortram, Consyst, CTN SPC 720, Daconil®, Densil, Docket, Echo, Ensign, Equus, Fungonil, Initiate, Legend, Mainsail, Manicure, Mold-ram, Ortho, Phoenix, Rocima, SA-50, Spectro, Thalonil, Thor

Tetrachloroisophthalonitrile

Dicloran

Botran®

2,6-dichloro-4-nitroaniline

Pentachloronitrobenzene

Blocker,Terraclor®, Turfcide

pentachloronitrobenzene

*Does not include manufacturer's prepackaged mixtures.

Footnotes

1.

This document is PI-61, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date September 2005. Revised March 2014. Reviewed March 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

Frederick M. Fishel, professor, Agronomy Department, and director, Pesticide Information Office; UF/IFAS Extension, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. All chemicals should be used in accordance with directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.