Pesticide Toxicity Profile: Substituted Benzene Pesticides
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Pesticide Toxicity Profile: Substituted Benzene Pesticides

   

Pesticide Toxicity Profile: Substituted Benzene Pesticides1

Frederick M. Fishel2

This document provides a general overview of human toxicity, provides a listing of laboratory animal and wildlife toxicities and 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, 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 infant mortality occurred who were being nursed by exposed mothers. 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 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 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 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 that these products are registered and sold by 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 (kills upon contact as well as residues); 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


 Terraneb®, Teremec®


 1,4-dichloro-2,5-dimethoxybenzene
Chlorothalonil


 Bravo®, Concorde®, Daconil®


Tetrachloroisophthalonitrile
Dicloran


 Botran®


 2,6-dichloro-4-nitroaniline
Pentachloronitrobenzene


 Terraclor®


 pentachloronitrobenzene
*Does not include manufacturers prepackaged mixtures.

Footnotes

1. This document is PI-61, one of a series of the Pesticide Information Office, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date September 1, 2005. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2. Frederick M. Fishel, Associate Professor, Agronomy Department, and Director, Pesticide Information Office; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, 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 extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Larry Arrington, Dean.


Copyright Information

This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.