Dithiocarbamate fungicides

T. Noguer, A. Gradinaru, A. Cincu, and J.L. Marty, A new disposable biosensor for the accurate and sensitive detection of ethylenebis(dithiocarbamate) fungicides. Anal. Lett. 32, 1723—1738 (1999). 

T. Noguer, B. Leca, G. Jeanty, and J.L. Marty, Biosensors based on enzyme inhibition detection of organophosphorus and carbamate insecticides and dithiocarbamate fungicides. Field Anal. Chem. Tech. 3, 171-178 (1999). 

Another well-known example within the pesticide area is the group ADI of 0-0.03 mg/kg bw/day allocated to dithiocarbamate fungicides. Thus, the Joint FAO/WHO Meeting on Pesticide Residues (JMPR) in 1993, in its evaluation of mancozeb, concluded that... 

This response is absolute nonsense. Sweden had banned the herbicide amitrole and several bis-dithiocarbamate fungicides because of flawed scientific evaluations that misinterpreted thyroid tumors in rodents, known to lack relevance for humans, as indicators of a human risk associated with normal usage. In contrast to Sweden s action, IARC and the U.S. Environmental Protection Agency cleared all of them of suspicions of causing cancer at current exposure levels,45 and the EU has approved amitrole for general use. Sweden s Minister of the Environment, Kj ell Lars-son, has declared that Sweden will fight all the way to the European Court of Justice to stop reintroduction of these horribly dangerous pesticides. 

Carbamates are substituted esters of carbamic acid (NH2COOH) with aliphatic or aromatic substituents on the oxygen and nitrogen atoms. Carbamate insecticides have an aryl or oxime N-methylcarbamate structure, and their mode of action is based on the inhibition of the enzyme acethylcholine esterase (1). However, this inhibition is reversible, and recovery from sublethal doses occurs rapidly. Some carbamate fungicides have a dithio, bisdithio, or benzimidazole carbamate basic structure, and dithiocarbamate fungicides inhibit the enzyme aldehyde deshydro-genase (2). The herbicides have an /V-alkylthiocarbamate or A-phenylcarbamate structure and interfere with photosynthetic activity or affect meristematic activity or lipid metabolism (3). Representative structures of carbamate pesticides are shown in Fig. 1. 

Dithiocarbamate fungicides consist of metal salts of dimethylthiocarbamate and ethylenebis-dithiocarbamate anions, as shown in Figure 17.5. These fungicides are named in accordance with the metal ion present. For example, the manganese salt of dimethyldithiocarbamate is called maneb, and the zinc and sodium salts are zineb and nabam, respectively. The iron salt of ethylenebisdithio-carbamate is called ferbam, and the zinc salt of this ion is called ziram. These salts are chelates (Section 2.3) in which two S atoms from the ethylenebisdithiocarbamate anion are bonded to the same metal ion in a ring structure. 

The dithiocarbamate fungicides have been popular for agricultural use because of their effectiveness and relatively low toxicities to animals. However, there is concern over their environmental breakdown products, particularly ethylenethiourea (2-imidazolidine thione see Figure 17.5), which is toxic to the thyroid and has been shown to be mutagenic, carcinogenic, and teratogenic in experimental animals. 

Give the names and structures of two dithiocarbamate fungicides. How are they used How are zinc and iron involved with these fungicides ... 

From our own work I cite two examples which just may serve to illustrate the importance of metal-ligand interactions in the functioning of dithiocarbamate fungicides. 

Figure 8. Basic structures typical of the dithiocarbamate fungicides...

Nakazawa, H. et al. Determination of dithiocarbamate fungicides by reversed-phase ion-pair liquid chromatography with chemiluminescence detection. /. Liq. Chromatogr. Rel. Technol. 2004, 27, 705-713. 

Cantarelli, D., Tarufl, R, Martini A. (1964). Chemical and microbiological surveys on the effects of dithiocarbamate fungicides on wine-making. J. Sci. Food Agric., 15, 186-196. 

Pesticides Carbamate insecticides and herbicides, chlorinated pesticides (for example aldrin, dieldrin, heptachlor, DDT, DDE, HCB, HCH isomers), dithiocarbamate fungicides, organic phosphates, triazine herbicides... 

Maneb is an ethylene(bis)dithiocarbamate fungicide used in the control of early and late blights on potatoes, tomatoes and many other diseases on various fruits, vegetables, field crops, and ornamentals. Maneb has been shown to be effective on a wider spectrum of fruit, vegetable, and turf diseases caused by fungi compared to other fungicides. It is available as granular, wettable powder, flowable concentrate, and ready-to-use formulations. 

D (2,4-dichlorophenoxyacetic acid) patented as a plant growth regulator and later as a general herbicide dithiocarbamate fungicide marketed... 

Guven, K., Power, R.S., Avramides, S., Allender, R. and de Pomerai, D.I. (1999) The toxicity of dithiocarbamate fungicides to soil nematodes, assessed using a stress-inducible transgenic strain of Caenorhahditis elegans. Journal of Biochemical and Molecular Toxicology, 13, 324-333. 

Dithiocarbamate fungicides containing cbfferent metal ions such as Zn, Mn " " and Fe were resolved using a C q column that performed better than the conventional RP-C18 sorbent [123]. However, the method did not allow the speciation of dithiocarbamates that contain no metal. Finally, C q—fullerene was reported to be an effective sorbent material for preconcentrating mercury compounds, and to be preferable to RP-C18 on account of its large specific surface area and volume, which endow it with an increased physical sorption capacity [124]. Also recendy, Pereira et al. [125] developed a new alternative for Cd and Pb determinations at low concentrations, using the preconcentration of a Cjio/CyQ mixture coupled to thermospray flame furnace atomic absorption spectrometry. 

Zinc dithiocarbamate fungicides and stabilizers Treating cellulose to make vulcanized fiber Phosphors... 

Komulainen H and Savolainen K. 1985. Effect of dithiocarbamate fungicides and thiurams on H-haloperidol binding in rat brain. Arch Toxicol Suppl 8 77-79. 

Maini P and Boni R. 1986. Gas chromatographic determination of dithiocarbamate fungicides in workroom air. Bull Environ Contam Toxicol 37 931-937. 

Marty JL and Noguer T. 1993. Bi-enzyme amperometric sensor for the detection of dithiocarbamate fungicides. Analusis 21 231-233. 

Petrova-Vergieva T and Ivanova-Tchemishanska L. 1973. Assessment of the teratogenic activity of dithiocarbamate fungicides. Food Cosmet Toxicol 11 239-244. 

Woodrow JE, Seiber JN, Fitzell D. 1995. Analytical method for the dithiocarbamate fungicides ziram and mancozeb in air Preliminary field results. J Agric Food Chem 43 1524-1529. 

Dithiocarbamate fungicides attained importance in plant protection after World War II (ziram and ferbam were the first foliage fungicides prepared on a large industrial scale), and even today, in the age of systemic fungicides, their use has not decreased (Tweedy, 1973). Despite much intensive research, however, only a few dithiocarbamate derivatives have found practical application. 

Pesticides as a class contain 2 widely quoted examples of ambiguity between mutagenic activity and carcinogenicity. Dichlorvos (2,2-dichlorovinyl dimethyl phosphate), an organophosphate insecticide, and ziram (bis(dimethyldithio-carbamate)zinc), a dithiocarbamate fungicide, are confirmed bacterial mutagens [13]. 

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