Organic mercurial fungicides

Figure 9. Structures of some organic mercurial fungicides Herbicides...

Gotelli CA, Astolfi E, Cox C, et al. 1985. Early biochemical effects of an organic mercury fungicide on infants "Dose makes the poison." Science 277 638-640. 

Mercury. The fkst successful use of mercury as a fungicide occurred in 1913 (8). The fkst seed treatment compound developed was chloro(2-hydroxyphenyl)mercury [90-03-9] (1). Subsequentiy, a number of organic mercury derivatives having general formula RHgX have been used. 

Heavy metals may also be concentrated in passage up the food chain. Other pollutants, e.g. fungicides, pesticides, biocides, polychlorinated biphenyls or organic mercury compounds, are persistent and can therefore also bioaccumulate. 

A number of chlorinated phenols are also important as fungicides. These include pentachlorophenol, tetrachlorophenol, and trichlorophenol. In addition, organic mercurials have been in use for years. A few compounds of this class are shown in Figure 9. Some of these compounds are water-soluble and are used as slimicides in paper mills most are insoluble and are used to control soil-borne diseases. Some also have comparatively... 

All organic and inorganic mercurial fungicides have lost their registrations and are no longer available for any purposes. 

Fuberidazol is used to combat snow mold, and mainly in combination with other substances for cereal seed stock disinfection. It was one of the first organic fungicides able to replace organic mercury as a seed protectant. 

Organic Mercury. Associations were reported between the use of mercury-containing fungicides (i.e., mercury levels in hair) and leukemia in farmers and between the use of mercury-containing seed... 

Organic Mercury. Organic mercury compounds are more readily absorbed by the oral route than inorganic mercury compounds. Based on retention and excretion studies in humans, approximately 95% of an oral tracer dose of aqueous methylmercuric nitrate was absorbed (Aberg et al. 1969). Absorption of mercury was also reported in studies in which volunteers received doses of methylmercury bound to protein (Miettinen 1973) or ate bread contaminated with a fungicide that contained methylmercury (Al-Shahristani et al. 1976) however, no quantitative data regarding the percentage of absorption were available. 

Use Fungicide for seed or bulb treatment, either alone or with other organic mercury compounds. See mercury. 

Use Manufacture of phenylmercuric salts, fungicide, and germicide. Principal compound in manufacturing organic mercury derivatives, denaturant for alcohol. 

Mercury used to get into the environment in large amounts from the production of chlorine, from slimicides and fungicides used in the paper industry, and from fumigants. Mercury is one of the electrodes for the electrolysis of salt water to produce chlorine and sodium hydroxide. The contaminated mercury used to be dumped into lakes and rivers (0.45 Ib/ton of CE produced) because it was believed to be so heavy that it would just settle to the bottom. However, it was found that certain microorganisms could convert the mercury to organic mercury compounds, almost exclusively methyl mercury, which can be quite toxic. 

Organic mercury compounds containing an alkyl group with a low carbon atom number are classed in this group. The fungicidal effect of the derivatives decreases with increasing carbon atom number (Gassner, 1951), so that, in practice, only methyl- and ethylmercury compounds are important. 

Owing to the environmental dangers of mercury, its use in pesticides has been limited. In Japan, organic mercury compounds used in fungicides in rice culture were replaced by phosphoric acid esters in 1968. However, the quantity of mercury used in agriculture is responsible for only a small part of the mercury polluting the environment, and the overall problem of environmental pollution by mercury is not yet solved. 

Nuodex. [Servo] Organic mercury compd. fungicide, bactericide for paints preservative for aq. systems. 

In addition, some occupational exposure to organic mercury compounds may occur in some countries, where alkyl- (mainly methyl-) and alkoxy- (mainly methoxyethyl-) mercury salts are used as seed dressings (Skerfving and Copplestone, 1976), and phenylmercury is sometimes used as a fungicide. 

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