Fungicides, metabolic degradation

ETU is a trace contaminant and metabolic degradation product of a widely used class of ethylene bisdithiocarbamate fungicides such as Maneb and Zineb. Half-life in H20 is 7-13 days. Octanol/water partition coefficient as log Pow -0.66 (calculated). 

Figure 4. Metabolic Degradation of the Fungicides Under Test Over 48 H...

Sato K, Tanaka H. 1987. Degradation and metabolism of a fungicide, 2,4,5,6-tetra-chloroisophthalonitrile (TPN) in soil. Biol Fertil Soils 3 205-209. 

Polychlorinated diphenyl ethers (PCDE) are common impurities in chlorophenol formulations, which were earlier used as fungicides, slimicides, and as wood preservatives. PCDEs are structurally and by physical properties similar to polychlorinated biphenyls (PCB). They have low water solubility and are lipophilic. PCDEs are quite resistant to degradation and are persistent in the environment. In the aquatic environment, PCDEs bioaccumulate. These compounds are found in sediment, mussel, fish, bird, and seal. PCDEs show biomagnification potential, since levels of PCDEs increase in species at higher trophic levels. PCDEs are also detected in human tissue. Despite the persistence and bio accumulation, the significance of PCDEs as environmental contaminants is uncertain. The acute toxicity and Ah-receptor-me-diated (aryl hydrocarbon) activity of PCDEs is low compared to those of polychlorinated di-benzo-p-dioxins (PCDD) and dibenzofurans (PCDF). Due to structural similarity to thyroid hormone, PCDEs could bind to thyroid hormone receptor and alter thyroid function. Furthermore, PCDEs might be metabolized to toxic metabolites. In the environment, it is possible that photolysis converts PCDEs to toxic PCDDs and PCDFs. 

Aniline is released in the presence of denitrifying and methanogenic microbial activity238b. The pKa value suggests that in moist soils, aniline will be protonated, and bound to soil, which inhibits degradation. Volatilization does not take place from dry soils, based on the vapor pressure. Studies have been made on the metabolism of aniline-derived products, such as herbicides and fungicides, in soil. Chloroanilines bind to organics in... 

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