Binding of DDT

Figures 1 and 2 show the effect of temperature on the extent of binding of DDT to both Pakim Pond Humic Acid and Boonton Humic Acid. The Y axis in these figures is the amount of DDT bound to the humic acid in nanograms of DDT per gram of humic acid. The X axis is the free, truly dissolved DDT in nanograms per liter. This is similar to the presentation of an adsorption isotherm. If the slope of the lines is multiplied by 1000 it becomes analogous to a weight-weight partition coefficient ([g DDT/g D0C]/[g DDT/g water]). This will be referred to as the binding constant.

Figure 3 presents some measurements of the extent of binding of DDT to dissolved organic carbon in secondary sewage effluent. The data is somewhat noisy, partially due to the fact that a portion of the DOC was able to pass through the dialysis bag. Nonetheless, the experiments showed that the DDT was bound to the sewage effluent DOC. 

Carter, C. W. Suffer, I. H. (1982). Binding of DDT to dissolved humic materials. Environmental Science Technology, 16, 735—40. 

Samuel, T., Agrawal, H.C., Pillai, M.K.K., 1983. Persistence and binding of DDT and gamma-HCH in a sandy loam soil under field conditions in Delhi, India. Pestic. Sci. 22, 1-15. 

Spies, R. and P. Thomas. Reproductive and endocrine status of female kelp bass from a contaminated site in the Southern California Bight and estrogen receptor binding of DDTs. In Chemically Induced Alterations in Functional Development and Reproduction of Fishes, edited by R.R. Rolland, M. Gilbertson and R.E. Peterson, Pensacola, SETAC Press, pp. 113-134, 1997. 

The binding constants of a number of compounds were measured using dialysis, solubility and sorption techniques. The solubility technique was used for compounds which were not radiolabeled. All data was collected at pH = 8.3. The binding constants were then compared to the octanol/water partition coefficients for the compounds and the molar solubilities of the compounds. The data is presented in Table II. The Kow values were taken from the literature.18 22-2 The solubility values were determined in this research with the exception of DDT and Lindane, which were taken from the literature. A plot of log Kc vs. log Kow is presented in Figure 5. The slope of this line is 0.71, the intercept is 0.75 and the value of the correlation coefficient is 0.9258. The regression is highly significant... 

Unfortunately there is also some bad news for modelers. Different humic materials bind compounds to dramatically different extents, and the reasons for this are unclear. Figure 6 shows the binding constants of DDT to seven different humic materials. Some of this data is from a factorial experiment which has been published elsewhere.7 Inspection of this data shows that the humic acids and the... 

Mitotane, or o,p -DDD, is an oral medication used in the treatment of adrenocortical carcinoma. Chemically it is an isomere of DDT. Following its metabolism in the adrenal cortex to a reactive acyl chloride intermediate, mitotane covalently binds to adrenal proteins, specitically inhibiting adrenal cortical hormone production. The drug accumulates in fat tissue. It is eliminated mainly by the kidneys with a half-life of 18-159 days. Common side effects include anorexia, nausea, lethargy, sleepiness and skin problems. 

McBlain, W.A., The levo enantiomer of o,p -DDT inhibits the binding of 17j8-estradiol to the estrogen receptor Life Sci. 1987, 40, 215-221. 

The effect of proteins on pollutant toxicity includes both quantitative and qualitative aspects. Experiments show that animals fed proteins of low biological value exhibited a lowered microsomal oxidase activity when dietary proteins were supplemented with tryptophan, the enzyme activity was enhanced. Alteration of xenobiotic metabolism by protein deprivation may lead to enhanced or decreased toxicity, depending on whether metabolites are more or less toxic than the parent compound. For example, rats fed a protein-deficient diet show decreased metabolism but increased mortality with respect to pentobarbital, parathion, malathion, DDT, and toxaphene (Table 6.4). On the other hand, rats treated under the same conditions may show a decreased mortality with respect to heptachlor, CC14, and aflatoxin. It is known that, in the liver, heptachlor is metabolized to epoxide, which is more toxic than heptachlor itself, while CC14 is metabolized to CC13, a highly reactive free radical. As for aflatoxin, the decreased mortality is due to reduced binding of its metabolites to DNA. 

---