Herbicide contamination

Significant levels of herbicides have also been detected in rivers, although these are usually transitory. Heavy rainfall can move herbicides from agricultural land to nearby ditches and streams due to runoff, and in soils that are high in clay, percolation of water occurs through deep fissures with consequent movement into neighboring water courses. Such events under extreme weather conditions are likely to have contributed to the pulses of herbicide contamination observed in some rivers. Questions have been asked about possible effects of such episodic pollution on populations of aquatic plants. 

In the book The Safe Use of Pesticides While Intensifying Agricultural Production [21], the paragraphs on polychlorpinen in beet fields were lost among data linked to OCP contamination of breast milk in Japan, the USA, and Sweden the dangers to the inhabitants of Italy from herbicide contamination of the Po river the poisoning of the inhabitants of the USA and Canada by watermelon from a plantation treated with pesticides and many other facts. Here is the text on the beet fields ... 

Readman JW, Albanis TA, Barcelo D, Galassi S, Tronczynski J, Gabrielides GP (1993) Herbicide contamination of Mediterranean estuarine waters - results from a Med Pol Pilot Survey. MarPollut Bull 26(11) 613—619... 

Synonyms AIDS-105033 BRN 0271116 C-07557 CCRIS 576 Dioxin Dioxin (herbicide contaminant) Dioxine EINECS 217-122-7 NCI-C03714 TCDBD 2,3,7,8-TCDD 2,3,7,8-Tetra-chlorodibenzodioxin 2,3,7,8-Tetrachlorodibenzo[7>,e][l,4]dioxin 2,3,7,8-Tetrachlorodibenzo-1,4-dioxin 2,3,7,8-Tetrachlorodibenzo-p-dioxin Tetradioxin. 

Dioxin (herbicide contaminant), see TCDD Dioxine, see TCDD p-Dioxobenzene, see Hydroquinone... 

Tables 12.2 and 12.3. The effect of vertical variability is shown in Table 12.2, while the lateral spatial variability is shown in Table 12.3. The vertical and lateral spatial variabilities were defined on the basis of either the measured adsorption coefficient K), as generated from adsorption isotherms on soil profiles, or on adsorption coefficients on soil organic matter calculated as adsorption on organic carbon per unit weight of soil. We see that both vertical (Table 12.2) and lateral (Table 12.3) variability of soil affect the adsorption coefficients. A comparison between the bromide (conservative) and the two nonconservative herbicides distributions with depth after about 900mm of leaching is shown in Fig. 12.3. We see that, in the case of bromide, there is a continuous displacement of the center of mass with cumulative infiltration. In contrast, the bulk of the herbicide contaminant mass remains in the upper soil layer, with very little displacement.

Gonzalez-Gonzalez, L.R. Buenrostro-Zagal, J.F. Luna-Martinez, A.D. Sandoval-Gomez, Y.G. Schettino-Bermudez, B.S. Treatment of an herbicide-contaminated wastewater in a membrane bioreactor by sulfate-reducing consortia. Proceedings, 7th International Symposium on In Situ and On-Site Bioremediation, Orlando, Florida, June 2-5, 2003. 

Davies, P.E., L.S.J. Cook, and J.L. Barton (1994). Triazine herbicide contamination of Tasmanian streams Sources, concentrations, and effects on biota. Aust. J. Marine and Freshwater Res., 45 209-226. 

Gruessner, B. and M.C. Watzin (1995). Patterns of herbicide contamination in selected Vermont streams detected by enzyme immunoassay and gas chromatography/mass spectrometry. Environ. Sci.Technol., 29 2806-2813. 

An herbicide contaminating a lake was measured on several consecutive days. Its concentration was found to decrease linearly with time and was at a level of 24 mg/L when first measured and 10 mg/L on the 5th day after measurement was initiated. Predict when the level would reach a value deemed safe by regulations governing this pollutant in water of 0.5 mg/L. Suggest some cautions that should be observed in relying on such a calculation. 

Young AL, Kang HK, Shepard BM. 1983. Chlorinated dioxins as herbicide contaminants. Environ Sci Technol 17 530A-540A. 

SYNS 2,3,7,8-czTEROCHLORODVc UBENZo-p-DWUOKSYNY (POLISH) DIOKSYNY (POLISH) DIOXIN (herbicide contaminant) DIOXINE NCI-C03714 TCDBD 2,3,7,8-TCDD 2,3,6,7-TETRACHLORODI-BENZO-p-DIOXIN 2,3,7,8-TETRACHLORODlBENZO-(b,e)(l,4)DIOXAN 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN 2,3,7,8-TETRACHLORODIBENZO-l,4-DIOXIN TETRADIOXIN... 

DIOXIN (herbicide contaminant) see TAIOOO DIOXINE see TAIOOO DIOXITOL see CBROOO... 

TCDD Manufacture of chlorophenols, herbicide contaminant, incineration of chemical wastes... 

A disadvantage of a weed wiper is that when a treatment is complete there can be a large area of the wiper still contaminated with herbicide. This has to be hosed off with water, using a brush to ensure penetration of the absorbent surface. It is important to ensure that the herbicide contaminated washings can be disposed of safely and, when dry, the wiper should be covered by a protective sleeve. 

Table IV. Aquifer Characteristics and Herbicide Contamination of Groundwater in Floyd and Mitchell Counties, Iowa (after 60)...

Most of what is known about the toxicity of dioxins in the human comes from individuals exposed incidentally or chronically to higher levels (e.g., industrial accidents or presence in areas sprayed with Agent Orange or other herbicides contaminated with dioxins.). The lowest dose effects are probably associated with thymic atrophy and decreased immune response, chloracne and related skin lesions, and neoplasia (cancer). Dioxins can cross into the placenta to cause developmental and reproductive effects, decreased prenatal growth, and prenatal mortality. 

The conclusion draum from pesticide monitoring studies carried out in various areas of the United States is that non-purposeful herbicide contamination of natural waters occurs infrequently and at low levels. Residues in water from purposeful use of herbicides for control of weeds in aquatic sites are relatively high initially however, the levels are reduced rapidly, and residues are often not detectable after a few days or weeks. Herbicide residue levels found in aquatic organisms commonly reflect the concentrations of herbicides present. With few exceptions aquatic herbicides do not accumulate and persist in fish or shellfish. Most aquatic organisms cleanse themselves of herbicide residues soon after these disappear from the water. Herbicide use, while controversial, continues until more effective and acceptable control measures evolve. 

Vighi, M. and Zanin, G. (1994). Agronomic and ecotoxicological aspects of herbicide contamination of groundwater in Italy. In ed. L. Bergman and M. Pugh Environmental Toxicology, Economics and Institutions - The Atrazine Case Study, pp. 111-25. Kluwer Academic Publishers, Dordrecht. 

Zanin, G., Borin, M., Altissimo, L. and Calamari, D. (1993). Simulation of herbicide contamination of the aquifer north of Vicenza (north-east Italy). Chemosphere, 26,929 0. 

Microwave-assisted extraction coupled with gas chromatography-electron capture negative chemical ionization mass spectrometry (MAE-GC-EC-NCI-MS) was described for the simphfied determination of imidazohnone herbicide-contaminated soils at the ppb level [275]. 

HUMANS EXPOSED TO MATERIALS REPORTED TO BE CONTAMINATED WITH TCDD HAVE DEVELOPED CHLORACNE AND OTHER SIGNS OF SYSTEMIC POISONING. SOFT TISSUE SARCOMA HAS BEEN OBSERVED IN EXCESS AMONG WORKERS EXPOSED TO PHENOXY HERBICIDES. THESE DATA ARE INCONCLUSIVE REGARDING TCDD TOXICITY IN HUMANS BECAUSE THE POPULATIONS STUDIED HAD MIXED EXPOSURES MAKING CAUSAL RELATIONSHIPS BETWEEN EXPOSURE AND EFFECT UNCLEAR. THE DATA ARE, HOWEVER, SUGGESTIVE OF AN ASSOCIATION BETWEEN EXPOSURE TO PHENOXYACETIC HERBICIDES CONTAMINATED WITH TCDD AND EXCESS LYMPHOMA AND STOMACH CANCER. ATTEMPTS TO ASSOCIATE REPRODUCTIVE EFFECTS WITH TCDD EXPOSURE ARE INCONCLUSIVE BECAUSE OF THE INADEQUATELY DEFINED POPULATIONS STUDIED AND THE DIFFICULTIES OF DEFINING EXPOSURE. 

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