Hexachlorobenzene, HCB

In another AT study, Terrado et al. [15] characterised pollution patterns in different parts of the Ebro catchment. In the upper part of the Ebro, pollution was found to be mainly in the form of heavy metals (Zn, Cu, Cr, Pb, Cd and Hg), polycyclic aromatic hydrocarbons (PAHs), hexachlorocyclohexanes (HCHs) and trichlorobenzenes (TCBs). Etrophic conditions were also found. Pollution was found to source mainly from industry and urbanisation. The central Ebro was characterised by nutrient pollution such as the accumulation of Ca, Na, Mg and K, which highlighted the importance of salinisation effects from intensive irrigation and soils with high salt content. In the lower Ebro, organic [DDTs, hexachlorobenzene (HCB) and hexachlorobutadiene (HCBu)] and heavy metal (Hg, Cd, Zn and As) contamination was found to derive mainly from industrial and agricultural activities. 

Fig. 5 Main contamination sources identified by PCA for sediments, fish, and suface water in the Ebro River basin, and explained variances for each principal component. Variable identification. Organic compounds in sediments 1, summatory of hexachlorocyclohexanes (HCHs) 2, summa-tory of DDTs (DDTs) 3, hexachlorobenzene (HCB) 4, hexachlorobutadiene (HCBu) 5, summatory of trichlorobenzenes (TCBs) 6, naphthalene 7, fluoranthene 8, benzo(a)pyrene 9, benzo(b) fluoranthene 10, benzo(g,h,i)perylene 11, benzo(k)fluoranthene 12, indene(l,2,3-cd)pyrene. Organic compounds in fish 1, hexachlorobenzene (HCB) 2, summatory of hexachlorocyclohexanes (HCHs) 3, o,p-DDD 4, o,p-DDE 5, o,p-DDT 6, p,p-DDD 7, />,/>DDE 8, />,/>DDT 9, summatory of DDTs (DDTs) 10, summatory of trichlorobenzenes (TCBs) 11, hexachlorobutadiene (HCBu) 12, fish length. Physico-chemical parameters in water 1, alkalinity 2, chlorides 3, cyanides 4, total coliforms 5, conductivity at 20°C 6, biological oxygen demand 7, chemical oxygen demand 8, fluorides 9, suspended matter 10, total ammonium 11, nitrates 12, dissolved oxygen 13, phosphates 14, sulfates 15, water temperature 16, air temperature...

Prenatal exposure of mice to the fungicide hexachlorobenzene (HCB) resulted in suppression of the delayed type hypersensitivity (DTH) response to oxazolone. Similar to the DTH response, the in vitro mixed lymphocyte response (MLR) was also suppressed by in utero exposure.101... 

Of all rat strains, the Brown Norway (BN) rat is used most frequently in relation to chemical-induced autoimmunity. This strain displays clinically manifested autoimmune disease following exposure to a number of chemicals. HgCl2 is the most scrutinized compound in the BN rat but D-penicillamine [6-8], gold-salts [9,10],hexachlorobenzene (HCB) [11-14] and recently, nevirapine [15], have all been shown to induce clinical effects. Captopril [7] and felbamate [16] appeared not to induce autoimmune effects in BN rats. 

The toxic effects of the fungicide and environmental pollutant hexachlorobenzene (HCB) were first noted in the 1950s when people were exposed to high doses of HCB through intake of contaminated grain. Intoxicated individuals developed a variety of symptoms including hepatic porphyria, skin lesions, and arthritis. Symptoms were accompanied by infiltrates of inflammatory cells [11, 33],... 

When the individual insecticides are present in the solution in such a concentration range, the electron capture responds nearly uniformly to all insecticides. A column filled with 1.5% silicone OV-17 plus silicone oil (fluoralchylsiloxane) on Chromasorb W (80-100 mesh) is used for separation of the BHC alpha, beta, gamma and delta isomers (hexachlorocyclohexane), o,p -DDT, p,p -DDE, p,p -DDD, and p,p -DDT. a-BHC and hexachlorobenzene (HCB) have a common peak. They can be separated on a column filled with 2.5% Silicone Oil XE-60 (Is-cyanoethyl-methylsilicone) on Chromosorb W (80-100 mesh). 

A workshop participant reported that China has phased out the production and use of five of the POPs covered by the Stockholm Convention—aldrin, dieldrin, endrin, toxaphene and heptachlor. He explained that chlordane and mirex are still produced in limited quantities for termite protection and hexachlorobenzene (HCB) is still produced for use as a chemical feedstock. Mirex... 

The authors also assessed the degree of equihbrium between atmospheric and aqueous PCBs and hexachlorobenzene (HCB). The ratio of absorbed amounts for SPMDs exposed to air (Af ) and water (N ) is given by... 

Hexachlorobenzene (HCB) was used as a pesticide to protect against fungus and in the manufacture of fireworks, ammunition, and synthetic rubber. This polychlorinated benzene now is foimd in coastal marine sediments. It also bioaccumulates in marine organisms. 

Molten salt is a technique that has been considered for the destruction of pesticides and other hazardous wastes for several years. In a recent study by Rockwell International for EPA (1 ), the destruction of solid hexachlorobenzene (HCB) and liquid chlordane exceeded 99.99% in a molten sodium carbonate bath at 900 to 1000°C with a residence time of 0.75 s. For the pilot-scale tests, the concentration of HCB and chlordane in the spent melt was < 1 ppm. The HCl concentration in the off-gas was < 100 ppm. 

Toxicology. Hexachlorobenzene (HCB) causes porphyria, enlarged liver and thyroid, and neurological symptoms it is a developmental toxin, and in experimental animals it is carcinogenic. 

The use of both low and high doses in a study on hexachlorobenzene (HCB) by Ezendam et al. [135] revealed the complexity of cells and mediators that participate in the response to this compound. Such approaches may provide valuable insight into gene expression changes in the presence and absence of pathological or cellular effects. 

Some substances are used to intensify the color of pyrotechnic formulations. For example, polyvinyl chloride, hexachlorobenzene (HCB) or other organic chlorides mixed with barium and copper salts are used to produce green color whereas strontium salts produce red color. 

Squalene is suggested to enhance elimination of lipophilic xenobiotics by several experimental evidences. Its nonpolar structure promotes a promising affinity for unionized drugs. Richter and Schafer (1982) studied squalene for elimination of [14C]hexachlorobenzene (HCB) as an alternative method to paraffin treatment. Animal models have been fed by squalene and paraffin as 8% of the diet. Results indicated that squalene supplementation was as effective as paraffin on fecal excretion of HCB. 

P 10.4 Assessing the Fugacities of Hexachlorobenzene (HCB) and 2,3,7,8-Tetra-chlorodibenzodioxin (2,3,7,8-TCDD) in an Agricultural Food Chain... 

P 19.2 How Fast Does a Patch of Hexachlorobenzene (HCB) Disappear from the Surface of the Ocean ... 

As a result of an accident a cloud of hexachlorobenzene (HCB) of approximatively circular shape floats in the surface-mixed layer of the ocean. At time t0 when the patch is first detected, it has approximately the shape of a two-dimensional normal distribution ... 

It remains unnoticed for several years that the pesticide hexachlorobenzene (HCB) has continuously entered the small well-mixed pond described in Illustrative Example 23.1. One day, your colleague determines the HCB concentration in the surface sediments of the pond and finds a Cf value of 1.3 nmol kg 1. You are alarmed by this value, because you fear that the HCB concentration in the water column could be dangerously high. Since you cannot get a water sample at once, you first try to calculate the concentration in the water column, C°p, by assuming a steady-state situation. From earlier investigations the following data on the sediments are available. 

Although hexachlorobenzene (HCB) was used as an active component of insecticides and fungicides in the UK until the 1970s, its major source to the environment now is now as a by-product of industrial processes such as aluminium smelting and production of perchloroethylene and vinyl chloride monomer.65 The MAFF survey mentioned earlier did not include HCB, but a later survey on milk samples from farms around potential point sources did analyse for HCB. No HCB was detected at or above the reporting limit of 1 fig/ kg in whole milk in samples from either around potential point sources or control farms.66... 

Evidence is similar for humans but limited, and includes male sterility, spontaneous abortions in human females, premature human fetuses, severe neurologic and CNS effects, blood dyscrasias, hepatotoxicity, accumulation of organohalogen pesticides in human lipid tissue—and, perhaps even more important, their presence in human breast milk, whence they can continue to exert influences on growth, development and hormonal, CNS and enzyme systems. Aldrin, dieldrin, chlordane, chlordecone (Kepone), heptachlor epoxide, hexachlorobenzene (HCB) and Mirex are all excreted via breast milk in the human female. This is also true for the related PCBs and PBBs that resist biodecomposition and maintain persistent residence in mammalian tissues. For them, excretion via breast milk may constitute the main—if not sole—elimination route. 

Hexachlorobenzene (HCB) is known to cross the rat placenta and accumulate in the fetus. Deaths of breast fed infants and an epidemic of skin sores and porphyria cutanea tarda in Turkey resulted from the accidental consumption of HCB-contaminated seed grain. The... 

TS, Summary Characterizations of Selected Chemicals of Near-Term Interest, p.25, "Hexachlorobenzene (HCB),"... 

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