Dioxins toxicity level

Fanelb, R., M.P. Bertoni, M.G. Castelli, C. Chiabrando, G.P. Martelh, A. Noseda, S. Garattini, C. Binaghi, V. Marazza, and F. Pezza. 1980b. 2,3,7,8-Tetrachlorodibenzo-p-dioxin toxic effects and tissue levels in animals from the contaminated area of Seveso, Italy. Arch. Environ. Contam. Toxicol. 9 569-577. 

Schecter, A., et al. Congener-specific levels of dioxin and dibenzofurans in U.S. food and estimated daily dioxin toxic equivalent intake, Environ. Health Perspect., 102,962, 1994. 

According to the Bay Area Air Quality Management District in San Francisco, more than 5.5 million pounds of toxic chlorinated substances are released in the area annually. This includes approximately 13,000 pounds of chloroform, 1.4 million pounds of freon, 2 million pounds of perchloromethylene, and trace amounts of dioxin. (Dioxin is one of the most toxic chemicals known.) A report released in September 1994 by the U.S. Environmental Protection Agency (EPA) clearly describes dioxin as a serious public health threat. The public health impact of dioxin may rival the impact that DDT had on public health in the 1960s. According to the EPA report, not only does there appear to be no safe level of exposure to dioxin, but levels of dioxin and similar chemicals have been found in the U.S. population that are at or near levels associated with adverse health effects. The EPA report also confirmed that dioxin is a cancer hazard, exposure... 

Table VII compares the calculated average total dioxin toxic equivalents in human breast milk (or extrapolated from adipose tissue data) from populations in Vietnam and the United States. These numbers are based on the EPA equivalency values shown in Tables IV and V. For purposes of comparison and since the equivalent value for the north of Vietnam is the lowest we know of world-wide at the present time, we have defined this level as one. On this basis, the levels in the United States are on the average approximately 16-fold higher, while the values for south of Vietnam for 1973 and 1984 are approximately 67- and 17-fold higher respectively. It should be noted that the values for the south of Vietnam would be higher still were the data from the breast milk samples collected in 1970 (27) included in these calculations. By either calculation, there existed a population in the south of Vietnam and nursing during the early 1970 s, whose consumption of these contaminants in breast milk was quite high, and higher than any other population of nursing infants. Values from industrial countries such as the United States, Canada (Table II), or in Europe (21-23) are well above those seen in such nonindustrialized areas as the north of Vietnam, but below what was seen in heavily contaminated areas such as the south of Vietnam in 1973,...

MWCs Organic Emissions The NSPS limits organic emissions to a total dioxin plus furan emission hmit of 30 ng/dscm (at 7 percent O9 diy volume). This level is approximately equivalent to a toxic equivalent (TEQ) of 1.0 ng/dscm, using the 1990 international toxic equivalency fac tor (1-TEF) approach. 

Concern has been expressed about the possible formation of dioxins and furans. However, measurements during experiments indicated that the emissions of dioxins and furans were not significantly elevated. Dioxin emissions with or without plastic input appeared to be about a factor of 100 below the standard of 0.1 ng/Nm TEQ TCCD (toxicity equivalent in relation to the toxic dioxin TCCD) (a.7). This might be due to the benefit of the strongly reducing atmosphere and the high temperature of 2100 °C. In total, until now the conclusion has been that at current PVC levels in MSW, pretreatment for chlorine removal is unnecessary. 

Analysis of the contaminants in herring and in the seals at the end of the study revealed that PCBs accounted for the majority of Toxic Equivalents to 2,3,7,8-tetrachlo-rodibenzo-p-dioxin (TEQ). Combined with the pattern of immunotoxic effects at the level of the thymus and the T-cell, and a literature indicating an AhR-mediated immunotoxic vulnerability of the thymus [59, 60], the authors concluded that AhR-mediated effects, caused in large part by PCBs, led to the observed effects [57, 61]. They speculated that... 

The chlorinated chemicals assessed do not have the same risk profile. For the more volatile chemicals the safety margins between the actual exposure and the level at which no effect on the environment would be expected is quite high. For more persistent chemicals there is a need to look to the environmental compartment where they can be accumulated (mainly in sediments and biota). For some of these chemicals the safety margin is quite low and in worst-case situations serious effects may occur. For the very persistent, bioaccumulative and toxic chemicals (like dioxins, PCBs and DDT), acceptable environmental concentrations are so low and difficult to control that the industry is committed to reducing as far as possible releases to the environment through application of Best Available Techniques (BAT), mainly with respect to dioxins. For other chemicals (PCBs, DDT), production has already been halted for some years. 

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