Human 2,3,7,8-TCDD

Most, if not all, occupational illnesses associated with 2,4,5-T (such as chloracne) have been found to be the result of product contamination with TCDD. TCDD is extremely toxic to animals, and exposure has also been associated with liver function impairment, peripheral neuropathy, personality changes, porphyria cutanea, hypertrichosis, and hyperpigmentation in humans. TCDD is a chlorinated dioxin, one of a large number of related compounds referred to as dioxins it has no functional use and is not intentionally produced. It has been identified as the responsible toxic agent in several industrial disasters, such as accidental releases at Nitro, WV in 1949, and at Seveso, Italy in 1976. " The role of dioxin contaminants must also be considered in the discussion of 2,4,5-T toxicology. 

Much publicity has been given to 2,4,5-T. A trace impurity called 2,3,7,8-tetrachlorodibenzo-/j-dioxin (TCDD) has been called the most toxic small molecule known to humans. TCDD kills animals and causes birth defects at lower levels than any other chemical tested in the laboratoiy. In... 

Aylward LL, Hays SM. 2002. Temporal trends in human TCDD body burden decreases over three decades and implications for exposure levels. J Expo Anal Environ Epidemiol 12 319-328. 

FAS is normally characterized by growth retardation, anomalies of the head and face, and psychomotor dysfunctions. Excessive consumption of ethyl alcohol may lead to malformations of the heart, extremities, and kidneys. Since consumption of ethyl alcohol is socially acceptable and prevalent even in pregnant women, the risks associated with the use of ethyl alcohol are remarkable. However, it should be kept in mind that there are several chemical compounds in tlie occupational environment that may also cause malformations even at low doses. The oc-cupationally-important known human teratogens include methyl mercury, ethyl alcohol, PCB compounds, tobacco smoke, lead, TCDD, 2,4,5- F, carbon monoxide, nitrogen dioxide, gasoline, and fluoride. 

Poiger, H. and Buser, H.R. (1983). Structure elucidation of mammalian TCDD metabolites In Tucker, R.E., Young, A.L., and Gray, A.P. (Eds.) Human and Environmental Risks of Chlorinated Dioxins and Related Compounds. New York Plenum Press, 483 92. 

In humans and rabbits contamination of the skin with TCDD produces chloracne-like lesions (3, 4). This disease is characterized by the appearance of hyperkeratosis, papules, comedones, and cysts. 

Figure 10 illustrates the results of a typical analysis of a 10-gram sample of human milk to which 0.1 ppb TCDD has been added. Blank... 

Figure 10. TCDD recovery in 10 gram human milk to which 10 gram (0.1 ppb) TCDD was added. Each trace represents 8% of the total residue.

Polychloro-benzenes, polybromo-benzenes, and dioxins (TCDD) are among these compounds. They were discovered when the analysis techniques improved. Especially the development of GC-MS has contributed to the knowledge of the distribution of these compounds. Effects on humans are the development of chloracne, suppression of the immune system, and some compounds are probably carcinogens (Shaw 1993). As a consequence of the ubiquitous nature of PCBs, humans are exposed via many sources. 

When pushed to the limit by overriding human health concerns, residue chemists have achieved detection limits of Ippt (Ingkg ) or even into the low ppqr (1 pg kg ) range. An example at the 1 ppt level is provided by methods for 2,3,7,8-tetrachlorodibenzodioxin (TCDD) in milk and TCDD in adipose tissue. Eor relatively clean matrices such as water and air, preconcentration on solid-phase adsorbents followed by GC or gas chromatography/mass spectrometry (GC/MS) can provide detection limits of 1 ng m and less for air (examples in Majewski and Capel ) and 1 ngL and less for water (examples in Larson et A summary of units of weight and concentration used to express residue data is given in Table 1. 

The famous herbicide agent orange contained as an additive 2,3,7,8-tetrachlordibenzo-p-dioxin (2,3,7,8-TCDD), the most toxic chemical substance created by mankind. Dioxin makes up about 150-160 kg. in 24,000 tons of herbicide 2,4,5-T. This additive is enough to allow us to continue to discuss the consequences to humans and the environment in Vietnam from not one, but two wars the herbicide and the dioxin [65]. 

Although the effects of chronic exposure of humans to low levels of POPs are difficult to predict, some biological effects have been described. For example, exposure of children to PCBs and PCDD/Fs may be linked to an elevated risk for infectious diseases. Exposure of pregnant women to PCDD/Fs may cause lower fertility in their male offspring. The adverse effects to human health of acute and chronic exposure of high concentrations of POPs, especially among industrial workers exposed to daily intakes of chemicals, are more evident. Elevated concentrations of DDE and TCDD have been associated with the development of cancers such as breast cancer, leukaemia and thyroid cancer. Dioxin exposure may also be associated with immunotoxicity, reproductive diseases and neurotoxicity. Extreme exposure to chlorinated compounds has resulted in death [101]. 

Proposed 2,3,7,8-TCDD criteria for the protection of natural resources and human health... 

Table 18.7 Proposed 2,3,7,8-TCDD Criteria for the Protection of Natural Resources and Human Health...

Neubert, R., G. Golor, R. Stahlmann, H. Helge, and D. Neubert. 1992. Polyhalogenated dibenzo-p-dioxins and dibenzofurans and the immune system. 4. Effects of multiple-dose treatment with 2,3,7,8-tetrachloro-dibenzo-p-dioxin (TCDD) on peripheral lymphocyte subpopulations of a non-human primate (Callithrix jacchus). Arch. Toxicol. 66 250-259. 

Young, A.L. and L.G. Cockerham. 1985. Fate of TCDD in field ecosystems assessment and significance for human exposures. Pages 153-171 in M.A. Kamrin and P.W. Rodgers (eds.). Dioxins in the Environment. 

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