owing to their persistency and toxic accumulation in the ecosystem. This class of
persistent compounds include polychlorinated biphenyls (PCBs), polychlorinated
dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), benzo(a)pyrene (BaP), hexachlorobenzene (HCB), polychlorinated naphthalene,
octachlorostyrene, 1,1,1-trichloro-2,2-diethane, alkyl-lead pesticides such as mirex,
dieldrin, aldrin, chlordane and toxaphene. Of these POPs, PCDDs, PCDFs and PCBs
(dioxin-like compounds) are the three prime categories of dioxins and furans that
have gained importance in the scientific community.
PCDDs/PCDFs and PCBs are the most dangerous anthropogenic toxicants since
these chemicals have a widely reported environmental damage history over the past
few decades and also highlighted as “the most toxic man-made chemical” ever made.
PCDDs and PCDFs are two classes of planar polycyclic halogenated aromatic
hydrocarbons with a total of 410 different compounds, only 30 of which are
considered to be significant congeners. The characteristic of the congeners is certain
to depend on the nature, position and number of halogen atoms bound to the
aromatic carbon rings; one such classic example is 2,3,7,8-tetrachlorodibenzo-pdioxin (2,3,7,8-TCDD), chlorine substituted in the 2, 3, 7, and 8 positions of the
aromatic benzene ring, which is the most toxic congeners. 2,3,7,8-TCDDs are
known for its lowest lethal dose median (LD 50 ) among the dioxin family in male
guinea pigs which is nearly 1 μg/kg of body. Dioxins/furans were not produced or
created intentionally for market value but were the by-products of several industrial
processes and combustion techniques. An example of such a phenomenon is the
burning of plastic which contains chlorinated phenolic compounds that release
dioxins and are termed to be accidental contaminants. Due to the accumulation of
members of dioxins family in the fat tissues and thereby entering the food chain,
efforts are being made to minimize the exposure of such chemicals into the
environment.
Since the nineteenth century, there has been an incidence of dioxin and furan
pollution from industries. German industrial workers were overexposed to 2,3,7,8TCDD or dioxin that resulted in chloracne, oozing skin lesions. During the Vietnam
War (1965–1971), United States (US) military sprayed herbicide dubbed Agent
Orange as a defoliant, which was contaminated with 2,3,7,8-TCDD and showed
serious health effects. Dioxin pollution and its ill effects came to public attention
after the explosion of Industrie Chimiche Meda Societa Anonima (ICMESA) chemical factory in Seveso, Italy, in 1976. Boda et al. (2018) demonstrated the
associations of dioxins in breast milk and cord blood sex hormones in Vietnamese
newborn infants residing near the former US Air Force base. TCDD has the highest
degree of toxicity rated 1 (reference value), while others are less toxic. In 2005, the
World Health Organization (WHO) re-evaluated the toxic equivalency factor (TEF)
values defined on the 1998 WHO-TEF value for human risk assessment (Van den
Berg et al. 2006). According to Ren and Zheng (2009), the differences between
dioxin and furan estimation with each unit should not exceed 28%. Reduction in
levels of dietary dioxins/furans in food sources between 1998 and 2018 was
observed in the general population of Spain (González et al. 2018).
396
J. G. A. Jeno et al.
persistent compounds include polychlorinated biphenyls (PCBs), polychlorinated
dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), benzo(a)pyrene (BaP), hexachlorobenzene (HCB), polychlorinated naphthalene,
octachlorostyrene, 1,1,1-trichloro-2,2-diethane, alkyl-lead pesticides such as mirex,
dieldrin, aldrin, chlordane and toxaphene. Of these POPs, PCDDs, PCDFs and PCBs
(dioxin-like compounds) are the three prime categories of dioxins and furans that
have gained importance in the scientific community.
PCDDs/PCDFs and PCBs are the most dangerous anthropogenic toxicants since
these chemicals have a widely reported environmental damage history over the past
few decades and also highlighted as “the most toxic man-made chemical” ever made.
PCDDs and PCDFs are two classes of planar polycyclic halogenated aromatic
hydrocarbons with a total of 410 different compounds, only 30 of which are
considered to be significant congeners. The characteristic of the congeners is certain
to depend on the nature, position and number of halogen atoms bound to the
aromatic carbon rings; one such classic example is 2,3,7,8-tetrachlorodibenzo-pdioxin (2,3,7,8-TCDD), chlorine substituted in the 2, 3, 7, and 8 positions of the
aromatic benzene ring, which is the most toxic congeners. 2,3,7,8-TCDDs are
known for its lowest lethal dose median (LD 50 ) among the dioxin family in male
guinea pigs which is nearly 1 μg/kg of body. Dioxins/furans were not produced or
created intentionally for market value but were the by-products of several industrial
processes and combustion techniques. An example of such a phenomenon is the
burning of plastic which contains chlorinated phenolic compounds that release
dioxins and are termed to be accidental contaminants. Due to the accumulation of
members of dioxins family in the fat tissues and thereby entering the food chain,
efforts are being made to minimize the exposure of such chemicals into the
environment.
Since the nineteenth century, there has been an incidence of dioxin and furan
pollution from industries. German industrial workers were overexposed to 2,3,7,8TCDD or dioxin that resulted in chloracne, oozing skin lesions. During the Vietnam
War (1965–1971), United States (US) military sprayed herbicide dubbed Agent
Orange as a defoliant, which was contaminated with 2,3,7,8-TCDD and showed
serious health effects. Dioxin pollution and its ill effects came to public attention
after the explosion of Industrie Chimiche Meda Societa Anonima (ICMESA) chemical factory in Seveso, Italy, in 1976. Boda et al. (2018) demonstrated the
associations of dioxins in breast milk and cord blood sex hormones in Vietnamese
newborn infants residing near the former US Air Force base. TCDD has the highest
degree of toxicity rated 1 (reference value), while others are less toxic. In 2005, the
World Health Organization (WHO) re-evaluated the toxic equivalency factor (TEF)
values defined on the 1998 WHO-TEF value for human risk assessment (Van den
Berg et al. 2006). According to Ren and Zheng (2009), the differences between
dioxin and furan estimation with each unit should not exceed 28%. Reduction in
levels of dietary dioxins/furans in food sources between 1998 and 2018 was
observed in the general population of Spain (González et al. 2018).
396
J. G. A. Jeno et al.