308
properties of PFAS, production of PAFS is being made on a large scale so that it can
be used in industrial and consumer products. Buch described the classification and
terminologies of the PFAS in 2011 as it belongs to a vast class of the compounds
[8]. From point of view of regulations, PFSAs and perfluoroalkyl carboxylic acids
(PFCAs) that are long-chain PFASs lie in the area of interest. PFASs are considered
environmental pollutants, and therefore some manufacturers from the Western
countries have stopped their production or halted production or decided to phase out
perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) manufacturing in
the 2000s. Still, PFASs are detected in humans and wildlife commonly due to continuous manufacturing as well as less biodegradability and because of the production of some other PFASs compounds [45]. The most important source of human
exposure to the PFAS is diet such as eggs, fish, and meat [57]. Another source of
human exposure to PFAS is indoor dust [58]. Before birth, human exposure to PFAS
occurs because of placental transfer [59]. Due to the high immune-toxicants susceptibility, exposure to prenatal toxicants has been considered of great importance
because of the in-utero development of the immune system [60, 61]. Besides early
childhood complications, toxicant’s exposure to the fetus may cause changes
throughout life constantly, which may lead to immune diseases and cancers [62].
Rodent studies have indicated that PFASs also exhibit immunotoxic effects. For
example, DeWitt explained how the level of IgM antibodies was suppressed after
exposure to the PFASs [63]. Peden-Adams described that antibody production was
affected by PFOS [64]. The collective facts on rodent studies suggest that the production of antibody is an important endpoint that is sensitive to PFAS exposure [65].
In recent studies, it has been reported that PFASs exposure causes immunotoxic
effects in humans. A connection between increased PFAS concentration in blood
and decreased humoral immunity has reported. Furthermore many other studies
have not suggested any relationship between infectious and allergic responses and
PFAS exposure [66]. Evidence of immune-suppression has reported by Granum in
prenatal childhood exposure, for example, inverse relationship between the concentration of four PFAS in maternal serum at delivery time and levels of anti-rubella
antibodies in the serum sample of 3 years old kid. During the period of the first
3 years of life, a positive connection was found between the maternal concentration
of PFASs and the number of episodes of gastroenteritis and the common cold [67].
It is concluded that early childhood exposure to PFAS causes immunesuppression [68].
International Concerns
In the early 2000s, international concern began regarding potential effects to healthrelated to PFASs exposure when polar bear blood was detected with PFOS in wildlife, arctic, and other remote regions [48]. Initial data on bioaccumulation of PFOS
in marine food chains showed the susceptibility of human exposure to PFASs by
seafood [69]. Disease control and prevention of the U.S., i.e. Centers for Disease
S. G. Niazi et al.
properties of PFAS, production of PAFS is being made on a large scale so that it can
be used in industrial and consumer products. Buch described the classification and
terminologies of the PFAS in 2011 as it belongs to a vast class of the compounds
[8]. From point of view of regulations, PFSAs and perfluoroalkyl carboxylic acids
(PFCAs) that are long-chain PFASs lie in the area of interest. PFASs are considered
environmental pollutants, and therefore some manufacturers from the Western
countries have stopped their production or halted production or decided to phase out
perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) manufacturing in
the 2000s. Still, PFASs are detected in humans and wildlife commonly due to continuous manufacturing as well as less biodegradability and because of the production of some other PFASs compounds [45]. The most important source of human
exposure to the PFAS is diet such as eggs, fish, and meat [57]. Another source of
human exposure to PFAS is indoor dust [58]. Before birth, human exposure to PFAS
occurs because of placental transfer [59]. Due to the high immune-toxicants susceptibility, exposure to prenatal toxicants has been considered of great importance
because of the in-utero development of the immune system [60, 61]. Besides early
childhood complications, toxicant’s exposure to the fetus may cause changes
throughout life constantly, which may lead to immune diseases and cancers [62].
Rodent studies have indicated that PFASs also exhibit immunotoxic effects. For
example, DeWitt explained how the level of IgM antibodies was suppressed after
exposure to the PFASs [63]. Peden-Adams described that antibody production was
affected by PFOS [64]. The collective facts on rodent studies suggest that the production of antibody is an important endpoint that is sensitive to PFAS exposure [65].
In recent studies, it has been reported that PFASs exposure causes immunotoxic
effects in humans. A connection between increased PFAS concentration in blood
and decreased humoral immunity has reported. Furthermore many other studies
have not suggested any relationship between infectious and allergic responses and
PFAS exposure [66]. Evidence of immune-suppression has reported by Granum in
prenatal childhood exposure, for example, inverse relationship between the concentration of four PFAS in maternal serum at delivery time and levels of anti-rubella
antibodies in the serum sample of 3 years old kid. During the period of the first
3 years of life, a positive connection was found between the maternal concentration
of PFASs and the number of episodes of gastroenteritis and the common cold [67].
It is concluded that early childhood exposure to PFAS causes immunesuppression [68].
International Concerns
In the early 2000s, international concern began regarding potential effects to healthrelated to PFASs exposure when polar bear blood was detected with PFOS in wildlife, arctic, and other remote regions [48]. Initial data on bioaccumulation of PFOS
in marine food chains showed the susceptibility of human exposure to PFASs by
seafood [69]. Disease control and prevention of the U.S., i.e. Centers for Disease
S. G. Niazi et al.