70
3.4.4 Effects on Immune System
The immune system is predisposed to any external insults including xenobiotics
(Blanco 2011). Impairment of immune system of vertebrates by organophosphate/
carbamates has been evidenced by a number of research works in the past decades
(Wong et al. 1992; Barnett and Rodgers 1994; Vial et al. 1996; Zhuang et al. 2015).
Decreased humoral and cell-mediated response and nonspecific immunity, along
with increment in hypersensitivity and autoimmunity, are some immunotoxic effects
induced by organophosphate agents (Shahzad et al. 2015). Normal functioning of
immune system is impeded through anticholinergic as well as non-cholinergic pathways by organophosphate (Barnett and Rodgers 1994; Vial et al. 1996).
Anticholinesterase-induced oxidative stress and immunomodulation are well established in mammalian models (Cabello et al. 2001; Galloway and Handy 2003;
Abdollahi et al. 2004; Polláková et al. 2012; Watanabe et al. 2013). Unfortunately,
very little information is available about organophosphate-/carbamate-induced
immunotoxicity in non-mammalian models like birds. Cupic Miladinovic et al.
(2018) have suggested that chloropyriphos-induced oxidative stress in Japanese
quail may be responsible for inflammatory responses. Immunosuppressive effects
like reduced lymphocyte proliferation and reduced functional status of phagocytic
cells have been found in carbaryl-treated chicken (Singh et al. 2007). Young chicks
when exposed to sublethal dose of chloropyriphos and methidathion resulted in
reduction of total count of WBC, neutrophils, and lymphocyte (Obaineh and
Matthew 2009). In the study of Shahzad et al. (2015), there was increased proliferation of interfollicular connective tissue, cytoplasmic vacuolation, oedema, and
appearance of pyknotic and fragmented nuclei (marker for degeneration that
depleted the frequency of lymphoid follicles in bursa of Fabricius in chlorpyrifostreated chicks at sublethal dose). Similar degenerative pathologies were also found
in spleen and thymus of the treated chickens.
3.5 Pesticides and Birds
In northern Europe and North America, many grassland or farmland bird species are
known to undergone population declines in the past five decades (Mineau and
Whiteside 2013). Reports from various survey analyses indicated that grassland
birds of North America as a group are declining faster than birds from other biomes
(Dunn et al. 2000; Sauer et al. 2000; Bird Life International 2013). During
1971–1975 after introduction of organophosphate in the UK, a series of incidents
involving mortality of birds have followed after application of herbicides and insecticides for agricultural intensification in UK, primarily via indirect, food-mediated
effects (Campbell and Cooke 1997; Potts 1997). Following consumption of coated
seeds with carbofenothion resulted in mass mortality of greylag geese (Anser anser)
and pink-footed geese (Anser brachyrhynchus) in the UK, assumed to be around 1%
A. Mitra et al.
3.4.4 Effects on Immune System
The immune system is predisposed to any external insults including xenobiotics
(Blanco 2011). Impairment of immune system of vertebrates by organophosphate/
carbamates has been evidenced by a number of research works in the past decades
(Wong et al. 1992; Barnett and Rodgers 1994; Vial et al. 1996; Zhuang et al. 2015).
Decreased humoral and cell-mediated response and nonspecific immunity, along
with increment in hypersensitivity and autoimmunity, are some immunotoxic effects
induced by organophosphate agents (Shahzad et al. 2015). Normal functioning of
immune system is impeded through anticholinergic as well as non-cholinergic pathways by organophosphate (Barnett and Rodgers 1994; Vial et al. 1996).
Anticholinesterase-induced oxidative stress and immunomodulation are well established in mammalian models (Cabello et al. 2001; Galloway and Handy 2003;
Abdollahi et al. 2004; Polláková et al. 2012; Watanabe et al. 2013). Unfortunately,
very little information is available about organophosphate-/carbamate-induced
immunotoxicity in non-mammalian models like birds. Cupic Miladinovic et al.
(2018) have suggested that chloropyriphos-induced oxidative stress in Japanese
quail may be responsible for inflammatory responses. Immunosuppressive effects
like reduced lymphocyte proliferation and reduced functional status of phagocytic
cells have been found in carbaryl-treated chicken (Singh et al. 2007). Young chicks
when exposed to sublethal dose of chloropyriphos and methidathion resulted in
reduction of total count of WBC, neutrophils, and lymphocyte (Obaineh and
Matthew 2009). In the study of Shahzad et al. (2015), there was increased proliferation of interfollicular connective tissue, cytoplasmic vacuolation, oedema, and
appearance of pyknotic and fragmented nuclei (marker for degeneration that
depleted the frequency of lymphoid follicles in bursa of Fabricius in chlorpyrifostreated chicks at sublethal dose). Similar degenerative pathologies were also found
in spleen and thymus of the treated chickens.
3.5 Pesticides and Birds
In northern Europe and North America, many grassland or farmland bird species are
known to undergone population declines in the past five decades (Mineau and
Whiteside 2013). Reports from various survey analyses indicated that grassland
birds of North America as a group are declining faster than birds from other biomes
(Dunn et al. 2000; Sauer et al. 2000; Bird Life International 2013). During
1971–1975 after introduction of organophosphate in the UK, a series of incidents
involving mortality of birds have followed after application of herbicides and insecticides for agricultural intensification in UK, primarily via indirect, food-mediated
effects (Campbell and Cooke 1997; Potts 1997). Following consumption of coated
seeds with carbofenothion resulted in mass mortality of greylag geese (Anser anser)
and pink-footed geese (Anser brachyrhynchus) in the UK, assumed to be around 1%
A. Mitra et al.