Environmental Engineering Reference
In-Depth Information
14.1.2 Birds, Mammals, Pesticides, and Biomarkers
There are about 2,000 genera and 10,000 species of birds in the Aves class, and approxi-
mately 1,200 genera and 5,500 species of mammals in the Mammalia class. With such num-
bers, it is not surprising that they possess a wide array of life history strategies, and both
classes inhabit the ecosystems across the globe, including the oceans and the Arctic and
Antarctic regions. Raptorial and fish-eating birds and cetaceans, pinnipeds, and mustelids
are the most classic groups used as environmental sentinels for monitoring pesticides and
other contaminant residues (Sheffield 1997; Newton 1998; Ross 2000; Burger and Gochfeld
2004; Hollamby et al. 2006; Helander et al. 2008; Grove et al. 2009), although in a few cases
with some unnecessary controversy (Basu et al. 2007, 2009; Bowman and Schulte-Hostedde
2009). Most of these animals have long lifespans, so pollutant burdens may be integrated
in some complex way over time. In addition, the conservation of biodiversity is becoming
an integral part of the sustainable management of ecosystems, so almost any bird or mam-
mal species can also be used as primary or surrogate receptor species in the environmen-
tal risk assessments by themselves (Strause et al. 2007).
The most persistent (and most analyzed) pesticides are ubiquitous and may appear in
environments such as the Arctic, Antarctic, and other remote and cold areas such as high
altitude mountains that had never been treated with these chemicals (Cipro et al. 2010;
Rigét et al. 2010). This is especially true for the so-called persistent organic pollutants
(POP), a group of carbon-based chemicals characterized by their low solubility in water,
semivolatility, and resistance to photolytic, chemical, and biological degradation (Jones and
de Voogt 1999; El-Shahawi et al. 2010). The combination of these chemical and physical
properties facilitates long half-lives in the environment and their long-range transport pro-
cesses, notably by the “global-distillation” mechanism, in which these compounds evapo-
rate in warmer regions (where they were or are produced or used) and are transported
by the atmosphere to cooler regions of the world (by higher altitude or latitude), where
POPs condense and therefore enter the food web (Braune et al. 2005; Bhatt et al. 2009). By
contrast, for most polar POPs, transport by ocean currents may also play an important role
(Lohmann et al. 2007). All these pollutants are also known for their ability to bioconcentrate
(or bioaccumulate) and biomagnify (or bioamplify) under environmental conditions due
to their lipophilic structures and resistance to metabolism, thereby potentially achieving
toxicologically relevant concentrations in some animal groups, especially those situated at
the top of the food web via trophic transfer (Jones and de Voogt 1999; Braune et al. 2005).
The “classical” POPs (informally called the “dirty dozen”) were 12 chemicals addressed
by the Stockholm Convention on Persistent Organic Pollutants of 2001 and include eight
intentionally produced OC insecticides (aldrin, chlordane, 1,1,1-trichloro-2,2-di(4-chlorophe-
nyl)ethane (p,pʹ-DDT), dieldrin, endrin, heptachlor, mirex, and toxaphene) and the polychlo-
rinated biphenyls (PCBs), the two unintentionally produced substances polychlorinated
dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF), and HCB, which
had both origins (intentional as a fungicide and nonintentional as a byproduct in industrial
processes) (Zitko 2003a,b; Lohmann et al. 2007; El-Shahawi et al. 2010). This international
treaty, which aims to eliminate or restrict the production and use of these POPs, can be
traced in its origins to the Rachel Carson's classic 1963 topic Silent Spring, which alerted
the public to the toxic side effects of OC insecticides such as DDT and its derivatives, with
innovative and even provocative new concepts (Burger 1997; Pollock 2001; Rattner 2009).
However, the use of DDT is still “tolerated” in a few countries in Africa, Asia, and Latin
America for the control of malaria (Turusov et al. 2002), as a total ban has been demon-
strated in an increase of this vector-transmitted illness (Attaran and Maharaj 2000).
Search WWH ::
Custom Search