Environmental Engineering Reference
In-Depth Information
The negative trend observed in the waters of Europe, USA and Brazil
is consistent with the chemical history of use. DDT was first synthesized in
1874. However, its commercial use in agricultural and sanitary pest control
started only after World War II, particularly after the 1950s. The amount
of DDT produced increased exponentially since 1950 until the 1970s.
Manufacture ceased in the western world in the 70's, due to environmental
concerns which led to restrictive legislation. The results obtained for PCB
also point to a decrease in levels. PCB production began in 1929. These
chemicals were used in hundreds of industrial and commercial applications,
as they are non-flammable, chemically stable, and have electrical insulating
properties. Their use in Europe was first regulated in 1976 when they were
restricted to closed circuits. However, PCBs were not fully banned until
1987 (UNEP 2002).Total PCB production in some of the European countries
(France, Italy and Spain) was in the range of 300.000 tn for the period
1954-84 (Tolosa et al. 1997). This was about 20% of the total worldwide
production (1500000 tn) (De Voogt and Brinkman 1989). The few studies on
temporal PCB trends in different matrices (mussels, sediment, vertebrates)
from the Northwestern Mediterranean (Tolosa et al. 1997, Villeneuve et al.
1999, Aguilar and Borrell 2004), suggest that levels are tending to decline.
The highest levels of PCBs compared to those of DDTs in northern Brazil
could be due to a several sources of this pollutant on the coast of Sao Paulo
(outputs outfall Santos Bay and an extensive industrial area (Alonso 2008)).
The exposure to considerable PCBs levels of bottlenose dolphins from
Florida coastal waters was mainly through the food web (Johnson-Restrepo
et al. 2005).
These findings indicate that apex marine predators represented
by dolphins that live in coastal and oceanic waters continue to sustain
considerable PCB exposure in the environment. Our results on bottlenose
dolphins, franciscana dolphins and harbor porpoise confi rm that PCBs and
DDTs pollution in marine environment is declining only slowly. However,
PCB decline in blubber of the species studied was found to be much less
pronounced than that of DDTs.
References
Aguilar, A. 1986. Using organochlorine pollutants to discriminate marine mammal populations:
a review and critique of the methods. Mar. Mammal Sci. 3: 242-262.
Aguilar, A. and A. Borrell. 1994. Abnormally high polychlorinated biphenyl levels in striped
dolphins (
Stenella coeruleoalba
) affected by the 1990-1992 Mediterranean epizootic. Sci.
Total Environ. 154: 237-347.
Aguilar, A. and A. Borrell. 1996. Marine mammals and pollutants, an annotated bibliography.
Barcelona: Fundacio' pel Desenvolupament Sostenible.
Aguilar, A., A. Borrell and P.J.H. Reijnders. 2002. Geographical and temporal variation in levels
of organochlorine contaminants in marine mammals. Mar. Environ. Res. 53: 425-452.
