Encontrados niveles elevados de compuestos tóxicos en las costas de Africa Occidental/High levels of toxic compounds found on coasts of West Africa

Un equipo científico internacional ha encontrado concentraciones muy elevadas de bifenilos policlorados (PCB) a lo largo de las costas de Africa occidental. La producción de estos compuestos extremadamente tóxicos está prohibida desde hace años en Europa y en Estados Unidos. Su origen podría ser el vertido ilegal de residuos or un enorme cementerio de barcos en Mauritania.
Los PCBs, sustancias cancerígenas según muchos estudios, se emplearon antaño como líquidos aislantes en transformadores, condensadores y como refrigerantes de diversos aparatos. Sin embargo, su producción fue prohibida en Estados Unidos en 1979 debido a su toxicidad y persistencia en el medio ambiente, y a partir de 2001 se prohibieron en aquellos que, paises como España, firmaron el Convenio de Estocolmo sobre Compuestos Orgánicos Persistentes.
Ahora un equipo liderado por Rosalinda Gioia de la Universidad de Lancaster (Reino Unido) ha encontrado elevadas concentraciones de PCB (entre 10 y 360 picogramos/m3) en algunos paises de Africa occidental, como Gambia y Costa de Marfil, y a lo largo de toda la costa.
Según Gioia, los niveles tan altos de PCB's podrían venir de más de una fuente potencial: el gran cementerio de barcos de la bahía de Nuadibú (Mauritnia) o la quema de material orgánico en incendios forestales en la región, aunque esta fuente puede ser eliminada ya que en esos casos también se producen otros contaminantes (hidrocarburos aromáticos policíclicos, PHA) que no han sido detectados en este caso.

An international team of scientists has found very high levels of polychlorinated biphenyls (PCBs) along the coasts of West Africa. Production of these extremely toxic compounds has been banned in Europe and the United States for years. These harmful substances could come from the illegal dumping of waste or from an enormous ship breaking yard in Mauritania.
PCBs, which some studies have shown to be carcinogenic compounds, were used years ago as dielectric fluids in transformers, condensers and coolants for various devices. However, their production was banned in the United States in 1979 due to their toxicity and persistence in the environment, and they were banned from 2001 onwards in countries such as Spain that signed up to the Stockholm Convention on Persistent Organic Compounds.
Now, the team led by researcher Rosalinda Gioia at Lancaster University (United Kingdom), has shown that high concentrations of PCBs (between 10 and 360 picograms/m3) are found in some countries in West Africa, such as the Gambia and Ivory Coast, and all along this coast.
Gioia explains that the high levels of PCBs could come from more than one potential source: The large ships' graveyard in the bay of Nuadibú (Mauritania) or the burning of organic material from forest fires in the region, but this source can be ruled this out because such cases also release other contaminants (PAHs, polycyclic aromatic hydrocarbons) not detected in this case.

Tomado de/Taken from Plataforma SINC

Resumen de la publicación/Abstract of the paper
Evidence for Major Emissions of PCBs in the West African Region
Rosalinda Gioia, Sabine Eckhardt, Knut Breivik, Foday M. Jaward, Ailette Prieto, Luca Nizzetto, and Kevin C. Jones
Environ. Sci. Technol., 2011, 45 (4), pp 1349–1355
DOI: 10.1021/es1025239
Abstract
In previous studies unexpectedly high air concentrations of polychlorinated biphenyls (PCBs) were observed in ship-based measurements made 400 km off parts of the West African coast. To investigate further (i) samples were taken on board the RV Polarstern during a cruise from Germany to South Africa in October−November 2007; (ii) samples were obtained on Cape Verde Island during the same period to monitor airflows from Africa; and (iii) passive samplers were deployed in four West African countries to try to characterize potential sources on land. Results were as follows: on Cape Verde and on the ship air masses came predominantly ( 95%) from the African continent; the shipboard Σ29PCB concentrations off West Africa ranged from 10 to 360 pg m−3 and from 6 to 99 pg m−3 in Cape Verde; the highest land-based concentrations were observed in Ivory Coast and the Gambia (up to 300 pg m−3) and the lowest was observed in Ghana (9 pg m−3). Taken together, these and previous studies indicate there are more major emission(s) of PCBs and different source types in parts of West Africa than accounted for in current global atmospheric emissions estimates. Results from the FLEXPART model and PAH measurements show that emission inventories and biomass burning cannot fully explain the high PCB concentrations. Potential sources of the high PCB levels to the African regions are discussed, namely illegal dumping of PCB containing waste with release via volatilization and uncontrolled burning, and the storage and breakup of old ships.