The M
arine Pollution Symposium taking place in Monaco this week is being attend by
scientists who deal with shocking problems on a regular basis. Half way through the symposium, delegates have become more bold and willing to debate.The week began quaintly, but the aura of détente has subsided. A
popular saying "I was not content with your explanation" proceeds polite abuse of the speaker's work. So far no blows other than verbal have been exchanged.
In a survey of popular destinations, only the scientific community would place the Arctic high on their list. The remote and until recently pristine character of the
northern seas make them ideal for field studies. More importantly, scientists are interested in understanding how persistent long-lived pollutants such as
polychlorinated biphenyls (PCBs), dioxins as well as DDT and other pesticides are spreading throughout the globe. The remote character of the Arctic combined with its
proximity to Northern Europe and Asia industries make it a good choice for studies.
Regina Bruhn from the Institute for Marine Research in Kiel, Germany, made a
presentation on studies to examine the population of the harbor porpoise in the Baltic Sea. Over the last three decades their populations have been declining and Bruhn's work attempts to quantify a pollutant influence.
Bruhn's research compared PCB levels of porpoises living in the Baltic and North Sea against those in the Arctic Sea. These comparisons can help determine the extent that
PCBs are being distributed via the atmosphere all over the globe.
Results show some surprising answers. Total levels of PCBs from lower latitude
porpoises were about 10 times higher than those of the Arctic, as expected. This may indicate that PCBs are not being readily distributed into the far north seas. After closer
examination however, Bruhn determined PCBs with low chlorine substitutions (low chlorinated PCBs) were in higher concentrations in the Arctic species.
The accumulation of PCBs with low chlorine substitutions signifies a potential toxic problem in theses animals. Porpoise and other Arctic mammals do not have a natural
means to excrete the low chlorinated PCBs, their metabolism lacks the proper enzymes to break them down. According to, and co-author, Dr. Kannan "these residues may, in time, accumulate to a level to exert a toxic response."
In addition, Bruhn also studied DDT, a pollutant with "extremely high acute chronic toxicity." She noted that findings on DDT in the porpoise's blubber indicate there is an
unknown fresh source of DDT entering the Arctic Sea. Factoring out atmospheric transport of the DDT, it seems apparent that DDT is making its way into the Arctic Sea via an undetermined man-made input.
Mother's Watch Program
In a shocking report from Mexico, Dr. Vazquez-Botello of the University of Mexico Institute de Ciencias del Mar y Limnologia told the symposium that high
concentrations of the (U.S. banned) pesticide DDT are showing up in the breast milk of some mothers in south east Mexico.
Botello has been studying pesticides like DDT and other since 1988. Although DDT has
been banned in most industrialized nations, Mexico produces about 4,000 tons of the chemical annually. Botello's work testing oysters for accumulation of DDT led him to
studies being performed on "mother's milk." His review of the data indicates extremely high levels of DDT, in some cases 20 times higher than what is considered safe. He said
the women affected are those "living in rural areas where the main activity is agriculture. They are in close contact with the dispersion of the use of the pesticide."
Hopes are to set-up a Mother's Watch Program where the breast milk in areas considered potentially unsafe is tested for DDT. Similar programs have been
established in areas such as the Netherlands and Germany for other toxic pollutants. Mexico has plans to reduce production of DDT due to NAFTA regulations by the year 2000.
