-  climate change
 -  toxic substances
 -  ozone depletion

Toxic discharges which pollute the marine environment. ©Edwards/Greenpeace

The range and volume of chemicals that are produced today is immense. In 1995, annual worldwide chemical production stood at 400 million tonnes. Many of these chemicals are persistent, and accumulate or magnify as they move up the food chain. Such persistent substances may travel far from their origin to areas such as the Arctic and deep ocean environments. This range of chemical contaminants presents a significant threat to whales.

Of prime concern amongst such contaminants are the groups of chemicals known as persistent organic pollutants, or POPs, which include substances such as the pesticide DDT, poly-cholorinated bi-phenols (PCBs) and polycyclic aromatic hydrocarbons (PAHs).

These substances break down only very slowly, concentrating in fatty tissues, such as blubber, increasing as they move up the food chain. Consequently high levels of POPs have been recorded in whales that occupy a position near the top of the food chain, such as dolphins and other toothed whales.

Significant levels of POPs have also been recorded in certain baleen whale species in spite of the fact that they feed at lower levels within the food web. Such pollutants, known as endocrine disrupting chemicals, may disrupt naturally occurring hormones leading to reproductive and immune disorders, affecting growth and general health, and may even act as cancer causing agents in whales. Although there is little research concerning the impacts of pollutants on whales, wherever endocrine disrupting chemicals have been sought within whale tissues, they have been found.

© Greenpeace

Concerns have also been raised about the level of pollutants in Minke whales harvested by Norway and intended for export to Japan, as they contain levels of POPs and other chemicals above those permitted in food by the Japanese authorities.

A recent study of whale products available for public consumption within Japan, despite the commercial moratorium, revealed that the meat was contaminated with significant levels of PCBs, dioxins and mercury. Using DNA analysis to identify the species and origin of the whale products, revealed that half of the total sample taken from Minke whales and small whales taken from the northern hemisphere contained levels of PCBs higher than the standard permitted within Japan.

For more information about toxic substances, visit the Greenpeace toxic campaign website.