It has been almost 50 years since the controversial book by Rachel Carson, "Silent Spring" alerted the world about the harmful effects of DDT on the environment. The success of the publication triggered an intense investigation on DDT that led to its ban in 1969.Since then, pesticide use has ido decreasing gradually in all countries of the world in favor of less dangerous alternatives.

However, the six decades of widespread use of insecticide seem to have left their mark on the glaciers of Antarctica. This conclusion is clear from the survey conducted by biologist Heidi Geisz, the Institute of Marine Science in Gloucester, who has found that pollution levels of penguins in Antarctica Adelaide residents are the same as several decades ago. The surprise came to see that the remaining species coexist in habitat have much lower rates toxic. To explain, Geisz has formulated a scenario which states that Adelaide penguins are the only animals that do not conduct the study any migration throughout the year, suggesting that the source of contamination was found in the ice itself. It seems obvious that birds are not exposed to the same source of infection in the past, because the parameters of dissemination of DDT have fallen from 36,000 tones a year of the sixties to 1,000 tons occurring at present. "The penguins are not exposed to new sources of pesticides, but surely to deposit the same in the ice-believes the marine biologist-but we have also found other toxic chemical worse than the same DDT. The research team has also pointed out that this "thaw toxic 'will be accelerated by global warming," because the temperature in the area has risen 6th in recent years, and will continue to rise.

The pesticide under suspicion

DDT is an organ chlorine insecticide well known for being the most famous of contaminated with persistent organic pollutants. Several studies have demonstrated their harmful effects on the Earth's atmosphere, the human nervous system and the reproductive process of many animal species. Its use was officially banned in 1972 by the Environmental Protection Agency United States, as a "chemical with great potential carcinogenic to humans". However, is very effective to stop transmitted by insect pests, such as malaria. In 2006 the World Health Organization (WHO)-which has catalogued the insecticide as "moderately hazardous" - reopened the debate about its use by announcing that DDT would be part of its plan to eradicate malaria in the tropics.

Some supporters of insecticide, as the Danish scientist Bjørn Lomborg, argue that it was achieved thanks to eliminate malaria in Greece and Italy, areas where the disease was endemic. In addition, the chemical has a very low production costs and, most importantly, has no problems with patents for their manufacture. In fact, some researchers have pointed out that behind the campaign against DDT might be the chemical industry itself, eager to impose on the market new products registered by their companies.