Mercury, Dieldrina and DDT, an organized insecticide widely used in agriculture in the second half of the twentieth century and whose use is prohibited in Spain since 1973. They are some of the pollutants that a group of researchers from the University of Santiago de Compostela has found in the feathers of the White Camping. They analyzed Samples collected in 23 nests from 10 locations in Galicia and discovered the presence of 11 different pesticides, 88.3% of which are already prohibited. The herbicide attracts, for example, was found in eight locations despite being prohibited in the EU since 2004.
«Ciconia Ciconia is a good biomonitor, because it is associated with agricultural areas. Cultivation fields choose to feed in insects … »comments Zulema Varela, principal researcher of this study that has just presented their conclusions. She works in biomonitoring of environmental pollution at the University of Santiago and, in addition, she is a member of friends das Cugoñas (friends of the stork in Galician). A year ago, he presented with his team another study in which they investigated the presence of plastics and microplastics in their nests, «Because these birds take everything around. We analyze both nests and egagropys (the balls of non -digested remains that regurgate certain species of birds like this), ”he says.
However, on this occasion they have wanted to analyze the presence of those toxins that are not seen as the phytosanitary used in the field or the presence of heavy metals of those who have found worrying traces.
One of the parties that stands out of your research is the relationship between each pollutant and the type of main activity that is carried out in the area. «We try to see if there is rconnection between pesticides and crop types and we have seen that in the areas of potatoes or corn, the stork presented a chemical profile different from other regions with livestock or garden. Thus, in areas like Monforte de Lemos and Maceda they were recorded up to seven different prohibited pesticides. On the other hand, mercury was more frequently detected in regions with intensive agriculture, decreasing in traditional livestock areas, ”he says.
The main problem, the team points out, is the persistence of these pollutants in the environment and that are bioacumulative. «Pesticides that were used many years ago are still present in vegetation, in the ground and, in the end, the fauna ends up incorporating it. They are practically everywhere, even in Antarctica. The fact that we have found remittage remains such as The prohibited DDT so many years tells us about the time it takes to disappear And we also have to worry, because there are still countries where these substances are still being used. Understanding the persistence of these toxic and their effects on wildlife is key to developing more effective environmental policies because there is a risk of a reentry in trophic networks with the mobilization of contaminated soils or their atmospheric redistribution, ”adds Zulema Varela.
In this sense, the researcher speaks of the limited effect of the prohibitions in the EU for the use of certain chemicals, while it is still used in third countries of which products are then imported or from which migrant species return. In addition, it suspects that “it is likely that some of these prohibited substances continue to be used in Spain, because birds such as the storks are increasingly migrating to Africa.”
Effects also on humans
Toxins accumulate in animals organisms, especially in fatty tissues and especially in those found at the top of the trophic chain, causing neurological or reproductive problems among others. In Spain there are DDT biomonitoring studies that show that this compound is present in our blood.
Carlos de Prada, a naturalist and communicator specializing in pollutants, remembers other studies that talk about the consequences of these pollutants in the populations of wildlife: «Years ago it was investigated in Doñana and some unexpectedly high levels of DDT and PCB (polyclorinated biphenyls, another persistent pollutant) were found in the eggs of the royal millns. In 50% of the eggs, the DDT was at levels associated with reproductive damage in raptors. In the case of PGB, also the levels found can be associated with less success in hatching, to death in embryos and appearance of deformities in chickens born to those eggs. Some of these substances have been used massively and have contaminated the environment globally. They were prohibited from their high persistence and by causing devastating effects in some populations: in fact, it almost ended the entire population of the US pilgrim from the US. The females began to incubate and when they put on top of the eggs, they broke them because they had the extraordinarily thin shell due to hormonal alterations, ”he says.
A long history
It was the year 1962 when the book was published Silent spring. In him, the American biologist Rachel Carson -who, by the way, died of breast cancer -denounced for the first time the effects of these chemicals. «Researchers have been seeing a series of alterations in wildlife for years. In southern California, seagull males were feminized: they had female cells in the testicles due to endocrine disruption produced by agricultural pollutants, ”continues Prada.
Despite its prohibition, the DDT is found «not in great concentrations, but in traces, in 80% of the soil samples and in a 75% sediments we study ». Who speaks is Miguel Muñoz, coordinator of the Librara campaign from Seo Birdlife.
The NGO has studied the presence of pollutants in soils, waters and sediments in 140 of the 450 important spaces For birds in Spain (important places that have no protection figure).
From his research, for example, they found no sample (or area) not impacted by pollutants. «Of all water samples we only find four places that did not present any pollution. In the rest of the samples, we find remains of up to 21 drugs, 17 pesticides and 17 compounds present in the manufacture of plastic, ”says Miguel Muñoz.
These pollutants, which the animal cannot excrete, accumulate above all its fatty tissue so even small concentrations with a long exposure can end up generating high toxicity levels causing problems of all kinds, such as fertility. «We find mercury, lead, nicotine, flame retardants. A single button can contaminate up to 20 liters of water and where it appears, water fleas that are one of the basic foods of the trophic chain do not grow because it feeds the entire pyramid, ”says Libera coordinator. The next step is to analyze throughout the territory the presence of these pollutants in the main communities of wildlife.
Travelers chemicals
The fact that they are not used in Europe does not mean that they do not occur and then export them, denounce NGOs such as Greenpeace, which in 2018 warned of the export of more than 81,000 tons of chemicals by EU companies. In addition, Carlos de Prada clarifies, “the pesticides that are used now, although they are less persistent, are also harmful for their cumulative effect.”
In this sense, a 2022 study of the Spanish Food and Nutrition Security Agency found remains of chemical pollutants in 43% of fruit and vegetables (they analyzed 1,743 food samples). In tomatoes they found 31 pesticides; 19 possible endocrine disruptors, in apples; 22 phytosanitary, in oranges and tangerines another 22; and 21 different products in lettuce.