Nature Reviews Cancer publishes an article by Brazilian researchers mapping the distribution of pollution around the world and showing that the countries with the worst air quality also have the fewest scientific production on the subject (ABr)

Less science, more pollution

October 9, 2013

By Karina Toledo, Caxambu

Agência FAPESP – Universidade de São Paulo researchers have published a detailed map of atmospheric pollution, showing that the countries with the worst air quality indices are precisely those with the fewest scientific production on this topic. The article was published in the August edition of Nature Reviews Cancer.

In the opinion of the article’s author, Lais Fajersztajn, lead researcher of the FAPESP-funded study, the result indicates that science is an important tool for improving atmospheric pollution and must be strengthened in developing countries through international collaboration. “The greater the knowledge, the better it is disseminated, and the more chances there are of dealing with the problem,” she stated.

For purposes of comparison, the researchers cross-referenced data on the population density and atmospheric pollution available on the World Bank’s website with the Web of Science database, an online index produced by Thomson Reuters.

Although developed countries, such as the United States, Canada and the majority of European nations, had high pollution indices (between 5 and 20 micrograms of inhalable particulate matter per cubic meter of air, μg/m3), developing nations, concentrated largely in South America, North Africa and regions near India and China, were in the highest ranges (between 71 to 142 μg/m3). The World Health Organization’s recommendations for pollutants are values below 20 μ/m3.

The map compares the population density in 2009 to the average annual concentration of particulate matter (PM10) throughout the world, as based on World Bank data. Credit: Fajersztajn, L., et al. Nature Reviews Cancer 13 674–678 (2013)

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“It is worth mentioning that the data are underestimated because they consider large and diverse regions. Brazil, for example, is in the same range as the United States, which has the lowest [pollution index]. However, the number is a country-wide average, which includes very polluted areas and other less polluted areas,” commented Fajersztajn.

The survey of the Web of Science database showed that research related to the impact of air pollution on health is concentrated mainly in North America and Europe, followed by China, Australia, Brazil and Japan. In contrast, such research is practically nonexistent in Africa, India and other South American countries. According to the authors, developing countries contribute only 5% of the research on the topic.

“Some could argue that some of these countries are so poor and have so many problems that that they do not have the means to produce scientific knowledge on any subject. Therefore, for comparison, we also looked at studies on malaria and water quality,” said Fajersztajn.

Of course, the United States and Europe stood out in these two fields of study. However, the results also showed that 20% of the studies on water quality and 70% of the studies on malaria were from developing countries.

The researchers stressed that in the next few years, paradoxically, the number of premature deaths caused by atmospheric pollution will tend to surpass the deaths by malaria and a lack of basic sanitation. According to the estimates of the Organization for Economic Cooperation and Development (OCDE), exposure to pollutants will be the main environmental cause of premature death by 2050.

“No one is against developing a vaccine or a new medicine for malaria, but seeking a solution to reducing pollution involves economic interests and behavioral changes, including more laws restricting automobile use. It is a considerable challenge, and science must therefore be strengthened in developing countries,” commented Fajersztajn.

 The maps indicate the distribution of particulate matter (a), articles published on atmospheric pollution (b), articles published on water quality and (c) articles published on malaria (d). The scientific production data are from the Web of Science database from March 1983 to March 2013. Credit: Fajersztajn, L., et al. Nature Reviews Cancer 13 674–678 (2013)

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Lung cancer

There is scientific evidence that correlates exposure to pollution to cardiovascular diseases, respiratory diseases, and several types of cancer. In the article published in Nature Reviews Cancer, USP researchers brought together the main studies that demonstrated how pollutants increase the risk of lung cancer.

The most recent study, published this year in The Lancet Oncology, amasses data from more than 300,000 individuals in nine countries. The results indicate that, considering lung adenocarcinoma alone, the risk of cancer in the group exposed to pollution rose 50% for each 10 µg/m3 of fine particulate material inhaled.

“Lung cancer is one of the most lethal types of cancer, and prevention has proven to be best approach to the disease. In the article, we stressed that air pollution is a risk factor for lung pollution that can be prevented, as is tobacco use,” said Fajersztajn.

Although the risk caused by pollution is not as high as that caused by tobacco (which increases the probability of developing the disease by 30 times), the researcher stressed that it remains a significant health problem because the population as a whole is exposed to certain degree.

According to Paulo Saldiva, researcher at the Laboratory of Experimental Atmospheric Pollution within USP’s School of Medicine (FMUSP) and Fajersztajn’s adviser, the pollution map shows that the regions with the worst air quality are also the most densely populated. “This means that there are many people exposed to very high levels of pollution, which is entirely related to increased cancer risk,” he said.

For Saldiva, the map also shows that the benefits of urbanization are distributed in a highly unequal manner around the world. This phenomenon, which he calls environmental racism, has major impacts on the health of the population in developing countries.

“Public policy measures are the only way to protect the population. It is the modern vaccine. There is nothing that individuals can do alone,” Saldiva stated.

For scientists, added Saldiva, the task is to produce knowledge on the risk of pollutants and to translate this information for the lay public and help raise awareness.

“One example is the case of bisphenol A or BPA (a toxin found several types of plastics that is thought to contribute to cancer, diabetes and infertility). By warning mothers of the risks of this substance, the market was able to eliminate BPA from plastic bottles. No law was needed,” he affirmed.

Saldiva coordinates the Brazilian Institute for Integrated Analysis of Environmental Risk, one of the National Institutes of Science and Technology (INCT) funded by FAPESP and CNPq in São Paulo State. He presented the results of the study during the 28th Annual Meeting of the Federation of Experimental Biology Societies (FesBE) held in Caxambu, Minas Gerais from August 21 – 24. Also collaborating in the study were researchers Mariana Veras, of FMUSP, and Ligia Vizeu Barrozo, of USP’s Geography department.