For the original article by Isabela Fraga in Portuguese published in Vozerio click here.
When talking about Zika, dengue, chikungunya and their complications, very little is discussed with regards to the models employed to combat and prevent these diseases and the vector mosquito, Aedes aegypti. Are they effective? Are they safe? In recent months, this issue came to light when rumors emerged that the microcephaly outbreak in Brazil was caused by pyriproxyfen larvicide, which is used by some Brazilian states and municipalities to combat mosquito proliferation. The Brazilian Association of Collective Health (Abrasco) has denied the relationship, but said in a technical note released last month, that they are against the use of chemicals in the fight against mosquitoes–methods such as chemical misting or spraying and diluting drinking water with larvicide.
“By waging this war against the mosquito, they are also creating a chemical war against people exposed to these poisons and the workers who apply them,” says Marcelo Firpo, a researcher at the Fiocruz Occupational Health Studies and Human Ecology Center and coordinator of Abrasco’s Health and Environment Group. In this interview, Firpo explains why he considers the current model to combat the Aedes mosquito misguided, and questions the criteria for release of substances such as malathion, classified by the World Health Organization (WHO) as “probably carcinogenic.”
1. Has the strategy adopted by governments (federal, state and municipal) against Aedes aegypti failed? Why?
We think that the current strategy has failed and is misguided. The focus should not be on the chemical fight against mosquitoes. By waging this war against the mosquito, they are also creating a chemical war against people exposed to these poisons and the workers who apply them. There are mainly two situations that we consider counterproductive to a healthy solution: the case of spraying, which uses a chemical called malathion, which the WHO’s International Agency for Research on Cancer considers “probably carcinogenic,” and diluting running water with poisonous larvicide [pyriproxyfen] that people will use for drinking, cooking, etc. We are opposed to such measures. We believe there are alternative mechanical and sanitation methods that can be applied in the short, medium and long term. Another important issue is that the people most affected are the poorest suburban populations who have more precarious living conditions and limited access to basic sanitation.
2. Can you give some examples of more effective and safer methods to prevent diseases such as Zika, dengue and chikungunya?
There are several. There are various municipalities with successful experiences. For example, specifically for locations where water is stored inside houses where poor people do not have adequate containers, there is both the ability to screen and provide appropriate covers, and even arrange smaller storage locations suitable for these families. It is worth remembering that this becomes necessary because people do not have an adequate, reliable, quality water supply. Another alternative involves mutirões, or collective efforts, so that people can get rid of different types of waste from internal and external areas of their homes. Instead of focusing on individual responsibility of families in their homes, [the government should] implement policy that employs a public health education program to address these issues definitively.
3. Meanwhile, more than 40% of Brazilians do not have access to basic sanitation. Should the focus then be on this instead of fighting the vector mosquito?
Yes, we should take advantage of this time during this health crisis to highlight the problems of urban reform, social and spatial inequality, and basic sanitation. It is worrying that at the moment, we talk about these diseases but, for example, we don’t talk about fiscal adjustments and the current crisis. In 2016, the Ministry of Health will cut its budget for the National Sanitation Plan (Plansab) and the National Health Foundation (Funasa).
4. Which chemicals used by different levels of government are the most dangerous to people? Why?
By definition, every pesticide is dangerous to health. Some are especially dangerous. For example, since March 2015 malathion has been considered probably carcinogenic. The Ministry of Health adopted this insecticide to kill adult mosquitoes by spraying in 2014. And despite the WHO’s decision, there were no modifications. The most common question to ask is: “But wasn’t the substance approved by the various regulatory agencies?” It turns out, for example, most of the accreditation criteria is based on lethal dose and experiments on animals: mice and rabbits. From this lethal dose, the researchers draw inferences of medium and long-term effects in humans. Often lethal dose experiments have a number of uncertainties regarding the medium and long term chronic effects. So it may be that only after 10, 20, 30 or 40 years, this substance is found to affect our central nervous system, cause cancers of such and such a kind… and that’s a long process, because often the problem has many causes and there is a whole complexity in establishing these correlations and these links. This can result in the effects not being seen until many years later. We believe that the use of these substances should be avoided out of precaution. Just as Abrasco stands–as far as possible–against the use of pesticide poisons in agriculture, Brazil has been the world leader in using agrotoxins since 2008.
5. Can the continued use of these chemicals generate more resistant mosquitoes?
Most likely. It is an almost inevitable cycle, well known in agriculture. After some time, the continuous application of insecticides, fungicides, etc., ends up producing resistance and, over time, these substances become more innocuous and lose effectiveness. This leads to a new chemical cycle. But often the time when you change substance is precisely when you discover the harmful effects that had not initially been seen.
6. Should the use of spraying not even be used to complement other measures combating Aedes aegypti?
In our view, these substances should be avoided at all costs. Of course there are very particular extreme cases when such methods are justified, but they are absolutely exceptional. The rule should be, don’t use poison. And, anyway, we are radically against the use of substances classified as probably carcinogenic in public spaces where pregnant women frequent.
7. In your opinion, is there some “sensationalism” in addressing the issue that ends up justifying the adoption of unsafe measures to combat the mosquito?
When there is such a complex situation, with so much uncertainty as there currently is, of course there are different approaches. And many of them are related to specific interests. It is often not easy for the public and the media to follow and clearly understand the origin of the various approaches and assumptions. This is a complex problem that must be addressed broadly. One of the problems is that many experts only analyze a particular effect. In particular, there are many epidemiological surveillance specialists focused on mosquito extermination without considering the effects of the use of poison. Our perspective is to try to overcome the narrow approach towards a broader and more holistic view. Our point is that the focus should not be to eliminate the mosquito, but the breeding grounds that allow a higher rate of infestation. In our assessment, it is the poorest women in the suburbs of the Northeast and other areas of Brazil who suffer most from this problem. It takes a comprehensive view and, without doubt, the fundamental issues are basic sanitation, access to water and socio-spatial inequality.
8. Do you think there has been a failure of control by regulatory agencies such as the Brazilian Health Surveillance Agency (Anvisa)?
We are very critical of the release methods of several pesticides. For some time, Anvisa has been moving towards a more focused approach to health protection. When it started, there was such political pressure it resulted in the departure of one of the agency’s toxicology sector coordinators, Fiocruz researcher Luiz Claudio Meirelles. There are pressures from the industrial sector and the agribusiness sector to release pesticides more flexibly and liberally on behalf of agribusiness growth.
9. Is there then a parallel, a connection between the pesticide industry and those that produce the chemicals used to combat diseases caused by vector mosquitos?
Of course. These are the same industry. I would also say that the chemical wars for confronting pests in agriculture and against mosquitoes and vectors in public health have a very similar logic. They are interested in showing that the issue is a specific problem that can be solved by the extinction of a type of species [of insect]. You may ask: why do mosquitoes proliferate so intensely? There are ecological imbalances in the formation of cities and suburbs. When you eliminate the biodiversity of a place to plant one crop or species as is the case of monocultures, for example, soybean, corn, etc., a biodiverse area becomes a sea of one single plant. And all the complexity and complementarity that ensures biodiversity for the survival of various species ends: a local organism proliferates and is considered an enemy. Chemical dependency on pesticides in modern industrial agriculture is a consequence of the destruction of agricultural systems and the difficulty of dealing in other ways with the whole ecosystem.
10. Until the 1950s, dengue was considered a benign disease, as was Zika until 2015. Is the escalation of these diseases related to the government’s approach to combat the vector?
This is a hypothesis that we point out in our technical note. It is necessary to research in this direction. For example, we consider it important to understand why certain people affected by dengue had more severe symptoms than others in other regions even though the type of dengue was the same. The same reasoning can apply to the Zika virus. Why, under certain conditions, are some symptoms more severe than others? We presented this hypothesis, for example, in a region of São Paulo where there was a clear increase in the use of chemicals [malathion] and worsening dengue symptoms. We are not claiming a direct relationship, but that it is important to investigate. After all, there is a possibility that exposure to hazardous chemicals can align with other factors in the deterioration of the immune system and certain symptoms. This needs to be further investigated.