- Recent research has revealed human contamination by pesticides in the Brazilian Cerrado, following a previous study that also found contamination in tapirs in the region.
- This research shows how animals are providing information and inspiration for research with humans, while emphasizing that the stress endured by South America’s largest terrestrial mammal is also evidenced in people.
- Despite inspiring research on human health, tapirs themselves are not free from the challenges to their survival imposed by human actions; the species is classified as threatened by the IUCN Red List and qualified as vulnerable to extinction.
- The former president of the Brazilian federal environmental protection agency, IBAMA, says the approval of a bill that made the use of pesticides more flexible in Brazil could worsen situations like those reported by the researchers.
It was in 2015 when researchers were attempting to capture tapirs (Tapirus terrestris) in the Brazilian Cerrado to install monitoring collars so they could study the species. While trying to complete the anesthetic procedure, they noticed that the anesthesia was not working, and as a result, they had to supplement the doses for the procedure to take effect.
This was the catalyst for research that revealed years later that tapirs in the region were contaminated with various types of pesticides and had alterations in organs important for metabolism. At the time, researchers hypothesized that something in the tapirs’ bodies was interfering with the anesthesia. One possibility was pesticide exposure, which is linked to changes in the metabolic process. Now, another hypothesis raised by the researchers back then has recently been confirmed: Residents of the same region also show contamination by pesticides.
The tapir findings prompted researchers to collect biological samples from roughly 100 nearby residents, and more than 30 people tested positive for some form of pesticide, with more than one chemical present in some cases. The most widely used pesticide in Brazil, glyphosate, was found in more than 20 people.
The work, released in a technical report in February, was conducted by researchers from the National Initiative for the Brazilian Tapir Conservation (INCAB) of the Institute of Ecological Research (IPÊ), who are preparing a paper on the research for publication in a scientific journal.
This research shows how animals are providing information and inspiration for studies with humans, which is another example of the importance of animals for the planet and for people. The findings emphasize that the stress endured by South America’s largest terrestrial mammal is also evidenced in humans.
Potential links: Pesticides & organ damage
Patrícia Medici, co-founder of IPÊ, coordinator of the INCAB, and one of the world’s leading tapir specialists, tells Mongabay in a video call that the required dosage of anesthesia for an animal depends on its metabolism rate. She emphasizes the importance of organs such as the liver and kidneys in this process, stating, “If these organs are damaged, metabolism occurs differently, which necessitates a different approach to anesthesia.”
Regarding the tapirs captured by INCAB in the Cerrado, Medici notes that “larger quantities of anesthetic agents were necessary,” leading to the hypothesis that these animals might have alterations in these organs, possibly due to pesticide contamination.
In a study spanning 2015-17, which involved the necropsies of tapirs killed in road accidents in the region, the INCAB researchers found evidence that helps confirm the suspicion. “What we found the most were liver injuries, kidney injuries and also stomach injuries,” the researcher says.
The work, later published in the journal Wildlife Research, documented the contamination of the tested animals by various types of pesticides, such as insecticides and herbicides, as well as metals.
Medici acknowledges that although the evidence implies a connection, it is yet not possible to assert that the injuries found had resulted from pesticide contamination. Therefore, further investigations are needed, she says. “The context leads us to believe they are related, but we haven’t conducted necropsies in other biomes to compare samples,” she says. “Only by comparing with a control sample could we assert with certainty.”
Human contamination
The recent INCAB research on humans was carried out in a 2,200-square-kilometer (849-square-mile) area, the same area where the tapir study was conducted, in the municipalities of Nova Alvorada do Sul and Nova Andradina, in Mato Grosso do Sul state, west-central Brazil. Medici characterizes the area as a “diverse mosaic,” encompassing various land uses, from eucalyptus plantations and highways to large agribusiness farms, with sugar cane being a predominant crop, as well as agrarian reform settlements where small-scale family farming is practiced.
Over a week-long period in 2023, the researchers collected biological samples, such as blood and urine, from 94 residents, mainly small-scale rural producers involved in agriculture and cattle ranching, ranging in age from 19 to 73, in areas close to where tapirs contaminated by pesticides had been found years earlier. Study participants also underwent a consultation and were interviewed to identify potential previous or current contacts with pesticides.
The research found that 36 of the sampled individuals were contaminated with residues of some type of toxic products, with the detection of five different pesticides, including glyphosate and malathion, which the INCAB researchers consider to be the main pesticides detected.
Specifically, it was found that 25 individuals, or 32%, out of the 78 sampled for glyphosate in urine samples were contaminated by the pesticide with “dosage values above the expected,” says the INCAB report, meaning higher than 0,6 μg/l. Among these, some showed cross-contamination, such as glyphosate-malathion.
The research further revealed heavy metal contamination in 22 out of the 94 individuals sampled, with 18 testing positive for mercury and four for copper. The latter exhibited concentrations exceeding the maximum expected limit, as stated by INCAB. “The normal range for copper levels in human blood can vary between 60 and 140 ug/dL,” the researchers say in a press release, citing references from CIATOX, a laboratory of the Institute of Biosciences at São Paulo State University. “One individual tested positive for copper at a level of 223 ug/dL,” they add.
The INCAB report states that the scientific literature lacks information on the effect of what they call an “agrochemical cocktail,” or the potential synergy between pesticides and metals, but says there is evidence that in cases of mixed intoxication, the effects can be exacerbated.
Origin of human contamination
“Both the wild animal and the human being are exposed, are being intoxicated,” medical doctor Maurício Antônio Pompilio, who has a Ph.D. in infectious diseases and is a professor at the School of Medicine of the Federal University of Mato Grosso do Sul (UFMS), tells Mongabay in the video call in which Medici also took part, confirming the hypothesis raised during the initial study that detected pesticides in the Cerrado tapirs.
As a member of the multidisciplinary research team that authored the newly published INCAB report, he says human contamination may have occurred both individually, during agricultural work without the proper use of personal protective equipment, and collectively, influenced by large-scale crops such as sugar cane and soybeans. He notes that this is mainly observed through reports from the sampled population that they have “indeed seen … aircraft spraying in nearby areas.”
The research indicates that more than one-third of the sampled individuals reported living or working in areas close to pesticide application areas, and that, notably, 30% reported witnessing aerial pesticide spraying. “Of these, 21% claimed to be in the vicinity of the sprayed area at the time of application,” the INCAB report notes.
Pompílio highlights that pesticide contamination can affect the liver, kidneys and gastrointestinal tract, causing symptoms such as nausea, vomiting and diarrhea. “Not to mention, for example, skin and eye irritation.”
He says the nervous system and muscular motor function also suffer significantly, potentially leading to severe consequences, including coma or death. The researcher also emphasizes that some pesticides may “facilitate cancer development in the body.”
A prime example is glyphosate, which the World Health Organization’s International Agency for Research on Cancer categorizes as possibly carcinogenic to humans. Glyphosate is the primary ingredient of Roundup, a product previously manufactured by Monsanto. The now-defunct company is embroiled in numerous lawsuits alleging that its weed killer is responsible for causing cancer.
A sentinel species
The recent research from INCAB exemplifies how humans are not separate from the environment and, consequently, from the impact of their advancement on natural areas. In a shared landscape, research on one species can lead to findings about another. In this case, aspects of human health were revealed following aspects of tapir health, a large, long-lived and wide-ranging herbivore, which feeds on a wide variety of plants, seeds and fruits.
Medici, the IPÊ co-founder, says the species consumes 7-10 kilograms (15-22 pounds) of fruits per day. She notes that tapirs cover vast distances, sometimes spanning up to 10 kilometers (6.2 miles) in a single night of foraging. “While now she is here in the forest, soon she will be crossing a sugar cane plantation.”
This behavior makes tapirs crucial seed dispersers, as the seeds they ingest are transported over great distances. “In doing so, she’s playing with the diversity, with the biodiversity of these areas where she is found,” the researcher explains.
She says a forest where tapirs are present differs completely from one where they might eventually become extinct. “They maintain the integrity of the forest’s diversity and the habitat where they are found.”
The species serves as an indicator of its surrounding environment and acts as a sentinel species, moving through various landscapes along its journeys. What the tapir experiences, so, too, do other species — including humans. “The tapir is the thermometer itself,” Medici adds.
Inspiring, but increasingly threatened
Despite inspiring studies on people, the sentinel tapirs are not free from the challenges to their survival imposed by human actions. Classified as threatened both by the IUCN Red List and by the Brazilian list of endangered species, the species is qualified as vulnerable to extinction.
In the Brazilian Cerrado, for instance, where it is classified as endangered, the species faces numerous threats, including hunting for meat and other purposes; habitat loss due to the conversion of natural landscapes for cattle ranching and cultivation of crops like soybeans, sugar cane and corn; wildfires; roadkill; and, as shown by INCAB, contamination by pesticides.
Medici explains that despite the challenge of accurately determining the impact of pesticide exposure on tapirs, the reality for the species in the Cerrado is compromised health. “Determining what percentage of this is attributable to pesticides? We’ll need a few more years to definitively answer that question.”
Research already suggests that the animal in the Cerrado is less healthy than in the Atlantic Forest and the Pantanal. The researcher says that this declining health leads tapirs to die at a younger age and reproduce less often. “While in the Pantanal we have observed some reproductive adult females as old as 26 or 27 years old, indicating a significantly longer lifespan with consistent reproduction, in the Cerrado, we haven’t observed any tapir older than 16 years old.”
According to the collaborative mapping platform MapBiomas, by 2022, half of the Cerrado had already been significantly altered by human activities, compared with only about 15% in the Pantanal. This scenario poses challenges to the survival of T. terrestris, such as habitat fragmentation.
Medici explains that in an environment with established populations, this fragmentation results in their disconnection from one another.
The researcher emphasizes that in the INCAB research area, located in the Cerrado savanna region of Mato Grosso do Sul state, there are no established populations due to insufficient habitat for “de facto populations.” She describes the area as a landscape already shaped by habitat loss, where only about “20% to 25% is actually remaining habitat for the animal.”
She recalls that during the previous tapir study, the region was undergoing a transition from cattle ranching to soybean cultivation. “Many producers in the region were undergoing this transition process and continue to do so to this day. This is a phenomenon that we have seen across Brazil.”
The researcher underscores the difficult situation of tapirs in the region, stating, “We often say that what we have there in the Cerrado are individuals roaming through that landscape, seeking ways to survive.”
The deregulation of pesticide use
Brazil is the world leader in pesticide use, according to 2021 FAO data. That year, the country used more than 719,000 tons of pesticides, with the United States closely following, using more than 457,000 tons.
Suely Araújo, former president of the Brazilian federal environmental protection agency, or IBAMA, tells Mongabay in a phone interview that Brazil excessively uses pesticides and argues that there should be stricter control over their usage, as well as their effects on wildlife. “The issue is that the legislation has become more flexible instead of stricter,” she says, referring to the approval, in late 2023, of a bill that allowed for more flexibility in the use of pesticides throughout the country.
The so-called “Poison Bill,” a priority project of the ruralist caucus, eases restrictions on the sale and use of a wide range of agrochemicals, many of which can cause diseases, mutations and hormonal changes. It also relegates the approval of new pesticides to a risk analysis, and experts such as Araújo say they have no knowledge of how it will be carried out.
The bill was enacted into law by President Luiz Inácio Lula da Silva earlier this year, with vetoes that, although important, do not solve the problem, says Araújo, who is currently a senior public policy adviser at the civil society coalition Climate Observatory. “It’s a law that should not have been approved,” she says. “The law still has a serious problem from the standpoint of public health and the environment.”
“What is allowed for glyphosate in our drinking water is 5,000 times higher than what people in Europe have in the water they drink,” adds Medici, arguing laboratories analyzing food and water employ high and flexible reference parameters. “Even putting a number and proving that what is present is not adequate is difficult here in our country.”
The researcher contends that there should be a serious discussion regarding safe levels of pesticide exposure in Brazil, as well as the detection thresholds for these substances in water and food consumed domestically. “This discussion is urgent; it’s for yesterday, it needs to happen.”
Araújo, who says the approval of the Poison Bill can worsen situations like those reported by INCAB studies, is emphatic. “We’re talking about the right to life of animals but also of people.”
Mongabay reached out to the Brazilian Ministry of Agriculture, seeking comments on the recent INCAB technical report and its recommendations for enhanced monitoring of pesticide use and trade, as well as measures to mitigate environmental contamination by pesticides and metals. The ministry did not provide comments and instead directed Mongabay to contact IBAMA. Neither IBAMA nor the Brazilian Ministry of Health, which was also contacted, responded to Mongabay.
Banner image: A tapir amid a harvested cornfield in northern Mato Grosso, west-central Brazil, in a transition area between the Cerrado and the Amazon. Image by Victor Sanches, courtesy of INCAB/IPÊ.
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Citations:
He, B., Ni, Y., Jin, Y., & Fu, Z. (2020). Pesticides-induced energy metabolic disorders. Science of The Total Environment, 729, 139033. doi:10.1016/j.scitotenv.2020.139033
Medici, E. P., Fernandes-Santos, R. C., Testa-José, C., Godinho, A. F., & Brand, A. (2021). Lowland tapir exposure to pesticides and metals in the Brazilian Cerrado. Wildlife Research, 48(5), 393-403. doi:10.1071/wr19183
Singh, N., Gupta, V. K., Kumar, A., & Sharma, B. (2017). Synergistic effects of heavy metals and pesticides in living systems. Frontiers in Chemistry, 5. doi:10.3389/fchem.2017.00070
Fernandes-Santos, R. C., Medici, E. P., Testa-José, C., & Micheletti, T. (2020). Health assessment of wild lowland tapirs (Tapirus terrestris) in the highly threatened cerrado biome, Brazil. Journal of Wildlife Diseases, 56(1), 34. doi:10.7589/2018-10-244