Soybean Production and Pesticides Linked to Childhood Leukemia Deaths in Brazil

Brazil’s booming soybean sector has a deadly cost, according to a new study published in Environmental Sciences.

The high quantities of pesticides used on the crops are thought to be responsible for the country's rising rates of childhood cancers.

After analyzing a wide range of data, including soybean hectarage, water contamination levels and hospital records, the researchers found a statistically significant increase in pediatric leukemia cases following expanded local soy production.

They say that this link to childhood cancers is “only the tip of the iceberg” and many more health issues in Brazil are likely linked to soybean pesticide exposure.

The soy from Brazil

Brazil is the world’s largest producer of soybeans. In the past decade, millions of hectares of former cattle farmland have been converted into soybean fields. The bulk of this produce is then exported to China to form the basis of many food products, from doenjang to tofu. 

This intense agriculture is matched with intense levels of pesticides. On average, Brazilian farmers apply pesticides (per hectare) at a rate 2.3 times higher than those in the US and 3 times higher than those in China. Many of these pesticides then leach out into nearby rivers.

According to Pesticide Action Network UK, long-term exposure to pesticides has been linked to the development of Parkinson’s disease, asthma, depression and anxiety, ADHD and cancer, including leukemia and non-Hodgkin’s lymphoma.

After taking a closer look at the country’s waterways and leukemia cases from nearby hospitals, the researchers – from the universities of Illinois, Denver and Wisconsin-Madison – found that a 10% increase in soy production in an upstream area preceded on average an additional 2.70 deaths of children under the age of 5 per 10,000 population and an additional 1.38 deaths under the age of 10 per 10,000 population.

Most of these deaths could be mitigated by high-quality healthcare, according to the researchers, as acute lymphoblastic leukemia is quite treatable in children, if addressed early enough.

However, many of the regions with high soy production are rural and lack high-quality healthcare infrastructure. Therefore, many childhood leukemia cases in these Amazon and Cerrado regions, say the researchers, will have gone untreated for too long.

In total, the researchers estimate that Brazilian soy production can be linked to 123 additional deaths of children under the age of 10 between 2008 and 2019. This is roughly half of all reported deaths in Brazil from acute lymphoblastic leukemia of children under 10 in the same period.

The research team says they ruled out other potential causes for these deaths by conducting a placebo test to measure if soy expansion affected pediatric deaths from slips, trips and falls. It didn’t. They also performed a data test to see if other crops, like pineapple and sorghum – which are normally sprayed with fewer pesticides – could be linked to the rise in leukemia deaths. Once more, the researchers couldn’t make a connection.

Soybean pesticides are the cause behind the leukemia deaths, they conclude, and the damage from the chemicals likely doesn’t stop there.

“It is likely that pesticide exposure impacts many other forms of illness that we do not study here, including other forms of cancer, neurological illnesses and acute pesticide poisoning,” the researchers write in their paper.

Reference: Skidmore ME, Sims KM, Gibbs, HK. Agricultural intensification and childhood cancer in Brazil. Environ. Sci. 2023;120(45):e2306003120. doi: 10.1073/pnas.2306003120