Exposure to All Pesticide Classes Increase Nervous System Tumor Risk

(Beyond Pesticides, September 21, 2023) A literature review published in Ciência & Saúde Coletiva finds environmental exposure to all classes of pesticides (fungicides, herbicides, insecticides) has an association with childhood astrocytoma (brain/central nervous system [CNS] tumor). CNS tumors represent half of all malignant neoplasms (tumors) in children. Although medical advancements in disease survival are progressing, childhood cancer remains the leading cause of death from disease among children. Furthermore, childhood cancer survivors can suffer from chronic or long-term health complications that may be life-threatening. The etiology or cause of childhood cancer involves the interaction of multiple components that include environment, lifestyle and genetics. However, emerging evidence indicates that environmental contaminants like pesticides (e.g., occupational exposures, air pollution, pesticides, solvents, diet, etc.) affect disease etiology.

Pesticide contamination is widespread in all ecosystems, and chemical compounds can accumulate in human tissues, resulting in chronic health effects. Children are particularly vulnerable to the impacts of pesticide exposure, as their developing bodies cannot adequately combat exposure effects. Moreover, several studies demonstrate an association between environmental or occupational pesticide exposure and the risk of childhood cancer. Considering that maternal pesticide exposure can have a stronger association with cancer among children than childhood exposure, and newborns can still encounter pesticides, it is essential to understand how pesticide accumulation and co-occurrence can increase the risk of latent diseases (e.g., cancers) among vulnerable populations, such as children/infants.

In this piece, Brazilian researchers systematically review the literature in the PubMed/MEDLINE, Embase, Web of Science, Scopus, and CINAHL databases to investigate the association between pesticide exposure and CNS tumors in children aged 0 to 14. The literature review identifies 1,158 studies associated with CNS and pesticide exposure, with the paper focusing on 14 eligible studies. The results confirm evidence of CNS tumor development, specifically brain tumor development, among children exposed to all classes of pesticides. The most common exposure setting was in the home.

There is a significant scientific connection between pesticides and cancer, as several studies link pesticide use and residues to various cancers. Both current and past-use pesticides and chemical contaminants play a role in similar disease outcomes as several chemicals have implications for specific cancer risks (e.g.,  breast cancer, non-Hodgkin’s lymphoma, prostate cancer, etc.). Additionally, 66 percent of all cancers have links to environmental factors, especially in occupations of high chemical use. In addition to the robust links between agricultural practices and pesticide-related illnesses, over 65 percent of commonly used lawn pesticides and 70 percent of commonly used school pesticides have links to cancer. Although general pesticide exposure can increase susceptibility to cancer, prenatal and early-life exposure to environmental toxicants can increase cancer risk. For decades, studies have demonstrated that childhood and in-utero exposure to the U.S.-banned insecticide DDT increases the risk of developing breast cancer later in life. Moreover, a 2021 study finds previous maternal exposure to the chemical compound during pregnancy increases the risk of breast cancer and cardiometabolic disorders (e.g., heart disease, obesity, diabetes) up to three successive generations. 

This study highlights that any pesticide type can lead to CNS tumor development. Most notably, exposure to pesticides in the home represents the most typical type of exposure setting. This is concerning as most of one’s lifetime is spent in the home. This study is not the first to find a risk between childhood cancer development and household pesticide exposure. Pregnant mothers’ exposure to household cleaners, many of which are pesticides, can increase nephroblastoma (kidney cancer) and brain tumor risk in children. Therefore, it is essential to understand how external stimuli—like environmentally relevant pesticide exposure—can drive cancer development to avoid exposure and lessen potential cancer risks. The study concludes, “The investigation of factors related to the risks of using pesticides is vital to inform environmental policy and curb the indiscriminate use of these substances in agriculture. […] A package of measures are therefore required, including public policies, effective environmental protection, and educational initiatives in primary health care services. The latter should address the residential use of potentially harmful chemicals, encourage healthy eating based on the consumption of organic foods, promote the use of personal protective equipment by parents employed in agriculture, and provide guidance to avoid the use of pesticides in the home before and during pregnancy.”

Globally, cancer is one of the leading causes of death, with over eight million people succumbing to the disease every year. Notably, the International Agency for Cancer Research (IARC) predicts a 67.4 percent rise in new cancer cases by 2030. Thus, it is critical that both government officials and the public understand the health implications of pesticide use and exposure on humans, especially when pesticides increase chronic disease risk. Beyond Pesticides tracks the most recent news and studies on pesticides through the Daily News Blog and Pesticide-Induced Diseases Database (PIDD). This database supports the need for strategic action to shift away from pesticide dependency. For more information on the adverse effects of pesticides on human health, see PIDD pages on cancer (lymphoma, multiple myeloma), birth/fetal defects, and other diseases. Additionally, since pesticides can have multi-generation impacts on our health, you can learn more about the hazards posed to children’s health through Beyond Pesticide’s Pesticide and You Journal article, “Children and Pesticides Don’t Mix.”

There is a strong consensus among pediatricians that pregnant mothers and young children should avoid pesticide exposure during critical windows of development. However, the general population should follow this advice as the effects of pesticide exposure span every individual. Fortunately, the wide availability of non-pesticidal alternative strategies allows families and agricultural industry workers to apply these methods to promote a safe and healthy environment, especially among chemically vulnerable individuals. For instance, buying, growing, and supporting organic land management can reduce human and environmental contamination from pesticides. Organic agriculture has many health and environmental benefits, which curtail the need for chemical-intensive agricultural practices. Numerous studies find that pesticide metabolite levels in urine significantly decrease when switching to an all-organic diet. For more information on how organic is the right choice for both consumers and the farmworkers that grow our food, see the Beyond Pesticides webpage on Health Benefits of Organic Agriculture.

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

Source: Ciência & Saúde Coletiva