21
Jul
Pesticide Exposure Driving Liver Disease through Hormone Disrupting Mechanisms
(Beyond Pesticides, July 21, 2022) Research published in Scientific Reports finds an association between the increasing emergence of nonalcoholic fatty liver disease (NAFLD) and exposure to endocrine (hormone) disrupting chemicals, like organochlorine pesticides (OCPs). It is well-known that traces of legacy (past-use) pesticides, like organochlorines, remain in the environment for decades—possibly centuries, post-final application, as OCPs have greater chemical stability and gradual attenuation. However, these chemicals have profound adverse impacts on human health, especially on the endocrine system. Obesity, insulin resistance, type 2 diabetes, and elevated liver enzyme resulting from endocrine disruption contribute to NAFLD and can lead to liver cirrhosis. Although some, but not all, manufacturing and use of specific OCPs have declined in the U.S., OCPs remain a global issue, as much of the developing world still reports usage. Considering the lack of studies on OCP-induced endocrine disruption and NAFLD, research like this highlights the need to understand the underlying mechanisms that contribute to growing endocrine disease incidents.
The study determined that there is an association between OCP exposure and NAFLD using the fatty liver index (FLI), a predictor of lipid (fat) accumulation in the liver. The researcher collected blood serum to measure the concentration of OCPs, specifically evaluating detectable chemicals, including DDE, oxychlordane, trans-nonachlor, and mirex. Additionally, the study investigated the relationship between liver enzymes and advanced liver fibrosis (scarring)associated with NAFLD and OCP exposure. The study finds all detectable OCPs pose a risk for NAFLD. Oxychlordane, a metabolite (breakdown product) of the OCP chlordane, is most significantly associated with NAFLD risk with the highest FLI and levels of liver enzymes, followed by trans-nonachlor, DDE, and mirex. Researchers note that OCPs are lipophilic, which dissolve into body fat and linger for several years, adversely affecting the hormonal system, metabolic function, and brain development. Thus, OCPs tend to accumulate more in individuals with higher BMIs, putting them at greater risk of NAFLD.
Pesticides are pervasive in all ecosystems, soils, water (solid and liquid), and air, frequently at levels exceeding U.S. Environmental Protection Agency (EPA) standards. Long-range atmospheric transport and condensation significantly contribute to the global contamination of environmental pollutants like OCPs. Although many OCPs are well-known persistent organic pollutants (POPs) banned by the Stockholm Convention treaty in 2001, the properties of OCPs allow these substances to remain in the environment long after use, threatening environmental and biological health. These pesticides cause various adverse effects, from respiratory issues, nervous system disorders, and birth deformities to various common and uncommon cancers. Moreover, OCPs can accumulate in regions void of industrial or agricultural activities, like glacier tops and remote territories. For instance, the U.S. banned DDT and most other highly hazardous OCPs by the late 1980s, as some pesticides exceed the EPA guidelines for human subsistence on fish and wildlife, persisting in soil and water sediments, glacier meltwater runoff, and bioconcentrate in food webs. Exposure to DDT and DDE increase the risk associated with diabetes, early onset menopause, reduced sperm count, endometriosis, and obesity. Past studies indicate DDE exposure has multigenerational health effects on obesity, diabetes, and breast cancer occurrences. Considering that 90 percent of Americans still have at least one pesticide biomarker in their body, including OCPs, advocates urge that government officials assess the ubiquitous nature of pesticides impacting all ecosystems and the health of their inhabitants for future human, animal, and environmental well-being.
This study is one of the first to use FLI to analyze the association between OCP exposure and NAFLD. The researchers suggest that FLI is a better indicator for NAFLD as diseases (e.g., hepatitis) affecting liver enzyme levels do not impact FLI analysis like traditional ALT (liver enzyme) blood tests. Oxychlordane, a metabolite of chlordane, has the highest dose-dependent associations with NAFLD prevalence of all OCPs in the study. However, researchers indicate that all OCPs induce NAFLD through oxidative, disrupting detoxification or lipid metabolism in the liver. Although organochlorine use ended in many Western nations, developing countries still encounter these chemicals through use or imports from other manufacturing nations. Current-use pesticides also contaminate the ecosystem via drift, runoff, and leaching. Nonalcoholic fatty liver disease is becoming the most prevalent form of liver disease, impacting at least 25 percent of the globe. Therefore, the impact of both current and past use of pesticides on human, animal, and environmental health, especially in combination, is critical to any safety analysis. The study concludes, “Our results showed that OCP exposure was associated with NAFLD prevalence, some of which showed a linear dose-dependent relationship. Although most pesticides have been deprecated, periodic monitoring for NAFLD appears necessary in developing countries where pesticides are still used or in areas in which pesticides have been used in the past. Further studies using in vivo experiments are needed to clarify the mechanism of the influence of OCPs on the pathogenesis of NAFLD.”
The endocrine disrupting effects of pesticides and other chemicals have extensive documentation. The World Health Organization (WHO), European Union (EU), and endocrine disruptor expert (deceased) Theo Colborn, Ph.D., classify over 55 to 177 chemical compounds as endocrine disruptors, including various household products like detergents, disinfectants, plastics, and pesticides. Endocrine disruption can lead to several health problems, including hormone-related cancer development (i.e., thyroid, breast, ovarian, prostate, testicular), reproductive dysfunction, and diabetes/obesity that can span generations. Beyond Pesticides tracks the most recent studies on pesticide exposure through our Pesticide-Induced Diseases Database (PIDD). This database supports the clear need for strategic action to shift from pesticide dependency. For more information on the multiple harms that pesticides can cause, see PIDD pages on Endocrine Disruption and other diseases.
One way to reduce human and environmental contamination from pesticides is to buy, grow, and support organic. Numerous studies find that levels of pesticides in urine significantly drop when switching to an all-organic diet. Furthermore, given the wide availability of non-pesticidal alternative strategies, families, from rural to urban, can apply these methods to promote a safe and healthy environment, especially among chemically vulnerable individuals or those with health conditions. For more information on why organic is the right choice for consumers and the farmworkers that grow our food, see the Beyond Pesticides webpage, Health Benefits of Organic Agriculture.
All unattributed positions and opinions in this piece are those of Beyond Pesticides.
Source: Scientific Reports
