Scientists Investigate the Effects of Pesticides on Thyroid Cancer

Ten of the 29 pesticides examined by experts, including some of the most commonly used in the United States, were connected to thyroid cancer in single pollutant models over a 20-year period.

These included oxyfluorfen, glyphosate, and paraquat dichloride.

Additionally, 20 years before diagnosis or the study interview, the risk of thyroid cancer increased according to the total amount of pesticides to which patients were exposed.

Paraquat dichloride was linked to thyroid cancer in every animal.

Relationship of Pesticides to thyroid cancer

(Photo : Arjun MJ/Unsplash)

According to the authors, this study offered the first proof in favor of the theory that residential pesticide exposure from agricultural use increases the risk of thyroid cancer.

Incidence of thyroid cancer has increased significantly in the United States during the past 30 years, growing approximately 3% yearly.

While some experts blame the rise on improved detection techniques, other publications contend that environmental, genetic, and lifestyle risk factors may also be to blame.

Except for studies concentrating on radiation exposure, few studies have looked at the impact of environmental exposures on thyroid cancer incidence.

According to earlier research, there are greater hazards for people who work in the leather, wood, and paper industries as well as those who are exposed to pesticides, flame retardants, and environmental solvents.

Certain pesticides have been proven to be known mutagens or to cause tumor growth and chromosomal abnormalities in cultured cells.

These include 19 pesticides that cause DNA cell damage in vitro including the active ingredient in popular herbicides, glyphosate.

Pesticides can also change how thyroid hormones are produced, which has been linked to a higher risk of developing thyroid cancer.

Previous research on the relationship between pesticides and thyroid cancer has been inconsistent or had methodological flaws, such as self-reporting of exposures, a lack of details on particular pesticides, and small sample numbers.

California produces the most agricultural output of any state in the United States.

In addition, California used 162 million pounds of agricultural pesticides in 2008 or nearly 25% of the total amount used in the United States.

Advanced thyroid cancer cases have been rising in the state in the meantime.

This study looks at the relationship between thyroid cancer risk and exposure to pesticides, including 19 that were found to damage DNA cells.

The researchers proposed that pesticide exposure might be a crucial missing piece that needs more research.

Using thyroid cancer cases from the California Cancer Registry (1999-2012) and controls drawn from a population-based sample, the authors conducted a case-controlled analysis.

Participants in the trial were 35 years of age or older, thyroid cancer patients, and residents of the study area at the time of their diagnosis.

Those who were 35 years of age or older and had resided in California for at least five years prior to the research interview were eligible to be recruited as controls from the same geographic area.

2067 thyroid cancer cases and 1003 control participants made up the study sample.

Also Read: Common Pesticide Inhibits Bumblebees From Collecting Pollen

Pesticides and cancer

American research According to the National Institutes of Health (NIH), thyroid cancer risk is increased by exposure to the insecticides lindane and metalaxyl, as per Beyond Pesticides.

Thyroid cancer in its advanced stages and cases of non-aggressive thyroid tumors are both on the rise.

However, given how commonplace pesticide exposure is among the general population, experts hypothesize that environmental contaminants like pesticides may be part of this rise.

Over 8 million people die from cancer each year, making it one of the top causes of mortality worldwide.

In particular, the International Agency for Cancer Research (IARC) anticipates a 67.4% increase in new cancer cases by 2030.

There are more cases of thyroid and reproductive malignancies as a result of endocrine (hormone) disruption caused by various environmental contaminants like pesticides.

Therefore, research like this emphasizes how crucial it is to comprehend how pesticide use might raise the risk of latent diseases (like cancer), which do not manifest themselves immediately after exposure.

"More work is needed to understand the potential function of these compounds in thyroid carcinogenesis," the researchers wrote.

The Agricultural Health Study, a cohort of certified pesticide applicators between 1993 and 1997 and 1999 to 2005, provided data on pesticide use and exposure.

50 different pesticides are included in exposure records, and for 44 of them, researchers looked at the risk of thyroid cancer.

The cumulative intensity-weighted lifetime exposure method was used by scientists to identify the factors that affect exposure expressed in days.

The incidence of thyroid cancer among male participants was evaluated by researchers in 2014 to 2015, and they used Cox regression to calculate hazard ratios and confidence intervals.

According to the study, individuals' exposure to the insecticides lindane and the benzenoid fungicide metalaxyl raises their risk of developing thyroid cancer.

Thyroid cancer showed an inverse relationship with high levels of carbaryl (a carbamate pesticide).

Additionally, papillary cancer, a frequent thyroid cancer subtype, and chlorimuron-ethyl (herbicide), have an antagonistic relationship.