Endocrine Disruptors and Thyroid Health: Part 1
Published October 21 2013
Endocrine disrupting chemicals (EDC) are compounds which have a negative impact on the endocrine system. There are many different chemicals which have the ability to disrupt the endocrine system. In this article I’ll be focusing on pesticides, as these chemicals have been proven to have a negative effect on thyroid health.
How do endocrine disruptors cause harm? EDCs can act on the estrogen, androgen, and thyroid hormone receptors (1), and they can bind to and activate various hormone receptors and then mimic the natural hormone’s action (1). This antagonist action blocks the receptors and inhibits their action (1). Finally, EDCs may also interfere with the synthesis, transport, metabolism and elimination of hormones, thereby decreasing the concentration of natural hormones (2). There are many different types of endocrine disruptors, but in this article I’ll be focusing on the impact that pesticides have on our endocrine system.
Don’t Think You’re Being Exposed To Pesticides…Think Again!
Pesticides are of course used to eradicate certain organisms. They are used in crops, the food we eat, inside and outside of homes and in different businesses, and numerous other places. As a result, pesticides are widespread, as they are in the food, in the water, and in the air we breathe. And so even if you don’t use pesticides in your own home and eat a 100% organic diet, you are still being exposed to pesticides. When you go to a restaurant, movie theater, or many other businesses you will be exposed to the pesticides they use. If you work in a corporate environment then there is also a chance that pesticides are being used.
In fact, many years ago when I opened my very first practice I had an insect problem, and I hired an exterminator. And while they claimed to use more natural and “safe” products, who really knows for certain? I know better now, but most other businesses don’t know nor care about the negative impact that these chemicals can have on their employees and customers.
Can Organic Food Have Pesticides?
With regards to organic food, unfortunately eating organic food doesn’t always mean you are avoiding pesticides. There have been incidences when some organic produce was found to have pesticides. However, in most cases, eating organic food is a safer bet than non organic food. Recently there was a review of certain studies which compared the health effects of organic and conventional foods (3). According to this, two studies reported significantly lower urinary pesticide levels among children consuming organic versus conventional diets. Even though there might still be risks of pesticide exposure when consuming organic food, if you minimize your exposure to pesticides yet don’t completely eliminate them it would still be worth eating organic in my opinion.
Since the discovery of DDT in 1939, numerous pesticides (organochlorides, organophosphates, carbamates) have been developed and used extensively worldwide with few guidelines or restrictions (4). In 1992 the World Health Organization (WHO) reported that roughly three million pesticide poisonings occurred annually, resulting in 220,000 deaths worldwide. And over the last few decades since this was reported, things have only gotten worse.
To no surprise farmers seem to be at high risk to the effects of endocrine disruptors, as they are exposed to a greater amount of pesticides than the general public. Some studies have shown that the incidence of hormone-related organ cancers, or hormonal cancers, is elevated among farmers (5). In humans, pesticides have been classified as carcinogens by the International Agency for Research on Cancer (6). So while the focus of this article is on the impact that these chemicals have on the endocrine system, they can lead to other health issues as well.
Among the organochlorine pesticides tested, toxaphene, dieldrin, and endosulfan had estrogenic properties comparable to those of DDT and chlordecone (7). There are several environmental chemicals capable of binding to the androgen receptor and interfering with its normal function, including the organophosphate pesticide fenitrothion (8).
Pesticides and Thyroid Health
One study examined the association between the use of organochlorines and risk of hypothyroidism and hyperthyroidism (9). They found that the use of chlordane, the fungicides benomyl and maneb/mancozeb, and the herbicide paraquat was significantly associated with hypothyroidism. Maneb/mancozeb was the only pesticide associated with both hyperthyroidism and hypothyroidism. That data in the study showed that there was a role of organochlorines and fungicides in the etiology of thyroid disease. Another study investigated the effects of chronic exposure to organochlorine pesticides on thyroid hormone levels in children (10), and the data showed that exposure of children to organochlorine pesticides produced a significant increase in serum total T3 concentrations.
Another study looked to assess the burden of organochlorine pesticides and their influence on thyroid function in women (11). Out of the analyzed pesticides, the concentration of p,p’-DDT and its metabolites was higher in all the subjects, but dieldrin was found to be significantly high in the hypothyroid women.
Yet another study evaluated the pesticide effects on reproductive and thyroid hormones of cotton farmers (12). The study concluded that pesticide exposure is associated with thyroid and reproductive hormone level disturbance. There is also evidence that pesticides, along with other environmental factors, can also be a factor in thyroid autoimmunity (13) (14).
The paraoxonase-1 enzyme (PON1) plays an important role in the toxicity of some organophosphate pesticides, with low PON1 activity being associated with higher pesticide activity (15). One study looked at the interaction between exposure to organophosphate compounds and PON1 enzyme activity on serum levels of TSH and thyroid hormones in a population of workers occupationally exposed to pesticides (15). The results of the study suggest a strong association between organophosphate pesticides and thyroid function in individuals with lower PON1 activity.
How Can You Minimize Your Exposure To Pesticides?
Although you won’t be able to completely avoid exposure to pesticides, here are a few things you can do to minimize your exposure to these chemicals:
1. Eat as many organic foods as possible. Although eating organic might not completely eliminate the pesticides, it will without question reduce your exposure to these chemicals. You might even want to consider growing your own fruits and vegetables. Also, it’s a good idea to be aware of those fruits and vegetables which have a greater amount of pesticides. You can find out this information by visiting http://www.ewg.org/.
2. Wash your produce. Even if you buy all organic fruits and vegetables, it still is a good idea to wash all fruits and vegetables before eating them. I would recommend using a fruit or vegetable wash which is designed to help remove pesticides.
3. Use safe insect repellents whenever possible. If you have a bug problem then try to first use more natural insect repellents before calling an exterminator. I realize there might be times when an exterminator is necessary, but many times this isn’t the case. There are exterminators which claim to use eco-friendly non toxic natural pest control, and so if you absolutely need to hire an exterminator you can try to find someone who will use less toxic products.
Find out the pest control policy of your place of work, as well as your child’s school. If your place of work and/or child’s school uses pesticides, then see if they are part of the Integrated Pest Management, which can be used to solve pest problems while minimizing risks to people and the environment (16).
4. Have everyone remove their shoes when in your house. This not only will help prevent people from spreading pesticides throughout your house, but other toxins as well. Don’t be afraid to ask your guests to remove their shoes as well.
In summary, there is no question that exposure to pesticides can disrupt the endocrine system. Of course everyone is exposed to pesticides, but not everyone has an endocrine condition. And I think it’s safe to say that most people who have an endocrine condition didn’t develop it due to pesticide exposure. With that being said, since pesticides not only can affect the receptors of some of the hormones, as well as potentially trigger an autoimmune response, one wants to do everything possible to minimize their exposure to pesticides.