The Health Impacts of Chemical Fertilizers

by Bashar Khiatah, MDNutrition
Hand-picked root vegetables

The conventional food industry throws huge money toward self funded research that supports their agenda. They also block research that investigates the impact of conventionally grown produce on the environment and on living species, as well as on the nutritional superiority of organic food, making it challenging for the consumer to gain a complete understanding of the literature. We were able to dig deeper in the ocean of research to look for studies on fertilizers that were not funded by the conventional food industry.

Organic Farming

Organic farming is a specific production system that avoids the use of synthetic and harmful pesticides, fertilizers, growth regulators, and livestock feed additives. Organic produce is that which has been farmed this way. Much confusion surrounds the term organic. There are different types of organic food labels, which are delineated on the USDA website (1). In order for a product to be labeled as ‘organic’, 95 percent of a product's ingredients must be organic. While if 100 percent of the ingredients are organic, the product can be labeled ‘100 percent organic’. Another kind of label says 'made with organic ingredients' and that’s when at least 70 percent of the ingredients are organic.

The Environmental Impact of Chemical Fertilizers

In previous blog posts, we have reported about the detrimental effects of pesticides, such as glyphosate and atrazine. Here we will look into fertilizers. A fertilizer is a natural or synthetic substance that is applied to soils to supply one or more nutrients essential to the growth of plants (2). They contain main plant macronutrients like nitrogen, phosphorus, potassium. They also contain secondary plant macronutrients calcium, magnesium, and sulfur and micronutrients like copper, iron, manganese, molybdenum, zinc, and boron (3). In general, fertilizers can be categorized as organic fertilizers and chemical (or inorganic) fertilizers. Organic fertilizers are not used commercially due to lower productivity. These fertilizers break down in nature, making them less effective for commercial purposes, but far more eco-friendly (4). Instead, conventional agriculture uses chemical fertilizers, which provide far greater yield. However, these chemical fertilizers have a widespread detrimental impact on our ecosystem. One of these impacts is eutrophication or hypertrophication of fresh water, meaning that bodies of fresh water become heavily enriched with minerals and nutrients due to runoff from land. This results in a number of downstream effects. Eutrophication induces excessive growth of water plants and algae which can kill off marine animals, as well as cause overgrowth of Cyanobacteria which can produce harmful toxins that can accumulate in the food chain and can be harmful to humans (5). Phosphate is the main contributor to the eutrophication effect, which adheres tightly to the soil and is transported to the freshwater through erosion (6). Additionally, the chemical fertilizers that have polluted the rivers, lakes, and even oceans are high in nitrogen-rich compounds which cause oxygen depletion (7). It doesn’t take much of an imagination to anticipate what happens to life under the water when oxygen is depleted.

It has been reported that the chemicals found in chemical fertilizers, specifically nitrate, are the main contributors to water pollution in general (8). The effects of chemical fertilizers on soil include: acidification, which limits the nutrient bioavailability (9), accumulation of toxic elements like, cadmium, fluoride, radioactive elements, lead, arsenic, chromium, and nickel (10-13), and finally disruption of the biology of the soil.

The Human Impact of Chemical Fertilizers

In regards to human health, the effects of chemical fertilizers are serious, both with their direct toxic effect, or in the indirect effects that are related to decreasing the nutrient density in the consumed plants. A study conducted at Warren Alpert Medical School of Brown University reported a substantial role of nitrosamine exposure in Alzheimer's disease, diabetes mellitus, and non-alcoholic steatohepatitis (14). This exposure comes from a chemical reaction between nitrites and secondary amines or proteins (15) and causes DNA damage, oxidative stress, lipid peroxidation, and pro-inflammatory cytokine activation, which together leads to increased cellular degeneration and death (14). While nitrite is used in all processed and preserved foods, it is used heavily in fertilizers (16-17) and is a major component of polluted water. Thus, the researchers suggest to eliminate the use of nitrites in food, reduce the nitrate levels in fertilizer and water used to irrigate crops, and finally, employ safe and effective measures to detoxify food and water prior to human consumption (14). These findings were later confirmed with many other studies that showed the role of chemical fertilizers in Alzheimer's disease (18-19). Toxic concentrations of cadmium and aluminum in the soil due to the use of chemical fertilizers also plays a role in the process and pathophysiology of Alzheimer's, which was reported by another group in Hungary (20). All in all, a wealth of research suggests that chemical fertilizers pose a risk to human health and contribute to the development of chronic disease.

Nutritional Differences Between Organic and Inorganic Food

Additionally, numerous studies have reported higher levels of antioxidants in organic produce when compared to conventional produce. For example, in a ten year study at the University of California, Davis in the Department of Food Science and Technology and Department of Plant Sciences, they reported that organic tomatoes contain 79% and 97% higher levels of antioxidants quercetin and kaempferol, respectively (21). Another research team studying the difference in the vitamin C levels between organic and conventional oranges found that the levels were higher in organic oranges (22). In another study performed in Italy investigating the effect of an organic Mediterranean diet and even organic red wine, results showed that the organic wine contained higher levels of resveratrol, polyphenols, and other antioxidants than conventional wine and that organic food overall has a higher oxygen radical absorbing capacity than conventional food, due to higher antioxidant capacity and bioactivity (23).

What’s the Takeaway?

Because of the widespread, long term use of chemical fertilizers (and pesticides), we are all exposed to the negative impact in some way. Our environment has been disrupted and it will take time and change to bring it back into balance. But though we can’t avoid the detrimental effects of chemical fertilizers entirely, we can certainly reduce the impact by eating organic foods. When you consider all of the research presented, organic food is a significant game changer in the process of preventing and reversing Alzheimer’s disease and other chronic diseases. Eating organic, seasonal produce, which is basically going back to how we were growing and eating decades ago, not only reduces the harmful effect of chemical fertilizers, but also provides better nutrition quality. Unfortunately, organic food is more expensive, but the research presented here shows that you are getting more for you money in terms of nutrient density. In the end, our life is all about our choices, every time you put a forkful in your mouth, take a moment- is that food promoting health, or contributing to chronic disease?


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