Organic Pollutants: Pesticides And Their Harmful Effects

Pesticides are substances used to repel, destroy, or control pests or regulate plant growth. They are used in organic and conventional crop production systems. Pesticides can be synthetic or naturally occurring, with the latter being derived from compounds produced in nature. While naturally occurring pesticides are not synthetic, they tend to be less potent and break down more quickly in the environment, reducing the risk of harm to non-target organisms. However, some naturally occurring substances, such as arsenic and nicotine sulfate, are highly toxic to humans and other organisms and are prohibited in organic production. On the other hand, synthetic pesticides are associated with higher toxicity and broader pest activity, potentially affecting many non-target organisms. Certain pesticides, including some organic variants, are considered persistent organic pollutants (POPs), which are hazardous chemicals that threaten human health and ecosystems, causing biodiversity loss and adverse effects on non-target organisms. POP pesticides are a global concern, with international agreements seeking to reduce or eliminate their production and use.

Pesticides can be toxic to humans and the environment

Pesticides are chemical constituents used to prevent or control pests, including insects, rodents, fungi, weeds, and other unwanted organisms. They are either natural or chemically synthesized compounds.

Furthermore, the overuse or misuse of pesticides can have detrimental effects on the environment. They can poison agricultural soil, reduce its resilience, and interfere with natural nutrient cycles. Pesticides can also be transported over long distances, impacting ecosystems far from the source of pollution. Some pesticides are highly persistent in the environment and have a high potential for bioaccumulation and biomagnification, especially in aquatic environments. This can lead to the decline of biodiversity, including a significant decrease in insect populations, as observed in a study from Germany.

It is important to note that not all pesticides have the same level of toxicity. Biopesticides, for instance, tend to be less toxic than conventional pesticides as they often target specific pests and break down quickly in the environment. Reduced-risk pesticides are another option for growers concerned about minimizing risks to human and environmental health. These pesticides have lower use rates, reduced impact on human health, and lower toxicity to non-target organisms.

To address the potential risks associated with pesticides, regulatory bodies such as the Environmental Protection Agency (EPA) in the United States play a crucial role. The EPA conducts human health risk assessments for pesticides and determines the necessary precautions and restrictions based on their toxicity. Internationally, the Stockholm Convention, which entered into force in 2004, obliges its parties to eliminate or restrict the production and use of certain highly hazardous pesticides listed in its annexes.

Pesticides can be natural or synthetic

Pesticides are substances or a mixture of substances with chemical or biological ingredients intended for repelling, destroying, or controlling pests or regulating plant growth. They can be natural or synthetic.

Natural pesticides

Natural pesticides are derived from compounds produced in nature, such as diatomaceous earth and biological control agents. They are not synthetic and tend to break down quickly in the environment, reducing the risk of harm to non-target organisms. However, they may require repeated applications to be effective against pests. Natural pesticides are often less potent than synthetic pesticides, but some naturally occurring substances, such as arsenic and nicotine sulfate, are highly toxic to humans and other organisms.

Synthetic pesticides

Synthetic pesticides are substances formulated or manufactured by a chemical process or by chemically altering substances extracted from natural sources. They are often referred to as conventional pesticides and are designed to target specific species, thereby carrying little health risk for non-target species. Synthetic pesticides act quickly because they are engineered to target and disrupt specific biological functions within the intended pest. They are also often less expensive than natural alternatives.

Environmental impact

The overuse or misuse of pesticides can have detrimental effects on the environment. Pesticides can poison agricultural soil, reduce its resilience, and interfere with natural nutrient cycles. Persistent organic pollutants (POPs) are man-made hazardous chemicals found in pesticides that threaten human health and the planet's ecosystems, potentially causing biodiversity loss.

Regulation

The United States Department of Agriculture (USDA) distinguishes between synthetic and non-synthetic substances for use in organic farming. The USDA compiles a National List of approved and prohibited substances for organic production. Some synthetic pesticides, such as copper sulfate and paracetic acid, meet the criteria for use in organic agriculture.

Sustainable gardening

Sustainable gardening is a method of gardening that causes no harm to the environment. It employs integrated pest management methods, encouraging beneficial insects, minimal pesticide use, and organic and biological controls. Home composting allows gardeners to create their own natural plant fertilizers while conserving water.

Organic pesticides may have a higher environmental impact

Pesticides are substances or mixtures of substances with chemical or biological ingredients intended for repelling, destroying, or controlling pests or regulating plant growth. Some pesticides are Persistent Organic Pollutants (POPs), which are man-made hazardous chemicals that threaten human health and the planet's ecosystems, potentially causing biodiversity loss.

Organic pesticides are derived from compounds that are produced in nature, such as diatomaceous earth and biological control agents. They are not synthetic and tend to break down quickly in the environment, reducing the risk of harm to non-target organisms. However, some naturally occurring substances are very toxic to humans and other non-target organisms. For example, arsenic and nicotine sulfate are prohibited in certified organic production due to their toxicity.

While organic pesticides are generally considered more environmentally friendly than conventional pesticides, some studies have found that they can have a higher environmental impact. For instance, a study by the University of Guelph found that organic pesticides required larger doses and were more harmful to pests that help protect crops compared to synthetic pesticides. The study compared the effectiveness and environmental impact of organic and synthetic pesticides on soybean crops. The results showed that the organic pesticides had a potentially higher environmental impact because they required larger doses.

Another study by PLOS One examined the environmental impact of several new synthetic and certified organic insecticides for soybean aphid control. The results showed that the organic insecticides had a similar or even greater negative impact on several natural enemy species in lab studies and were more detrimental to biological control organisms in field experiments. They also had higher Environmental Impact Quotients at field use rates.

It is important to note that not all organic pesticides have a higher environmental impact than synthetic pesticides. Some organic pesticides, such as biopesticides, are designed to target specific pests and have lower toxicity to non-target organisms. They also have a lower potential for groundwater contamination and a lower risk of developing pesticide resistance. However, they may require repeated applications to be effective against pests.

Misuse or overuse of pesticides can poison agricultural soil

Pesticides are substances or mixtures of substances with chemical or biological ingredients intended for repelling, destroying, or controlling pests or regulating plant growth. While pesticides are useful in agriculture, their misuse or overuse can poison agricultural soil.

A study published in the academic journal Frontiers in Environmental Science found that pesticides widely used in American agriculture pose a grave threat to organisms that are critical to healthy soil, biodiversity, and soil carbon sequestration to fight climate change. The study, conducted by researchers at the Center for Biological Diversity, Friends of the Earth U.S., and the University of Maryland, is the largest and most comprehensive review of the impacts of agricultural pesticides on soil organisms. The researchers compiled data from nearly 400 studies, finding that pesticides harmed beneficial soil-dwelling invertebrates, including earthworms, ants, beetles, and ground-nesting bees, in 70.5% of cases reviewed.

Pesticides can remain in the soil for years or decades, continuously harming soil health. They can also interfere with natural nutrient cycles and reduce the soil's resilience. For example, in the Catatumbo delta, extensive amounts of pesticides have been used to fumigate illegal crops, posing a threat to the environment. In another instance, the use of low-lying wetlands for rice cultivation in St. Kitts and Nevis has resulted in agricultural pollution due to the heavy use of pesticides.

The continuous use of pesticides does not allow soil communities to recover. Additionally, the use of pesticide-coated seeds increases soil organisms' exposure to toxic chemicals. For instance, seeds treated with insecticides like neonicotinoids are placed directly into the soil, where most of the pesticide remains. Neonicotinoids are particularly harmful to insects, and their use has made U.S. agriculture 48 times more toxic to insect life.

To address these issues, it is essential to reduce pesticide use and promote ecological farming methods that help biodiversity flourish both above and below ground. Farming practices such as cover cropping and composting build healthy soil ecosystems and reduce the need for pesticides. Additionally, the use of biopesticides, which are typically less toxic and have a lower impact on human health, can be explored as an alternative to conventional pesticides.

Pesticides can be transported long distances by wind and water

Pesticides are substances or a mixture of substances with chemical or biological ingredients that repel, destroy, or control pests. They are applied to agricultural land, non-crop land, and urban areas. Pesticides can be transported long distances by wind and water, impacting both human health and the environment.

Pesticides can be transported by wind through a process called spray drift, where pesticide particles are carried by wind or air currents beyond the targeted area. The smaller the droplet size, the higher the potential for airborne transport and the greater the risk of spray drift. Wind speed, temperature, and humidity all influence the off-target movement of pesticides. Pesticides with higher volatility are more likely to turn into gases or vapors, especially under conditions of low relative humidity and higher temperatures.

Water is another critical medium for the long-distance transport of pesticides. Pesticides can enter water systems through various pathways, including runoff from agricultural and urban land, seepage from contaminated soils, and deposition from the atmosphere. Highly soluble pesticides are more likely to move with surface water or leach through the soil. Grass buffer strips are effective in reducing pesticide runoff by trapping sediment and slowing down runoff water.

The atmosphere plays a significant role in the long-distance transport of pesticides. Pesticides can enter the atmosphere through drift and evaporation during spraying, volatilization from crops and soils, wind erosion, and emissions from manufacturing and disposal processes. Once in the atmosphere, pesticides can be transported over long distances, leading to widespread contamination of soils, water bodies, crops, and the air itself.

The transport of pesticides over long distances has raised concerns about their potential adverse effects. Pesticides that are transported and deposited in new areas can contaminate soils, water sources, and ecosystems, posing risks to human health and the environment. The impact of pesticide transport is particularly evident in regions where large amounts of pesticides are applied, such as in agricultural intensification and land use, contributing to biodiversity loss and ecological degradation.

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