Agricultural Contaminants

People living and working in rural areas are at risk of exposure to wide range of pollutants emitted from agricultural operations.

Exposure to pesticides and herbicides is a significant concern; roughly only 85% of sprayed airborne pesticides reach their target destination [1]; the remaining 15% is distributed elsewhere, as pesticide drift. The US EPA recently introduced proposed guidance on November 4, 2009 for new pesticide labeling to reduce off-target spray and dust drift. In addition to the risk of exposure to the active chemical agent, workers who spray or deposit these agents are also at risk of solvent exposure. Solvents act as vehicles to distribute the active chemical agent.

Organic farming reduces the risk of exposure to airborne pesticides and pesticides in food that enter both plant and animal food sources through water and soil. Certified organic farmers must ensure that their seeds, crops and livestock are not at risk of exposure to pesticides via drift from neighboring non-organic farming operations. Organic farming relies on insect predators and parasites, pest disease agents, bats, insect eating birds and other predators to control unwanted pest populations. In some cases, certain organic pesticides are approved for use.

Other conventional agricultural facilities and operations that can produce air contaminants (including odors and particulate matter) are CAFOs, mill operations, smokehouses, cotton gins, and hide processing. Confined Animal Feeding Operations (CAFOs) are facilities in which animals such as poultry, hogs, or cows are concentrated in a relatively small area for egg laying, stabling, sleeping, milking, or feeding purposes. Animal emissions and waste from agricultural operations can collect in the surrounding water and soil, then release odors and gases including methane gas and ammonia.

Contaminant Sources in Agriculture

Pesticides, Herbicides, Fungicides
Organic Farming
Animal Emissions

Types of Sampling

Ambient Air
Indoor Air

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Pesticides, Herbicides, Fungicides

Regulations for pesticide use vary by country. In the US, it is regulated by the Environmental Protection Agency (EPA). As a result of many studies, the EPA developed toxicity ratings/class and they are required for every registered pesticide. Some pesticides are considered extremely hazardous and their use is restricted to certified users. The European Union (EU) also has legislation regarding the use of pesticides. Elsewhere in the world, the United Nations is working to improve communication with developing countries to build awareness on pesticides hazards.

The World Health Organization (WHO) estimates over 3 million farmers in developing countries experience severe poisoning from pesticides and another 25 million suffer mild pesticide poisoning. In the US, the EPA estimates that 10,000-20,000 physician-diagnosed pesticide poisonings occur each year among the approximately 2 million U.S. agricultural workers. Agricultural workers, groundskeepers, pet groomers, fumigators, and a variety of other occupations are at risk for exposure to pesticides including fungicides, herbicides, insecticides, rodenticides, and sanitizers.

View an overview on Pesticide Classes and Exposure Hazards for commonly used pesticides, herbicides, and fungicides.

Pesticides are difficult to measure in air; as a result, they are often measured as residues in food products, water/wastewater, and soil. To learn more about solid phase extraction of pesticides from food and environmental samples, view the following content under the SPE portal:
Multi-layer SPE for Pesticide Analysis
Dispersive SPE (QuEChERS)
SPE Literature and Application Notes

Sampling Media

Common methods for sampling pesticides in air include: drawing air through a 25 mm GF/A filter with a Tenax TA tube connected in series; or using an OSHA Versatile Sampler (OVS) packed with XAD-2 and a quartz or glass fiber filter (20350); or using a Polyurethane Foam (PUF) sampler.

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Organic Farming

The pesticides permitted in organic farming fall into the following predominant classes.

Minerals: These include sulfur, copper, diatomaceous earth, and clay-based materials.

Botanicals: Botanicals include common commercial materials such as rotenone, neem, and pyrethrum. Less common botanicals include quassia, equisetum, and ryania.

Soaps: A number of commercial soap-based products are effective as insecticides, herbicides, fungicides, and algicides. Detergent-based products are not allowed for crop use in organic production.

Pheromones: Pheromones can be used as a means to confuse and disrupt pests during their mating cycles, or to draw them into traps.

Biologicals: One of the fastest-growing areas in pesticide development, biopesticides present some of the greatest hope for organic control of highly destructive pests. Among the most well known bio-pesticides are the Bacillus thuringiensis (Bt) formulations for control of lepidopterous pests and Colorado potato beetle.

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Animal Emissions

Animal emissions emanate from animal feedlots, waste ponds and lagoons, and land spreading of manure based fertilizers. The most commonly known animal emission is methane gas – a result of flatulence and waste from ruminant animals (cows, sheep, goats); also due to microbial degradation of organic matter. The amount of methane gas produced is directly related to the type of feed the animal receives as well as other factors such as animal type, age, etc. Other emissions of interest are ammonia from animal manure, hydrogen sulfide from degradation of sulfur containing organic matter in manure, and nitrous oxide from microbial processes via nitrification of aerobic soils and carbon dioxide.

Currently OSHA Personal Exposure Limits do not apply to Agriculture Operations – Federal Standard 29 CFR 42:38568-9