Human Health Hazards from Ag Plastics

Agricultural plastics play a vital role in modern farming practices, contributing to increased crop yields, water conservation, and overall efficiency.  Agricultural plastics encompass a wide range of materials used in farming operations, including but not limited to polyethylene films, polypropylene twines, plastic mulches, and drip irrigation systems. These plastics are employed for diverse purposes such as protection from the elements, weed control, moisture retention, and enhancing overall agricultural productivity.

The low cost and functionality of agricultural plastics have contributed to their increasingly widespread use by farmers in Pennsylvania. Dairy producers, who constitute the largest agricultural sector in Pennsylvania (25% of total sales), produce the largest amount of plastic waste in ear tags, silage bags, feedbags, bale wraps, nets, and twines. Due to contamination and the cost of separation and collection, most of these products end up burned or in landfills.

Mulch film used to control temperature and moisture, prevent weed growth, and improve yield is another common Ag plastic waste in Pennsylvania. Plastic film has quickly replaced organic mulch such as straw, bark, and leaves due to low cost, functionality, and versatility. However, most of the plastic mulch used on farms is difficult to collect; it thus remains exposed to UV light and breaks down. The microplastics resulting from this process are increasingly detected in farm soil and waterways due to this phenomenon.

The pervasive use of plastic materials by Pennsylvania farmers has raised concerns about potential human health hazards; this is especially relevant when disposal is done improperly. This article explores various aspects of agricultural plastics and their possible impacts on human health, shedding light on the associated risks and potential mitigation options.

Human Health Hazards of Ag Plastics

Chemical Exposure:
One of the primary concerns regarding the use of agricultural plastics is the potential for chemical exposure. Plastic materials often contain additives such as plasticizers, stabilizers, and flame retardants. Over time, these additives can leach into the soil and water, leading to contamination. Moreover, ag plastics may be used for pesticide application and are thus contaminated with those chemicals.  Prolonged exposure to chemicals may pose health risks to farmworkers and nearby communities.

Endocrine Disruption:
Some additives found in agricultural plastics have been linked to endocrine disruption. Endocrine-disrupting chemicals (EDCs) can interfere with the body's hormonal systems, potentially leading to reproductive and developmental issues. The long-term consequences of chronic exposure to EDCs in agricultural plastic residues are an area of ongoing research.

Microplastic Contamination:
Agricultural plastics, when exposed to environmental factors like sunlight and weathering, can break down into microplastics—tiny particles less than 5 millimeters in size. These microplastics can contaminate soil and water, posing a potential risk to human health through the food chain. Ingestion of microplastics has been associated with various health concerns, though the full extent of these risks is still being studied.

Respiratory Health Risks:
Farmworkers involved in the application and removal of plastic films and mulches may be exposed to airborne particles and dust-containing plastic residues. Inhalation of these particles could lead to respiratory issues and pose health risks, especially in the absence of proper protective measures.

Occupational Exposure:
Workers involved in the agricultural sector, including those engaged in the application and removal of plastic materials, are at an increased risk of direct exposure to potentially hazardous substances. Occupational safety measures, training programs, and the provision of personal protective equipment are vital components of minimizing health risks associated with plastic use on farms.

Heat-Related Concerns:
Plastics used in agriculture, such as plastic mulches, can contribute to soil warming. While this can be beneficial in colder climates like Pennsylvania and for specific crops, prolonged exposure to elevated temperatures may impact soil ecology and microbial activity. Additionally, the increased heat in the working environment can pose health risks to farmworkers, particularly during hot seasons.

Skin Contact Irritation:  
Direct contact with agricultural plastics can lead to skin irritation, especially if farmworkers handle these materials without adequate protection. Skin disorders may arise due to prolonged exposure to certain additives or chemical/pesticide residues present in the plastics; this reinforces the importance of proper handling practices and protective gear.

Mitigation Strategies

Alternative Materials:
Farm operators should consider adopting alternative materials that are biodegradable or have a lower environmental impact and can help reduce the reliance on traditional agricultural plastics.

Protective Measures for Farmworkers:
Providing farmworkers with adequate protective gear, such as gloves, masks, and clothing, can significantly reduce direct exposure to agricultural plastics and the associated chemicals that often adhere to them. Training programs should emphasize safe handling and disposal practices to mitigate health risks.

Proper Disposal Practices:
Implementing proper disposal practices for agricultural plastics is crucial for both human and environmental health. Encouraging recycling, reuse, or appropriate disposal methods can minimize environmental contamination and reduce the risks associated with chemical leaching.

Excluding ear tags, which are complicated to recycle due to electronic parts, most of the plastic waste produced by dairy producers are recyclable in theory.  While mulch film is recyclable, it requires timely collection, bailing (which most small farmers cannot do), and a rigourous cleaning process that increases the cost of recycling for the dairy industry.

Our research suggests that the ag plastics recycling system in Pennsylvania is inadequate and is not often used by farmers. One of the unfortunate outcomes from this situation is that a significant portion of the used ag plastics is disposed of by burning on the farm.  As noted below, this option presents numerous downsides and should be avoided.

Specific hazards related to plastics disposal via burning

Open burning is technically legal in Pennsylvania under certain circumstances (see PA Code 129.14 for details), and is commonly used by farmers.  However, the disposal of plastics, including common agricultural plastics, through burning (e.g., open pits) or incineration poses specific hazards to both the environment and human health.  While burning may seem like an easy way to eliminate on-farm plastic waste, the process releases a variety of pollutants and toxic substances and should be avoided or carefully managed.  Below are some of the specific hazards associated with the burning of plastics:

Air Pollution:
The combustion of plastics releases a complex mixture of air pollutants, including carbon monoxide, nitrogen oxides, sulfur dioxide, and volatile organic compounds (VOCs). These pollutants contribute to air pollution and can have adverse effects on respiratory health when inhaled. Prolonged exposure to these pollutants may lead to respiratory problems and exacerbate existing conditions such as asthma.

Toxic Emissions:
Plastics often contain a variety of additives, including flame retardants, plasticizers, and stabilizers. When burned, these additives can generate toxic emissions such as dioxins, furans, and other hazardous compounds. Dioxins, in particular, are persistent organic pollutants known for their toxicity and potential to cause a range of adverse health effects, including cancer and reproductive disorders. Plastics used around a farm may have additional contaminants that would result in more toxic emissions.

Particulate Matter:
The burning of plastics produces fine particulate matter that can be carried by air currents over long distances. Inhalation of these fine particles can penetrate deep into the respiratory system, causing respiratory and cardiovascular problems. Particulate matter is also associated with an increased risk of lung diseases and other respiratory issues.

Soil and Water Contamination:
The ash resulting from the burning of plastics may contain residual toxic substances, including heavy metals and other contaminants. Improper disposal of ash can lead to soil and water contamination, affecting ecosystems and potentially entering the food chain. The long-term environmental impact of these contaminants can be substantial.

Greenhouse Gas Emissions:
Burning plastics contributes to the release of greenhouse gases, including carbon dioxide (CO₂) and methane (CH₄). While these emissions may not be as potent as certain pollutants, they still contribute to climate change and global warming.

Incomplete Combustion:
Incomplete combustion from a smoldering plastic fire can result in the formation of black carbon (soot). Black carbon is associated with a variety of respiratory and cardiovascular health problems and has environmental implications.

Conclusions

Our research has shown that burning is a common practice for plastic waste disposal in some Pennsylvania agricultural settings; this practice poses significant risks to both human health and the environment.  Youth are especially at risk and should not be allowed to burn plastics or be close to burn pits during operation.

Sustainable waste management practices that prioritize recycling, reuse, and other proper disposal methods should be encouraged to minimize the adverse impacts associated with burning plastics.  The ag plastics recycling system in Pennsylvania is available to most farmers but the economics make it difficult for it to grow as fast as needed.  Our research programs are currently investigating ag plastics recycling in Pennsylvania and we hope to make suggestions on how it can be improved.

While agricultural plastics have revolutionized modern farming practices, their widespread use raises valid concerns about human health hazards. Addressing these issues requires a multifaceted approach, encompassing consideration of alternative materials, proper disposal practices, and protective measures for farm workers. By fostering sustainable practices and staying informed about the potential risks, Pennsylvania’s agricultural industry can strive for a balance between productivity and the well-being of both the environment and human populations.

Acknowledgments:  This work was supported in part by a grant from the Pennsylvania Department of Agriculture, and in part by the Nationwide Insurance Endowment for Ag Safety & Health.