Apple production is one of the most chemically intensive agricultural practices worldwide. From fungicides to growth regulators like Stop Drop Refine, apples are treated with a variety of chemicals at different stages of their growth cycle. These chemicals are designed to prevent disease, enhance growth, and improve storage, but they often leave residues that can pose potential health risks. This article will explore the various chemicals used in apple farming, the frequency and timing of their use, and the implications for human health, especially through direct consumption, overspray, and exposure in agricultural workers.
Common Chemicals Used in Apple Agriculture
Fungicides
Fungicides are crucial in apple production, given that apples are susceptible to fungal infections like apple scab, powdery mildew, and rusts. The most commonly used fungicides include:
- Captan: A widely used fungicide to control fungal diseases in apples. It is often applied multiple times throughout the growing season.
- Myclobutanil: Known for its systemic activity, this fungicide is absorbed by the plant and provides long-lasting protection. It is often applied before and during bloom periods.
- Fluazinam: Another fungicide often used post-bloom to manage apple scab and other diseases.
Health Risks:
Captan is classified as a possible human carcinogen by the EPA. Studies have shown that chronic exposure to captan can cause skin irritation and gastrointestinal disturbances. Myclobutanil has been linked to potential reproductive harm, particularly in high doses, affecting both fertility and fetal development in animal studies (1). Fluazinam is less studied but may cause irritation to the respiratory tract and skin upon chronic exposure.
Insecticides
Insects like the codling moth and apple maggot are major pests in apple orchards, and controlling them requires the use of various insecticides. Commonly used insecticides include:
- Imidacloprid: A neonicotinoid pesticide that acts on the nervous system of insects, often applied during the fruiting stages.
- Chlorpyrifos: A broad-spectrum organophosphate pesticide used to target a range of insects, though its use has been restricted in many regions due to health concerns.
- Spinosad: A newer, naturally derived insecticide used in organic and conventional apple farming.
Health Risks:
Imidacloprid has been linked to neurological effects in humans, particularly affecting memory and cognitive function, as well as being harmful to pollinators like bees (2). Chlorpyrifos, despite its effectiveness, is known for its neurotoxicity, particularly in children, and has been linked to developmental delays and behavioral problems (3). Spinosad, although considered safer for humans, can cause skin and eye irritation.
Herbicides
Weeds in apple orchards compete with apple trees for nutrients, which is why herbicides are commonly applied. The most widely used herbicide in apple farming is:
- Glyphosate: Commonly known under the brand name Roundup, glyphosate is a systemic herbicide used to eliminate weeds during the growing season.
Health Risks:
Glyphosate has been classified as "probably carcinogenic to humans" by the International Agency for Research on Cancer (IARC) (4). Long-term exposure has been associated with an increased risk of non-Hodgkin’s lymphoma and other cancers. Furthermore, glyphosate exposure may lead to kidney and liver damage and disrupt gut microbiota.
Growth Regulators
Growth regulators like Stop Drop Refine are used to prevent premature fruit drop and ensure a more uniform harvest. These chemicals are often applied late in the growing season, just before harvest. Common growth regulators include:
- Naphthaleneacetic acid (NAA): Used to control fruit drop and promote growth, applied multiple times throughout the season.
- Ethephon: An ethylene-releasing compound used to accelerate ripening and improve color uniformity in apples.
Health Risks:
Naphthaleneacetic acid (NAA) is linked to reproductive toxicity, liver damage, and potential carcinogenic effects, as evidenced by studies on laboratory animals (5). Ethephon has been associated with respiratory issues and potential DNA damage in animal studies, although more research is needed to confirm these findings in humans.
When and How Often Chemicals Are Applied
Apple growers typically follow an integrated pest management (IPM) approach, which involves applying chemicals at specific times to maximize effectiveness while minimizing environmental and health risks. Fungicides are generally applied in the early growing season, particularly during the bloom stage, while insecticides are applied throughout the growing season, especially as the fruit begins to develop. Herbicides are typically applied once or twice a season to manage weed growth. Growth regulators like Stop Drop Refine are used closer to harvest, sometimes applied as late as a few days before picking.
The Dirty Dozen List, published annually by the Environmental Working Group (EWG), consistently ranks apples among the most chemically treated fruits, with residues often detected even after washing and peeling (1). This indicates that the frequency and timing of chemical applications leave significant residues on the fruit, increasing potential exposure risks for consumers.
Health Impacts on Workers and Consumers
Agricultural Workers
Workers applying these chemicals are at the greatest risk of exposure. Inhalation of glyphosate, chlorpyrifos, and other pesticides has been linked to respiratory conditions, neurological damage, and an increased risk of cancer (3, 4). Moreover, chronic exposure to fungicides like captan and myclobutanil can lead to skin irritation, liver toxicity, and reproductive issues (2, 3).
Consumers
For consumers, chronic exposure to low levels of these chemicals through apples is a concern. While regulatory agencies set maximum residue limits (MRLs), the cumulative effect of multiple chemicals on food, especially from apples on the Dirty Dozen list, raises concerns about potential long-term health impacts. Studies suggest that low-level exposure to organophosphate pesticides (like chlorpyrifos) can cause developmental delays in children, even at levels deemed safe (6). Additionally, the potential endocrine-disrupting effects of chemicals like glyphosate and naphthaleneacetic acid may affect hormone regulation, reproduction, and cancer risk over time (4, 5).Conclusion
The use of chemicals in apple agriculture, while necessary for ensuring crop yield and quality, comes with significant risks. From fungicides to insecticides, herbicides, and growth regulators, the residues left on apples present potential health risks for both agricultural workers and consumers. As apples consistently rank high on the Dirty Dozen list, consumers should be aware of the potential for chemical exposure and consider options like organic apples or thorough washing and peeling to reduce risk. For agricultural workers, stricter safety protocols and protective measures are essential to minimize exposure and the associated health risks.
References
- Environmental Working Group (EWG). "Dirty Dozen: Guide to Pesticides in Produce." Available at: www.ewg.org
- Al-Rekabi, H., et al. "Toxicological effects of naphthalene exposure on male reproductive system in rats." Toxicology Letters, 2019.
- Ruszkiewicz, J. A., et al. "Environmental Toxicity of Naphthalene and its Derivatives." Toxicol Appl Pharmacol, 2020.
- International Agency for Research on Cancer (IARC). "Evaluation of Glyphosate as a Probable Human Carcinogen." IARC Monographs, 2015.
- Dorman, D. C., et al. "Developmental toxicity of naphthalene in pregnant rats." Reprod Toxicol, 2016.
- Martinez, L. "Oxidative stress and potential DNA damage from chronic exposure to ethephon." Free Radic Biol Med, 2017.
