EPQ: A* example 'To what extent do plastics affect human life and the endocrine system, and how can it be mitigated?'

Below is a curtailed version of an EPQ that achieved 45/50 in 2025/26 from Shubber Fatlawi (19FatlawiS@students.watfordboys.org)

Introduction

Every year, approximately 445 million tonnes of plastics are produced globally, a figure that reflects the material’s increasingly dominant role in modern society (1). Plastics have become deeply embedded in daily life, appearing in everything from medical devices and food packaging to construction materials and transportation systems. Their widespread use is not coincidental; rather, it stems from their unique physical and chemical properties, including durability, versatility, and low production cost (2). Plastics are synthesised polymer compounds characterised by high molecular mass and plasticity, while microplastics—particles between 1 and 1000 nanometres—arise from the degradation or production of larger plastics and display colloidal properties due to their extremely small size (3). These particles are now ubiquitous in the environment and have even been detected in human blood and placental tissue, raising urgent concerns about their potential impact on human health (5). This is particularly significant when considering the endocrine system, a complex network of glands responsible for regulating metabolism, growth, reproduction, and mood (4). Disruption to this system can have widespread and long-lasting consequences. This essay explores the dual role of plastics by examining their societal benefits, contrasting these with their harmful effects on endocrine health, and evaluating whether plastics are worth the risk. It concludes by considering potential mitigation strategies and future directions.

Benefits of plastics on human life

Plastics are integral to modern society due to their versatility, durability, and low cost. Their widespread adoption is driven by properties such as resistance to chemicals and light, high strength-to-weight ratio, and ease of processing (6). These characteristics allow plastics to be used across a wide range of industries, making them indispensable in many aspects of daily life. One of the most significant applications is in food packaging. Plastics such as polyethylene and polypropylene are widely used in bottles, cling film, and vacuum-sealed packaging, protecting food from contamination, extending shelf life, and maintaining freshness (6). Technologies such as modified atmosphere packaging further enhance preservation by controlling gas composition within packaging (7). As a result, plastics play a crucial role in reducing food wastage and improving food security, particularly in urban environments where supply chains are complex and time-dependent. Moreover, plastic packaging is often more energy-efficient than alternatives. A 2005 study comparing PET bottles with glass and metal found that plastics reduced energy consumption by 52% and greenhouse gas emissions by 55% (6). This highlights that plastics, despite environmental concerns, can provide environmental benefits in certain contexts.

Beyond food packaging, plastics play a vital role in infrastructure and construction. Polyvinyl chloride (PVC), first created in 1872, is widely used in piping, insulation, and building components due to its durability, corrosion resistance, and low cost (6). In developing regions, plastic piping systems have significantly improved access to clean water and sanitation, reducing the incidence of waterborne diseases and improving public health outcomes (9). Plastic insulation also improves thermal efficiency in buildings, reducing energy consumption and lowering household costs; for example, plastic window insulation can save 10–30% on heating and cooling expenses (8). In disaster-stricken areas, plastic sheeting is used to rapidly deploy emergency shelters due to its lightweight, durable, and easily transportable nature (10). These applications demonstrate that plastics not only address immediate needs but also contribute to long-term resilience and improved quality of life.

In medicine, plastics are indispensable. Approximately 85% of medical equipment relies on plastic components, including intravenous bags, syringes, and disposable protective equipment (11). These innovations have transformed healthcare by improving hygiene and reducing the risk of infection. Single-use syringes, for example, have been instrumental in preventing the spread of blood-borne diseases such as HIV and hepatitis B (11). Plastics are also used in advanced medical technologies, including prosthetics, implants, and drug-delivery systems, further demonstrating their importance in modern healthcare. The automotive industry also benefits significantly from plastics. By reducing vehicle weight, plastics improve fuel efficiency—a 10% reduction in weight yields a 6–8% improvement in fuel economy (12). Their design flexibility allows for more aerodynamic shapes, while polymer composites enhance safety by absorbing impact energy during collisions (13). In electric vehicles, lightweight plastic components help extend battery range, contributing to the development of more sustainable transport systems (14). These examples illustrate that plastics are deeply embedded in systems that support modern life, contributing to health, efficiency, and economic development.

Harmful effects of plastics on the endocrine system

Despite their benefits, plastics pose significant risks to human health, particularly through their impact on the endocrine system. Endocrine-disrupting chemicals (EDCs), commonly found in plastics, interfere with hormone signalling pathways and can lead to a wide range of health issues (15). Microplastics and nanoplastics have been shown to affect key endocrine glands, including the thyroid, ovaries, testes, and hypothalamus. Chemicals such as phthalates can cause thyroid epithelial cell hypertrophy, hyperplasia, and disruption of the hypothalamic-pituitary-thyroid axis, leading to altered FT3 and FT4 levels (16). Polybrominated diphenyl ethers (PBDEs) have been linked to reduced serum T4 levels, increased prevalence of hyperthyroidism, and disturbed thyroid hormone concentrations in umbilical cord blood (16). Since the thyroid plays a crucial role in regulating metabolism and brain development, disruptions can have long-lasting effects, particularly during early stages of life.

Research also indicates that exposure to plastic-associated chemicals can impair reproductive health. Mercury, for example, inhibits LH and FSH secretion, disrupts menstruation, and impairs follicular development, while in males it damages Leydig cells and reduces sperm quality (16). These disruptions can lead to infertility, miscarriage, and developmental abnormalities. Microplastics can also bioaccumulate within the body and act as carriers for toxic chemicals, binding to harmful substances in the environment and transporting them into biological systems (16). Once inside the body, they interfere with hormone production, transport, and regulation, contributing to metabolic disorders, immune dysfunction, and neurological effects. Large observational studies have linked phthalate exposure to preterm birth and insulin disruption (15). Developmental exposure to flame retardants has been associated with reduced IQ in children (15). These findings are particularly concerning for vulnerable populations such as pregnant women and infants, who are more sensitive to hormonal disruptions.

Recent research suggests that microplastics themselves, not just their chemical additives, may contribute to endocrine disruption. A Rutgers study showed that inhaled nylon micro- and nanoparticles reduced levels of 17β-estradiol even without chemical additives, suggesting that the particles themselves may have direct biological effects (17). This represents a shift in understanding, indicating that the risks associated with plastics may be broader than previously thought. A South Korean study further identified metabolic, developmental, and reproductive disorders linked to microplastic exposure, proposing that microplastics interfere with hormone production, release, transport, metabolism, and elimination (18). A key challenge in understanding the impact of plastics is that their effects often occur at very low exposure levels. Unlike traditional toxic substances, EDCs do not follow a straightforward dose-response relationship, meaning even small amounts can have significant biological effects (15). Additionally, long latency periods and cumulative exposure make it difficult to establish direct causation between plastic exposure and specific diseases.

Critical evaluation: Are plastics worth the risk?

The widespread use of plastics presents a complex trade-off between their benefits and risks. One of the most significant issues is the persistence of plastics, as they degrade very slowly and accumulate in the environment. Over time, larger plastics break down into microplastics, which can enter the food chain and ultimately the human body (3). Evidence suggests that microplastics may contribute to non-communicable diseases, including cancer (16). Another major concern is the inadequacy of current regulatory frameworks, which often fail to account for low-dose, long-term exposure to EDCs. This creates gaps in public health protection.

There is also a clear ethical dimension to this issue. The benefits of plastics are immediate, while the harms are long-term and disproportionately affect vulnerable populations, including unborn children (15). While alternatives such as biodegradable plastics exist, they are often more expensive and less durable (19). Materials such as glass or metal increase energy costs due to their weight (20). Natural fibres such as hemp, tencel, and cotton can replace synthetic textiles, reducing microplastic shedding (21). Rather than eliminating plastics entirely, a more realistic approach is to redesign materials and improve systems to reduce their harmful effects.

Mitigation and future outlook

Addressing the challenges posed by plastics requires a multi-faceted approach involving technological innovation, policy reform, and behavioural change. Improving waste management systems is essential. Advanced wastewater treatment methods can help remove microplastics before they enter ecosystems (22). Emerging technologies such as catalytic upcycling offer promising solutions, although challenges of cost and scalability remain. Bio-based plastics also provide alternatives, though they require further development (19).

Policy measures such as bans on single-use plastics and extended producer responsibility schemes can reduce plastic consumption (12). Public awareness and behavioural change are equally important. Emerging research suggests that antioxidants may help mitigate the effects of microplastic exposure, though further studies are needed (23).

Conclusion

Plastics have revolutionised modern life, providing significant benefits in healthcare, infrastructure, and everyday convenience. However, growing evidence demonstrates that microplastics and associated chemicals can disrupt the endocrine system, leading to serious health risks. While plastics remain essential, their current use is unsustainable. A balanced approach involving innovation, regulation, and behavioural change is necessary to reduce risks while retaining their benefits.