Human Toxicity: Carcinogenic Contributions: To evaluate the potential impact of harmful substances released throughout the eyeglasses' lifecycle that may contribute to cancer risks in humans.
Raw material extraction: Exposure to heavy metals or other carcinogenic substances used in mining or polymer production may pose cancer risks to workers and surrounding communities.
Manufacturing: Certain chemicals used in coatings, dyes, and plastic molding may release carcinogenic pollutants into the air or water during production.
End-of-life/disposal: Inappropriate disposal or incineration can release carcinogens into the environment, affecting nearby populations through air and soil contamination.
Human Toxicity: Non-Carcinogenic Contributions: To assess the potential for substances used or emitted throughout the product lifecycle to cause non-cancer-related health effects in humans (e.g., respiratory, neurological, or organ damage).
Raw material extraction: Mining and processing of materials like rare metals and plastics may release non-carcinogenic toxicants into local water and soil systems.
Manufacturing: Emissions of solvents, plasticizers, or flame retardants during lens coating or frame production can contribute to human health risks such as endocrine disruption or organ toxicity.
Use & disposal: Wear and degradation of materials (especially low-quality plastics or coatings) might release trace chemicals that pose non-carcinogenic risks over time.
Global Warming Potential: To evaluate the contribution of eyeglasses to climate change by measuring greenhouse gas emissions across each life cycle phase.
Raw material extraction: Energy-intensive mining and processing operations result in significant CO₂ and methane emissions.
Manufacturing: Production processes such as injection molding, lens grinding, and coating involve high energy use and fossil fuel consumption, contributing to GHG emissions.
Transportation: Movement of raw materials, components, and finished eyeglasses—especially international shipping—releases CO₂ and other GHGs due to fuel combustion.
End-of-life: Landfilling or incineration of synthetic components can release additional GHGs
Chart 1: General GWP Contribution
This pie chart illustrates the contribution of different stages in the life cycle of eyeglasses to GWP.
The market for electricity remains a significant factor in these emissions, particularly because much of the energy consumed in manufacturing and transport still comes from non-renewable sources. This points to a potential opportunity for the eyeglass industry to reduce its GWP by switching to cleaner energy sources and optimizing manufacturing processes.
Manufacturing (Energy & Emissions): The production process of lenses and frames involves significant energy consumption, primarily due to the heating processes involved in shaping and coating the materials. The energy used in manufacturing can contribute up to 3.9% of the GWP in the eyeglass lifecycle. Although some manufacturing facilities use renewable energy sources, many still rely on fossil fuels, which further increase the carbon footprint.
Transportation (Emissions from Transporting Materials): The transportation phase, while a smaller portion in the provided analysis, still contributes to GWP. Long-distance transportation of raw materials, intermediate goods, and finished products involves fuel consumption, contributing to the overall carbon footprint. As with other global supply chains, transportation-related emissions are often significant when products are sourced or sold internationally.
Chart 2: Human Toxicity: Carcinogenic Contributions
The human toxicity charts reflect the carcinogenic risks associated with eyeglass production.
Manufacturing: The production of lenses and frames involves chemicals that may be carcinogenic. For example, the processes to make certain types of glass and plastic coatings can release toxic substances, including solvents, which pose carcinogenic risks to workers. Additionally, the extraction of materials like titanium can involve the use of hazardous chemicals, potentially increasing the exposure to carcinogens in mining areas.
Transportation and Disposal: While less impactful, transportation of these materials might also introduce exposure risks, especially if the transportation systems use older or poorly regulated vehicles. Furthermore, improper disposal of eyeglasses, especially if they contain harmful chemicals, can lead to the release of carcinogenic substances into the environment.
Chart 3: Human Toxicity: Non-Carcinogenic Contributions
The non-carcinogenic human toxicity contributions, similar to carcinogenic risks, are mainly associated with the chemicals used in manufacturing eyeglasses. These include:
Solvents and Chemicals in Manufacturing: Solvents used in the lens coating process or frame production can release non-carcinogenic but harmful chemicals. These chemicals might cause long-term health issues such as organ damage, respiratory problems, or skin irritation. Their impact on workers' health, especially in poorly regulated facilities, could be significant. Non-carcinogenic risks might be compounded in developing regions where labor laws might not adequately protect workers from exposure.
End-of-Life Disposal: Improper disposal of eyeglasses could exacerbate these issues, as chemicals from lenses and frames may leach into the environment, posing health risks to those living near landfills or in areas where waste management practices are insufficient. Additionally, some plastics and coatings used in eyeglasses may contain hazardous substances that can cause non-carcinogenic health effects if improperly disposed of.