End-of-life management is important for addressing large future photovoltaic (PV) waste volumes and conserving raw materials for use in new PV modules. In regions without regulatory mandates for PV recycling, end-of-life PV modules can be disposed in accordance with general waste laws. Given the use of various metals as raw materials in semiconductor compounds and electrical contacts in commercial PV modules, some stakeholders have raised concerns regarding potential environmental impacts if PV modules are subject to improper disposal instead of being recycled or disposed in sanitary landfills, as is required in most world regions. To evaluate these concerns, screening-level risk assessment methods are developed herein that evaluate potential human health risks from groundwater and surface (air, soil, surface water) exposure pathways. The methods estimate potential impacts from disposal of end-of-life (EOL) PV modules in non-sanitary landfills under the following worst-case conditions: no leachate collection or groundwater monitoring, no liner for preventing leachate migration, uncovered waste, and lack of stormwater management. Examining worst-case conditions allows the exploration of maximum potential risk to attempt to ensure disposal does not increase health risk above regulatory thresholds.
Specifically, this report presents an analysis of potential human health risks associated with non-sanitary landfill disposal for three PV technologies, focusing on release of the highest-prioritized chemical element for each: lead (Pb) in crystalline-silicon (c-Si) PV modules, cadmium (Cd) in thin film cadmium telluride (CdTe) PV modules, and selenium (Se) in thin film copper indium selenide (CIS) PV modules. The prioritization of these chemical elements for analysis is based on stakeholder interest. Because the methodology is chemical-specific, the risk assessment results for these chemicals cannot be directly generalized to other chemicals, although the risk assessment methodology can be applied to other chemicals. If the chemicals chosen are indeed the ones presenting greatest risk, then the results herein should represent the upper bound of health risk from exposure to a single constituent.
Under the layers of health-protective assumptions applied, for Pb for c-Si PV, Cd from CdTe PV and Se from CIS PV, cancer risks and non-cancer hazards are found to be at least one order of magnitude below the US regulatory screening thresholds of 1×10-6 cancer risk and non-cancer hazard quotient of 1. Health screening levels can differ by country or region; exposure-point concentrations in groundwater and surface water of Pb, Cd, and Se for c-Si, CdTe, and CIS PV, respectively, are also within water quality guidelines from the World Health Organization. The results presented herein do not represent a complete human health risk assessment for PV module disposal nor an assessment of cumulative risk, although the results are suggestive of low risk for the prioritized chemicals examined using best available regulatory methods. The screening-level methods employed in this report can be used in future work to assess potential health risks from other chemicals of potential concern and other PV technologies to establish a more complete set of results for chemicals of potential concern.
It is also important to note that examination of potential health risk from disposal of PV modules in landfills does not endorse this EOL management option. Indeed, recycling end-of-life PV modules would further mitigate environmental concerns, as found in several recent life cycle assessments.