Cadmium Telluride - Toxicity

Toxicity

Cadmium telluride is toxic if ingested, if its dust is inhaled, or if it is handled improperly (i.e. without appropriate gloves and other safety precautions). Once properly and securely captured and encapsulated, CdTe used in manufacturing processes may be rendered harmless. CdTe appears to be less toxic than elemental cadmium, at least in terms of acute exposure.

The toxicity is not solely due to the cadmium content. One study found that the highly reactive surface of cadmium telluride quantum dots triggers extensive reactive oxygen damage to the cell membrane, mitochondria, and cell nucleus. In addition, the cadmium telluride films are typically recrystallized in a toxic solution of cadmium chloride.

The disposal and long term safety of cadmium telluride is a known issue in the large scale commercialization of cadmium telluride solar panels. Serious efforts have been made to understand and overcome these issues. A document hosted by the U.S. National Institutes of Health dated 2003 discloses that:

Brookhaven National Laboratory (BNL) and the U.S. Department of Energy (DOE) are nominating Cadmium Telluride (CdTe) for inclusion in the National Toxicology Program (NTP). This nomination is strongly supported by the National Renewable Energy Laboratory (NREL) and First Solar Inc. The material has the potential for widespread applications in photovoltaic energy generation that will involve extensive human interfaces. Hence, we consider that a definitive toxicological study of the effects of long-term exposure to CdTe is a necessity.

Researchers from the U.S. Department of Energy's Brookhaven National Laboratory have found that large-scale use of CdTe PV modules does not present any risks to health and the environment, and recycling the modules at the end of their useful life completely resolves any environmental concerns. During their operation, these modules do not produce any pollutants, and, furthermore, by displacing fossil fuels, they offer great environmental benefits. CdTe PV modules appear to be more environmentally friendly than all other current uses of Cd.

The approach to CdTe safety in the European Union and China is much more cautious: cadmium and cadmium compounds are considered as toxic carcinogens in EU whereas China regulations allow Cd products for export only.