Q: Geosynthetics are made from polymers that use metal-based catalysts in their formulations. Do geosynthetics have the potential to leach metals into the environment?
A: I think the fair answer to this is yes, but the potential risk is very small due to the long-term stability of the polymers used in geosynthetics and the very low concentration of such metals in the formulation. There are many scholarly articles on the web in this regard.
That written, I would like you to consider the very large benefit of geosynthetics (particularly geomembranes) as compared to the relatively small risk that they pose to the environment when serving as part of a barrier for containment of waste. Note that geomembranes, and, in particular, high-density polyethylene (HDPE) geomembranes, have no natural equivalents to my knowledge.
Before work begins on any construction project, contractors need to verify that the selected geosynthetics are fit for use. They must take responsibility for acceptance of manufactured or fabricated materials and products. Contractors need to verify that the geosynthetics in question are listed as approved (National Transportation Product Evaluation Program, DataMine, Caltrans, etc.). Geosynthetics are not allowed to be used on sites until certificates of compliance have been submitted and certified. In addition, contractors must ensure that geosynthetics are properly covered for protection against damage prior to use (unless specifically designed to be exposed) and that they do not pose a risk to human health and the environment.
The path to quality begins with resins and masterbatches from which geosynthetics are formulated. Suppliers of these polymers have a commitment to customer service. Most manufacturers have technical support teams with expertise and experience to address environmental challenges. They conduct their operations in a safe, clean, responsible manner, often conforming to rigorous international quality standards. They strive to do business in an environmentally sustainable way and monitor their operations to make optimal use of the resources they consume while reducing emissions and waste. Many are supporting members of the Alliance to End Plastic Waste (www.endplasticwaste.org). The products they make contribute to a sustainable future and cost less than alternatives.
If this is not satisfactory to you, perhaps a toxicity characteristic leaching procedure (TCLP) test is in order. One can also perform such a test on aged materials.