In an article published on June 22, 2020, in the peer-reviewed journal Chemosphere, Maria Luisa Astolfi and colleagues from the Department of Chemistry, Sapienza University, Rome, Italy, reported on the composition and migration of 41 inorganic elements, including “alkaline metals, alkaline earth metals, heavy metals and metalloids,” from polyhydroxyalkanoate (PHA) bioplastics derived from different types of organic waste feedstocks.
The total contents ranged from 0.0001 mg/kg PHA for beryllium (Be, CAS 7440-41-7) to 49,500 mg/kg for sodium (Na, CAS 7440-23-5). The highest concentrations were found for elements of “little environmental concern,” including Na, potassium (K, CAS 7440-09-7), calcium (Ca, CAS 7440-70-2), and magnesium (Mg, CAS 7439-95-4).
Both the feedstock type and the procedure used to stabilize and extract PHA were observed to affect the elemental contents in the derived polymer. For example, for several environmentally relevant elements, including aluminum (Al, CAS 7429-90-5), arsenic (As, CAS 7440-38-2), cadmium (Cd, CAS 7440-43-9), iron (Fe, CAS 7439-89-6), mercury (Hg, CAS 7439-97-6), nickel (Ni, CAS 7440-02-0), lead (Pb, CAS 7439-92-1), and zinc (Zn, CAS 7440-66-6), concentrations found in PHA produced from the mixed organic fractions of municipal waste and wastewater treatment sludge were higher than in PHA produced from fruit processing wastes. However, the migrating levels were in all cases lower than the respective migration limits set by the European Toy Safety Directive or the Regulation (EU) 10/2011 on plastics intended to come into contact with food. The authors concluded that “the total content of the analyzed elements for all tested PHA types complied with the current regulations and guidelines.”
Astolfi, M.L., et al. 92020). “Elemental composition and migratability in bioplastics derived from organic waste.” Chemosphere 259: 127472.