Spectacle frames: Disposal practices, biodegradability and biocompatibility – A pilot study

Background: Only limited information is available on the disposal methods for spectacle frames, and their interaction with the environment once such disposal occurs. Aim: This study investigates the disposal of spectacle frames and provides a preliminary report on their biodegradability and biocompatibility. Setting: The study was conducted at a university in the south eastern part of South Africa. Methods: The study was conducted in two parts: Part A consisted of an explorative, quantitative design using a closed-ended questionnaire investigating the current disposal methods of 375 spectacle wearers for their old spectacles; and Part B consisted of a descriptive, cross-sectional design involving chemical analyses of metal and plastic spectacle frames. Results: Almost 55% of the participants reported either keeping or reusing their spectacles. Only 5% had used a recycling method when disposing their previous spectacles. Inductively coupled plasma optical emission spectroscopy results showed that metal frames do not degrade easily unless they are oxidised in an acidic environment. Lead was detected in two metal frames. Results of thermogravimetric analysis revealed that plastic frames only begin to degrade at temperatures over 250 °C. Gas chromatography-mass spectrometry results suggest that plastic frames, except three dimensional (3-D) polarisers, are biocompatible as they are stable, not chlorinated and do not possess heavy metals. The results suggested that eco-friendly frames may be the most biocompatible. Conclusion: It appears that few spectacle wearers use recycling for disposing their frames. Current metal and plastic spectacle frames appear to have poor biodegradability but good biocompatibility.