Environmental impact assessment of chlorine in liquid crystal display glass (LCDG) based on material flow analysis

Liquid crystal display glass (LCDG) may contain chlorine in trace amounts to attain some of its special properties. LCDG is primarily manufactured by glass companies, which then supply the electronic industry for utilization in the manufacture of items such as televisions, computer monitors, etc. In order to be seen as environmentally friendly, some electronic companies that utilize LCDG request that glass companies eliminate halogens such as chlorine from LCDG. The issue of halogens in products is often associated with dioxin-like problems. By using halogen-free LCDG in their manufacturing process, electronic companies aim to enhance their eco-friendly branding. Nevertheless, the real gains in terms of environmental improvement are yet to be assessed. In this study, we discussed the effectiveness of reducing or eliminating chlorine in electrical and electronic products on a scientific basis, by carrying out a quantitative assessment of cancer risk posed by potential emissions of dioxins when discarded LCDG is incinerated. The results indicate that the maximum increase of individual lifetime cancer risk is 3.2 × 10−10. This level of cancer risk is negligible. Consequently, we suggest that there is no need to introduce stricter standards for chlorine content in LCDG, from the viewpoint of potential dioxin formation.

► Incineration of liquid crystal display glass (LCDG) may generate dioxins. ► We estimated the amount of discarded LCDG in Japan based on material flow analysis. ► Discarded LCDG might increase from 1800 to 23,000 tons/year from 1998 to 2045. ► We estimated cancer risk, assuming exposure to dioxins from incineration of LCDG. ► The risk is negligible at both present and future rates of LCDG incineration.