【Paper】
Reduction Potential for the Use of Plastic Shopping Bags based on Household Waste Analysis
Masako Fukuoka*, Harumi Koizumi* and Hiroshi Takatsuki**
* Architects, Regional Planners & Associates, Kyoto（Osaka branch Office）
** Environment Preservation Center, Kyoto University
† Correspondence should be addressed to Masako Fukuoka:
Architects, Regional Planners & Associates, Kyoto（Osaka branch Office）
（Sumitomoseimei OBP plaza Bldg. 1-4-70 Shiromi, Chuo-ku, Osaka, 540-0001 Japan）

Abstract
According to our analysis in Osaka and Neyagawa City（both of which have separate collection systems for plastic containers and packaging, and have no designated garbage bag system），72-74％ of the plastic shopping bags found in household waste are reused for waste containment. The remaining 26-28％ are disposed of as empty bags. The bags that are taken out every week（mother bags）contain even smaller plastic bags within them. The smaller bags（child bags）are used to hold smaller amounts of waste and are placed in a ‘mother bag' for collection. Sometimes child bags contain other bags（grandchild bags），which may even contain more bags（great-grandchild bags），etc. In cities where collection of plastic containers and packaging takes place, 12-14％ of all plastic shopping bags in household waste were those that had been reused as mother bags. Of 19 mother bags examined, the average mother bag contained 4.2 child bags, 1.1 grandchild bags, and 0.2 great-grandchild bags. 66％ of these minor bags were found to hold wet kitchen waste. From these results, it was estimated that the weight of plastic shopping bags in our household waste could be reduced by 53％ if their use was discouraged altogether or if bags made of thinner plastic film were used instead.

Key words: plastic shopping bag, reuse, empty bag, child bag, reducing