Introduction:Regulated medical waste (RMW) management, particularly, improper discharges of RMW from small-scale medical institutions (less than 20 sickbeds), has drawn attentions. This study investigated improper discharges of RMW containers from small clinics to analyze improper discharge mechanisms.Methods:Inspectional survey categorized improper discharges into improper sealing, container deformation, overweight, container contamination, container damaging, etc. The inspection surveys were performed from April 2018 to March 2019. In total, 2364 containers were inspected, which was equivalent to 64317 Litters in container volume and around 13.19 Mg in weight.Results:About 38% of RMW containers were categorized to improper discharges. They consist mainly of improper sealing (67.0%), container deformation (24.6%), and overweight (6.31%). It was hypothesized that frequent RMW discharges allow short interval of container discharge, which prevents clinic staff from human errors due to forgetting and might reduce improper discharges. However, the inspection results rejected this hypothesis. The survey proposes that improper discharges were likely not sporadic events, which possibly occurred in any clinics, but repeated events in certain clinics. It was also hypothesized that saving discharge cost likely induced overpacking of RMW to containers, particularly larger volume containers, and caused improper sealing, container deformation, and eventually overweight. The inspection results and statistical analyses validated this hypothesis. This study also validated one more hypothesis that large compressive force required for complete sealing might cause improper sealing. The measurement results rejected it. However, they also suggest that gender and age of clinic staff might be partially associated with improper sealing.Conclusions:Improper discharges of RMW containers seem to be non-random events. Specific clinics likely repeat improper discharges using larger volume containers. It is proposed that decreasing discharge cost induces overpacking of RMW to containers, and causes subsequent problems like container deformation.