1. Study subjects

The study subjects were 701 adults who responded to the first survey and monitoring of health impacts in 2009 and participated in the follow-up monitoring in 2012. The first survey was conducted among 9,246 residents of Taean county from January 2009 to June 2010 by using structured questionnaires. Of these participants, 7,971 underwent blood tests for investigating their hematologic profile, liver function, and renal function. In 2012, a follow-up monitoring was conducted among 891 adults who were living in the area most polluted by the oil spill accident from February to March 2012. Residents living in Sowon-myeon, Wonbuk-myeon, Iwon-myeon, Geunheung-myeon, which were exposed to the coasts contaminated by the thick oil layer at the initial stage of the accident, were classified as highly exposed subjects to oil. Of these residents, 701 adults participated in the first survey and the clean-up work (Figure 1).

Selection process for study subjects. *Highly exposed area: the area that had seashores covered with thick crude oil in Sowon-myeon, Wonbuk-myeon, Iwon-myeon, Geunheung-myeon in the beginning of the Hebei Spirit Oil Spill accident.

This study was approved by the Dankook University Hospital Institutional Review Board (DKUH201406013-HE003).