The Republic of Korea is a maritime country surrounded by sea on three sides; the western coast of the Korean peninsula is an important route for international exchange, which has increased greatly in recent years. The risk of various kinds of marine accidents, especially major accidents, is also growing as cargo ships are getting bigger and faster. As Korea is not an oil producer and import of crude oil has been steadily increased with economic growth, the traffic of gigantic oil tankers near Korean peninsula is also increasing due to the geopolitical situation of Korea, which limits land transport of oil. After a collision of oil tankers, oil spill leads to a fast and wide spread of oil by rapid ocean currents. On December 7, 2007, the Hong Kong-registered oil tanker, the Hebei Spirit, was rammed by a crane-carrying barge of Samsung Heavy Industries tugboats. As a result, about 10,900 tons of oil spilled into sea, which contaminated 1052 km of coast and 2000 ha of beach in Taean county, Korea [1].

The oil spilled from the Hebei Spirit was reported to contain volatile organic compounds (VOCs) such as benzene, toluene, ethylbenzene, xylene (BTEX), polycystic aromatic hydrocarbons (PAHs), and heavy metals [2]. VOCs in crude oil are easily volatilized to air and absorbed into the human body through the respiratory tract, inducing irritation in respiratory system or affecting central and peripheral nervous system, while PAHs are absorbed through the respiratory tract and skin, inducing headache, nausea, and dermatitis [3]. Some components of crude oil such as benzene have been identified as carcinogenic or probably carcinogenic to humans by the International Agency for Research on Cancer (IARC) [4]. Several studies on health effects of large-scale oil spills showed development of various physical and mental symptoms in volunteers and cleanup response teams [5-7]

From the day of the accident up to July 4, 2008, the total number of participants for land cleanup was 2,122,296, and included 556,323 residents, 1,226,730 volunteers, and 152,695 military personnel [2]. In the initial stage of cleanup, several health problems were posed because most participants were not able to wear appropriate personal protective equipment such as gowns, gloves, masks, and goggles and, even worse, children were allowed to participate in the cleanup [8]. Various physical symptoms such as headache and nausea were identified through a survey of the residents and workers by the Korea Centers for Disease Control and Prevention 5 days after the disaster [9]. Military personnel were deployed in the area for cleanup activities from December 8, 2007, the next day of the disaster, and concerns have been raised about their acute health effects. The purpose of the present study was to assess physical symptoms of military personnel participated in the oil spill cleanup and the factors related to them.

This study was performed to assess acute health effects in military personnel who participated in the cleanup of the Hebei Spirit oil spill.

The present study showed that acute health effect was associated with where and how long they worked for cleanup and how well they wore personal protective equipment. The health effects of the Sea Empress oil spill were reported to be correlated with headache, nausea, eye irritation, and itchiness after adjusting for age, gender, anxiety score, smoking history, and health belief [7], and to be also significantly related to toxic symptoms such as headache, eye irritation, and sore throat due to physical exposure to crude oil [10]. Morita et al [6] reported a significant association between physical symptoms such as back pain, leg pain, headache, eye pain, and watery eye and contributing factors such as duration of cleanup and direct exposure history. A survey performed 1 month after the Erika oil spill around Brittany in France showed relationships between symptoms such as back pain, dermatitis, and headache and the duration of cleanup among the 3669 workers and volunteers [11]. Zock et al [12] indicated positive relationships between the prevalence of respiratory symptoms and amount and duration of work for cleanup in a study performed in 9050 representative fishermen 14–27 months after the Prestige oil spill. In this study, the respiratory symptoms were found to persist over a period of time; Janjua et al [5] presented a negative association between the distance from the place of oil spill and irritative symptoms on the skin, in the throat and eyes, and headache by comparing the residents who lived in the contaminated area and 2 and 20 km away from the area. Lee et al [9] found that residents in highly contaminated areas suffered from a significantly high prevalence of acute health effects such as headache, nausea, dizziness, fatigue, hot flushing, insomnia, diarrhea, sore throat, cough, rhinorrhea, dyspnea, sputum, dry mouth, itchiness, red skin, eye pain, general ache, back pain, and febrile sense compared to those in less contaminated areas [9]. Results of the present study were consistent with the results of these studies.

The level of exposure to oil may depend on personal behavior and environmental factors such as ocean currents and wind [13]. However, the present study categorized exposure levels according to their work areas: inside or outside of Taean county. For precise exposure measurements, environmental or human samples should be collected; however, it is difficult to obtain samples within hours or days after sudden disasters such as a marine oil spill, considering the volatility of VOCs and their short half-life inside the human body. Therefore, almost all previous studies have classified personal exposure levels by their places of work, with varying levels of contamination, and not by biological or toxicological tests [1].

Various components in crude oil spilled from marine accidents are known to have relatively low toxic effects because they are volatilized or vaporized and lost prior to reaching the coast [14]. Through modeling for estimating the effect of the Hebei Spirit oil spill, it was concluded that almost all VOCs in the oil were volatilized and moved along air currents [15]. The air contained various organic compounds that can act as endocrine disrupters and carcinogens, such as benzene and PAHs in high concentrations, and the oil spilled from the Hebei Spirit was relatively slowly vaporized [8]. Thus, a more active cleanup was required; the residents, volunteers, and military personnel who participated in the cleanup might have inhaled the air contaminated with the crude oil for a long period of time, which means that they were not free from their toxic effects [16].

The cleanup workers should be given appropriate protective equipment, especially gas masks with sufficient capacity to last for the first week [8]. Initial actions in response to the Hebei Spirit oil spill were blamed for inappropriate and insufficient protective equipment and lack of education regarding how to wear them [17]. Welleducated workers had used protective equipment in the correct manner and had a low prevalence of physical symptoms in case of the Prestige oil spill in Spain [18]. This finding is consistent with the result of the present study, where the workers who did not use masks properly had a higher prevalence of headache, dizziness, nausea, fatigue, sore throat, dry mouth, and rhinorrhea.

As the investigation of the present study was started 1 month after the event and, at first, the survey began with the workers of coastal area of Taean county where the level of contamination was relatively high, the recall bias might have affected their memories for acute symptoms. The design of the cross-sectional study could not be powerful enough to assess the effect of personal protective equipment. Information on the use of protective equipment during the high-exposure period, the first month after the event, was not obtained due to the late start of investigation, which is another limitation of the study and, thus, information only for the time of investigation was analyzed. The survey was conducted among military personnel only and the civilian volunteers were not compared to them in the study; therefore, the generalization of the results might be limited.

The present study demonstrated that various acute symptoms were associated with work in highly contaminated area, long duration of work, and inappropriate use of protective equipment. It should be emphasized to minimize the number of workers for early-stage cleanup, supply sufficient personal protective equipment with approved quality for blocking noxious gas, as well as provide systematic health care for the workers. Health effects could have been diminished by providing adequate education regarding appropriate use of protective equipment, especially in nonprofessionals such as residents and volunteers. To make disaster response expeditious, national and regional preparedness plans and a professional response team for emergency environmental assessment and emergency action should be established beforehand to make prompt decisions. Although the present study was limited to military personnel, it might be insufficient to support fully the long-term needs for control of health effects in the event of an oil spill. Problems regarding national actions for marine oil spills could be indicated and suggested improvements in the response system could be made based on the present study.