It is difficult to objectively estimate the exposure level of
subjects in studies investigating environmental calamities
caused by accidental chemical substance leakage. Although
we measured the airborne concentrations of chlorine
gas released across the community concerned 2 h
after the accidental leakage, this was not enough to quantitatively
estimate the individual exposure levels of the
subjects. Officially confirmed exposure data was very important
to describing health effects. In unexpected community
environmental accident, timely environmental
exposure monitoring is essential to prevent and evaluate
health effects of victims. In a previous study investigating
the accidental release of hydrogen fluoride that occurred
in Gumi-si in September 2012 [36], patients’ individual exposure
levels of were not known, and the distance from
the leakage site was used as a proxy marker. The distance
from the leakage site was also used in our study as an indicator
indirectly reflecting the subjects’ exposure levels.
There were many other factors that influences the exposure
level of individual victims, such as wind direction,
exact location of victims. But, we could not collect data
about exact location of individual patient at the time of
exposure except distance from accident site. If the patient
was working in a space with all closed windows or doors,
he would be minimally affected by the chlorine exposure,
even though he was within 100 meters radius.
Another limitation of this study was that we could not
estimate the total number of exposed victims. We could
not find any formal accident report of government or
other authorities which contain information about in
total how many people were exposed. Additionally, the
leakage site was located just aside to heavy traffic road
and surrounded by many buildings, it was almost impossible
to apprehend all exposed workers.
This study also had limited evaluation of the health
effects on the non-hospitalized patients because of the
lack of pulmonary function and bronchial hyperresponsiveness
tests. In the 2 hospitalized patients, the limitations
might be that no histopathological study was conducted
for a more accurate diagnosis of RADS. Additionally, bronchial
hyperresponsiveness was examined only in case 1.
According to a follow-up study conducted on 279 residents
of adjacent areas 5 months after the accident
where chlorine gas was released in Graniteville [37], 76
of 94 subjects included in the final analysis complained
of chronic symptoms associated with chlorine exposure,
and 47 were being treated in health-care institutions.
Moreover, 44 subjects showed positive results of posttraumatic
stress disorder in the questionnaire survey. The
presence of residual symptoms in a large proportion of
subjects even after several months suggests the necessity
for follow-up observations for the subjects exposed to
chlorine gas in the present study as well.
Conclusions
The 2 patients hospitalized because of accidental chlorine
gas release in Gumi-si showed clinical progressions
corresponding to RADS. All 209 non-hospitalized patients
complained of upper airway and mucous membrane irritation
symptoms only and showed no abnormalities in clinical
laboratory tests. Patients who were closer to the
accident spot more frequently complained of symptoms
such as shortness of breath, sore throat, eye pain, itching,
dizziness, anxiety, general weakness, and fatigue. We consider
it necessary to conduct a follow-up study to determine
the long-term health effects of acute chlorine gas
exposure.