Subjective Health Complaints Among Workers in the Aftermath of an Oil Tank Explosion

Abstract

Health in the aftermath of a malodorous chemical explosionSubjective health complaints and post-traumatic stress symptoms among workers My midway evaluators, Ole Jakob Møllerløkken and Randi Jacobsen Bertelsen, also deserve credits; pointing out possible new aims and methods for the third paper included in the thesis. Meanwhile the unpleasant smell was continuously present in the area. AimsThe main aim of this thesis was to study long-term health effects among workers in the aftermath of a chemical explosion that emitted malodorous sulphurous compounds.The first objective was to assess whether employees in the industrial area and cleanup workers had more subjective health complaints than controls one and a half years after the oil tank explosion. The second objective was to assess whether the subjective health complaints in this group declined over a four-year period following the explosion. The third objective was to investigate whether perceived smell related to the malodorous environmental pollution was a determinant of subjective health complaints and post-traumatic stress symptoms among employed adults, when the malodorous pollution was present at the explosion site, and after pollution clean-up. Material and methodsOne and a half years after the accident, all residents living within six km to the explosion site and the whole population working in the industrial harbor area or participating in the firefighting or clean-up operation were invited to participate in a health survey including a questionnaire and a clinical examination. Inhabitants, matched by gender and age to the working population and the residents, and living 9 20-30 km away from the explosion site, were invited as controls. Of the total 1016 persons who were invited, 734 persons decided to participate (response rate 72 %).This thesis is based on sub-populations from this study.From the main cohort, the employees in the industrial area, the clean-up workers and controls were included in a cross sectional study using the Subjective HealthComplaints Inventory (SHC) in 2008. Similar data were obtained in 2012, and were analysed by a linear mixed effects model in a longitudinal study.Next, all employed adults from the main cohort were divided into high and low odour score groups based on an individual odour score that was computed as the percentage of months each participant had noticed the specific incident-related odour.Questionnaire data from the Subjective Health Complaints Inventory (SHC) and the Impact of Event Scale-Revised (IES-R), both validated instruments, were analysed using a mixed effects model in a longitudinal study involving data from when the malodorous pollution was present until three years after pollution clean-up (2008, 2010 and 2012, respectively). ResultsEmployees in the industrial area and clean-up workers reported significantly more subjective health complaints, particularly neurological symptoms, compared to controls in 2008. In the longitudinal study, subjective health complaints among employees in the industrial ar...

Odour as a determinant of persistent symptoms after a chemical explosion, a longitudinal study

“…Low levels of different sulphurous compounds, including mercaptans (methyl mercaptan: 0.006 ppm, ethyl mercaptan: 0.022 to 0.056 ppm and propyl mercaptan: 0.008 ppm), were detected in air samples from the industrial area 2–3 weeks after the incident2, 3, 4 ) . One and a half years after the explosion, both hydrogen sulphide (0.03 to higher than 2.7 ppm) and different mercaptans (methyl mercaptan: less than 0.010 to 0.61 ppm, ethyl mercaptan: less than 0.008 to 2.24 ppm, propyl mercaptan: less than 0.006 to 0.16 ppm and butyl mercaptan: less than 0.005 to 0.03 ppm) were detected in air samples taken at the top of two tanks containing sludge and wash water from tank cleaning or sludge mixed with water from the fire extinction after the explosion2, 3, 4, 5 ) .…”

“…The accident and the malodorous pollution received considerable attention in national media, emphasizing the possibility of toxic health effects due to the pollution. The sulphurous odour was continuously present, and odour intensity fluctuated only due to meteorological conditions such as wind direction and velocity, and temperature2, 3 ) . After the initial clean-up, large amounts of the pollutants were stored in tanks and big bags in the industrial harbour area.…”

“…One and a half years after the explosion, both hydrogen sulphide (0.03 to higher than 2.7 ppm) and different mercaptans (methyl mercaptan: less than 0.010 to 0.61 ppm, ethyl mercaptan: less than 0.008 to 2.24 ppm, propyl mercaptan: less than 0.006 to 0.16 ppm and butyl mercaptan: less than 0.005 to 0.03 ppm) were detected in air samples taken at the top of two tanks containing sludge and wash water from tank cleaning or sludge mixed with water from the fire extinction after the explosion2, 3, 4, 5 ) .…”

“…A cross sectional study performed when the pollution was still present found that employees and clean-up workers in the industrial area had significantly more subjective health complaints compared to controls3 ) . A longitudinal study indicated that the removal of the malodorous pollution during the study period was associated with a reduction of the subjective health complaints among the workers in the industrial area6 ) .…”

“…However, these workers still reported significantly more subjective neurological complaints compared to controls6 ) . In both studies, perception of the incidence-related smell was suggested to be of importance for the development of SHC3, 6 ) , but this possible association was not examined.…”