Acute Health Evects of the Sea Empress Oil Spill
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306 J Epidemiol Community Health 1999;53:306–310 J Epidemiol Community Health: first published as 10.1136/jech.53.5.306 on 1 May 1999. Downloaded from Acute health eVects of the Sea Empress oil spill Ronan A Lyons, J Mark F Temple, Daphne Evans, David L Fone, Stephen R Palmer Abstract lowed by increases in physical and psychologi- Study objective—To investigate whether cal symptoms in the general population. We residents in the vicinity of the Sea Em- undertook a population based retrospective press tanker spill suVered an increase in cohort study to assess the acute physical and self reported physical and psychological psychological health impact on the exposed symptoms, which might be attributable to population. exposure to crude oil. Design—Retrospective cohort study; postal questionnaire including demo- Methods This study was commissioned four weeks after graphic details, a symptom checklist, the incident. The exposed group was defined as beliefs about health eVects of oil and the people living on the most exposed south coast Hospital Anxiety and Depression and of Pembrokeshire (Milford Haven, Pembroke SF-36 mental health scales. Dock, Tenby, and Saundersfoot) and the Setting—Populations living in four coastal control group as similar but unexposed popu- towns on the exposed south Pembroke- lations living on the north coast (Aberaeron shire coast and two control towns on the and Fishguard) (fig 1). unexposed north coast. Sample size calculations were based on the Patients—539 exposed and 550 unexposed prevalence of symptoms in the control group people sampled at random from the reported in the Braer study.2 A sample of 814 family health services authority age-sex in both exposed and control areas was register who completed questionnaires. required for 80 per cent power to detect a Main results—Adjusted odds ratios for statistically significant (p<0.05) doubling of self reported physical symptoms; scores prevalence of symptoms in the exposed group on the Hospital Anxiety and Depression against a background prevalence of 3 per cent. and SF-36 mental health scales, in 1089 To allow for non-response, random samples of people who responded out of a possible 1000 adults (of both sexes aged 18 to 65 years 1585 (69%). old) were selected from each of the exposed Conclusions—Living in areas exposed to and control areas using the Dyfed-Powys the crude oil spillage was significantly family health services authority age-sex associated with higher anxiety and de- register. pression scores, worse mental health; and A questionnaire, with a retrospective health self reported headache (odds ratio = 2.35, diary covering the four weeks immediately after 95% CI 1.56, 3.55), sore eyes (odds ratio = the incident, was devised that also incorporated http://jech.bmj.com/ 1.96, 95% CI 1.06, 3.62), and sore throat a symptom check list used in the Braer (odds ratio = 1.70, 95% CI 1.12, 2.60) after investigation,2 the Hospital Anxiety and De- adjusting for age, sex, smoking status, pression Scale (HAD),3 the mental health pro- anxiety, and the belief that oil had affected file of the SF364 as well as a series of questions health. People living in exposed areas relating to beliefs about the eVects of the oil Iechyd Morgannwg reported higher rates of physical and psy- spill on the environment, employment, health, Health chological symptoms than control areas. and finances. The HAD Scale is widely used in RALyons on September 25, 2021 by guest. Protected copyright. Symptoms significantly associated with clinical settings and was included in the study Gwent Health exposure after adjustment for anxiety and because of the marked excess of cases of clini- Authority health beliefs were those expected from cally relevant anxiety and depression after the JMFTemple the known toxicological eVect of oil, Exxon Valdez oil spill.2 The SF-36 mental DLFone suggesting a direct health eVect on the health scale was included as population norma- tive baseline data of SF-36 health scores was University of Wales exposed population. Swansea (J Epidemiol Community Health 1999;53:306–310) available from the Pembrokeshire health status 5 D Evans study undertaken in 1994 in randomly sam- pled adults from North (n=659) and South Welsh Combined On the evening of the 15 February 1996, the Pembrokeshire (n=597). Centres for Public Sea Empress laden with more than 130 000 Questionnaires were mailed to people on the Health tonnes of light crude oil, ran aground on rocks S R Palmer 4 April (seven weeks after the grounding of the at the entrance of Milford Haven harbour in tanker). Non-responders were sent a second Correspondence to: south west Wales. Over the next week an questionnaire one month later. Non- Professor S R Palmer, Welsh estimated 72 000 tonnes of crude oil and responders to the second questionnaire were Combined Centres for 360 tonnes of heavy fuel oil were released into Public Health, University of contacted by telephone or visited at home by Wales College of Medicine, the sea, contaminating around 200 km of two of us (MT and DE) between 21 May and Abton House Wedal Road, coastline (fig 1) and causing strong smells and 18 June. CardiV CF4 6QX. complaints of symptoms from residents of the Statistical analysis was carried out using 6 7 Accepted for publication coastal towns. Similar oil spills from the SPSS for Windows and Epi Info Logistic. 19 October 1998 tankers Exxon Valdez1 and Braer2 were fol- Crude odds ratios for each self reported Acute health eVects of the Sea Empress oil spill 307 J Epidemiol Community Health: first published as 10.1136/jech.53.5.306 on 1 May 1999. Downloaded from N ★ Aberaeron ★ Fishguard Milford Haven Saundersfoot Tenby Pembroke Dock Legend Oiled shoreline 0 10 20 ★ Control towns Kilometres Study towns Figure 1 South west Wales showing extent of oil pollution and locations of study and control towns. symptom in the exposed group were calculated Results with 95 per cent confidence intervals. Other After excluding those who were positively con- categorical data were analysed using the ÷2 test firmed as not resident at their home address and continuous or ordinal data using either the during the relevant period (211 and 204 people t test or non-parametric analysis of variance as in control and exposed populations respec- http://jech.bmj.com/ appropriate. We carried out a forwards logistic tively), the overall response rate was 1089 of regression analysis for each symptom in turn as 1585 (69%), with no significant diVerence the dependent variable, adjusting firstly for between the exposed areas 68% (539 of 796) age, sex, HAD anxiety score, exposed/control and control areas 70% (550 of 789). There was status and smoking status, and secondly, no diVerence in mean age (exposed mean age including the health belief eVect variable. The 40.3 years, control 40.6, range 18–65) or the 7 female to male ratios (both 5.5: 4.5) between Hosmer-Lemeshow goodness of fit test was on September 25, 2021 by guest. Protected copyright. used to assess the eVect of inclusion of the the two groups. The reported prevalence of interaction term between anxiety and health “ever smokers” (six months or more) was higher in the exposed area (245 of 539: belief eVect in each model. Inspection of the (45.5%) 206 of 550 (37.5%) in the control data showed substantially high rates of re- v area ÷2 7.186 p = 0.0074), with no significant ported illness in the exposed population on day diVerence for current smoking ((28.2%) v one (16 February) (32 of 539 and 6 of 550 in (25.3%), p = 0.28). exposed and control areas respectively). We In the population resident in the exposed considered this most likely represented biased area, responders reported excess symptoms recall, and therefore logistic regression analysis and non-specific illness on the days when oil was undertaken after exclusion of those exposure was at its highest. Figure 2 demon- subjects. strates this for all self reported illness. The oil The dates of exposure to oil were estimated came ashore within the Haven by 17 February, from the Sea Empress Environmental Evalua- but did no approach the western shoreline of tion Committee’s Report.8 Carmarthen Bay until 22 February. The oil To estimate the impact of the oil on self persisted in the western Camarthen Bay until reported illness in the exposed population the after the study period. In the Haven area daily expected rate of illness was calculated from the rates of reported headache peaked on 16 Feb- control population. The observed minus the ruary, the day after the initial oil spill, and 23 expected was plotted for the two groups of February, one to two days after the major exposed populations. secondary spill. 308 Lyons, Temple,Evans, et al J Epidemiol Community Health: first published as 10.1136/jech.53.5.306 on 1 May 1999. Downloaded from 120 Oiling of West Camarthen bay starts 100 Initial grounding and oil loss West Camarthen bay (Tenby and Saundersfoot) 80 60 Haven 40 (Milford Haven and Pembroke dock) Observed-expected self reported illness 20 Heavy oiling of Haven starts 0 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 1 2 3 4 5 6 7 8 9 10 11 12 13 Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Feb Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar Mar 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 96 Date Figure 2 Excess (observed-expected) of self reported illness in area exposed to oil from Sea Express.