Mental health impact of the Deepwater Horizon Oil Spill among
wives of clean-up workers
Ariane L. Rung,1 Evrim Oral,2 Elizabeth Fontham,1 Daniel J. Harrington,3 Edward J. Trapido,1
Edward S. Peters1
1
Epidemiology Program, Louisiana State University Health Sciences Center School of Public
Health, New Orleans, LA; 2Biostatistics Program, Louisiana State University Health Sciences
Center School of Public Health, New Orleans, LA; 3Environmental and Occupational Health
Sciences Program, Louisiana State University Health Sciences Center School of Public Health,
New Orleans, LA
Financial support: This research is supported by the National Institute of Environmental Health
Sciences (grant R21ES00061).
Acknowledgements: The authors wish to thank the study participants as well as the staff of the
GuLF STUDY for their assistance with subject recruitment and use of their partner data.
1
An explosion on the Deepwater Horizon drilling rig on April 20, 2010, killed 11 people and
caused almost 5 million barrels of oil to flow into the Gulf of Mexico, covering 68,000 square
miles of land and sea and triggering a response effort involving nearly 2 million gallons of
dispersant chemicals. Considered the largest accidental marine oil spill in the history of the
petroleum industry, the Deepwater Horizon Oil Spill (DWOS) resulted in widespread
environmental, economic, and population health damage, the exact nature of which is only
beginning to be understood. Research has shown that the psychological sequelae of disasters tend
to be the most pronounced, with specific psychological problems such as post-traumatic stress,
depression, and anxiety, as well as nonspecific distress, figuring prominently in the literature.1
Indeed, previous oil spill disasters have highlighted the emotional consequences to human
populations living in the vicinity and who rely on the affected areas for their economic and
nutritional livelihoods.2-4 For example, one year after the Exxon Valdez Oil Spill (EVOS) in
Alaska in 1989, higher prevalences of generalized anxiety, PTSD, and depression were observed
among residents with highest exposure.5
The Deepwater Horizon Oil Spill occurred near an area of Louisiana that had already
experienced several severe and devastating hurricanes during the previous half-decade. Early
observations of initial psychological and economic harm immediately following the DWOS6,7
have been reported, noting striking similarities between the DWOS and previous oil spills.8
Grattan and colleagues surveyed participants who were indirectly exposed through their
occupations in the fishing and recreation/tourism economies, as well as participants who were
directly exposed because spilled oil had reached the shoreline.9 Although no significant
differences in psychological distress between the two groups were found, high levels of anxiety
and depression were substantial across both groups, with greater spill-associated income loss
2
associated with greater depression, anxiety, and other mental health outcomes.9 Gill and
colleagues found that Alabama residents with greater exposure to the oil, greater economic loss,
and commercial ties to natural resources also experienced higher levels of psychological stress.8
Other Gulf Coast interviews revealed greater prevalence of depressive symptoms among
residents compared to local Behavioral Risk Factor Surveillance System (BRFSS) estimates.7
Reports of anxiety disorder, 14 or more mentally unhealthy days in the previous 30 days, and
stress about having enough money to pay for housing or food were also high.
Less is known about the mental health effects of an oil spill among specific populations,
however, particularly among women who may have been both directly and indirectly exposed to
the oil and its dispersants through their husbands who worked on oil spill clean-up efforts. As oil
spills continue to occur across the globe, research is needed to help understand the impact of
these spills and the clean-up efforts on the populations that are most closely implicated. The
Health Effects of MC252 Gulf Incident Study (hereinafter referred to as the Louisiana Gulf
Women’s Health Study, or LGWHS) is a companion study to the NIEHS Gulf Long-term
Follow-up Study (the GuLF STUDY), a health study of individuals who helped with the oil spill
clean-up. The LGWHS explores the health effects of female partners of men who participated in
the GuLF Study. The objectives of this study are to 1) describe the levels of exposure to the oil
spill among these women in southern Louisiana, and 2) describe the impact of the oil spill on the
mental health of these women.
Methods
Study Design & Population
3
The Louisiana Gulf Women’s Health Study is a cross-sectional study designed to assess the
feasibility of enrolling the wife, female head of household or significant other of male
participants enrolled in the NIEHS Gulf Long-term Follow-up Study. LGWHS participants were
recruited through male subjects of the GuLF STUDY.10 Male GuLF STUDY participants who
resided in one of seven coastal Louisiana parishes (Jefferson, Lafourche, Orleans, Plaquemines,
St. Bernard, St. Mary, or Terrebonne) were asked by NIEHS investigators to provide the name
and contact information for an adult female significant other residing in the home at the time of
the oil spill. This information was shared with the investigators of the current study. Women
were eligible to participate if they were over 18 years of age and were designated as the female
head of household, wife or significant other of an individual involved in the oil spill clean-up.
They also had to reside in our seven-parish study area at the time of the spill. Potential female
participants were sent an introductory letter describing the study and inviting them to participate.
Once a potential female subject indicated her willingness to participate, she underwent a 60minute computer-assisted telephone interview.
We received 1386 potential female subject referrals from the GuLF STUDY. Of the 1386
women, 396 (28.6%) could not be reached, 656 refused to participate (47.3%), 74 (5.3%) were
not eligible, and 8 (0.58%) began but did not complete the interview. The final sample comprised
252 women with complete interview data. The overall response rate, defined as the number of
complete interviews divided by the number of eligible women in the sample and using an
estimate of the proportion of cases of unknown eligibility that are actually eligible, was
calculated at 43%.11
4
The LGWHS was reviewed and approved by the Louisiana State University Health Sciences
Center IRB and was granted a Waiver of Documentation of Informed Consent. Participants
supplied verbal informed consent prior to initiating the telephone interview.
The telephone survey took place between November 2011 and June 2013. The survey consisted
of questions on medical, social, emotional, and behavioral domains, as well as other healthrelated questions.
Measures
Outcomes. Seven mental health outcomes were assessed. Depression was measured using the 20item Center for Epidemiological Studies Depression (CESD) Scale12 with an established cutoff
score of 16 suggestive of depressive symptoms.12-14 Serious mental illness (SMI) was measured
using the K6 instrument15,16 with scores of 13 or higher indicating probable SMI.16,17
Respondents were also asked if there had been an increase in the number of verbal or physical
fights they had had with their partner since the date of the oil spill. Two other constructs,
capturing cognitive symptoms at two points in time, were measured as well. Respondents were
asked how often they had experienced memory loss or were unable to concentrate both in the
past month and in the eight-month period following the oil spill. They were categorized into two
groups: those who responded with all of the time, most of the time or sometimes were classified
as experiencing the symptom, while those who answered rarely or never were classified as not
having the symptom.
Exposure. Exposure to the Deepwater Horizon Oil Spill was conceptualized as a multi-faceted
construct comprising both direct physical exposure to the oil or dispersants as well as indirect
economic impact from the consequences of the oil spill. The 12 questions used to assess
5
exposure were a combination of items from previous oil spill disaster research and newer items
created specifically for this study. Five yes/no items were adapted from questions used following
the Exxon Valdez Oil Spill in Alaska (Palinkas et al. 1992): a) Did you work on any of the oil
spill clean-up activities? b) Are there any other ways that you came into physical contact with the
oil from the spill or clean-up activities, such as during recreation, hunting, fishing, or other
activities? c) Did you have any property that was lost or damaged because of the oil spill or
clean-up? d) Did the oil spill cause any physical damage to the areas where you or other
household members fish commercially? e) Has the oil spill directly affected the recreational
hunting, fishing, or other activities of any members of this household?
Since it is unknown how a spouse’s exposure to the oil spill might affect a female respondent’s
health, three additional items were created from information gathered in the GuLF STUDY: a)
Did both the male index partner from the GuLF Study and his LGWH Study partner work on the
oil spill clean-up? (yes/no) b) How exposed was the male index partner to the oil? c) How
exposed was the male index partner to the dispersant? The last two items were developed for the
GuLF STUDY by industrial hygienists who estimated the amount of exposure (none, low,
medium, medium-high, and high) various clean-up jobs could engender. Participants who
reported multiple clean-up jobs were assigned the exposure level associated with their highest
exposure task. GuLF STUDY partner exposure to the oil was then classified into two groups: did
not work on the clean-up, no exposure, or low exposure vs. medium to high exposure. Partner
exposure to the dispersant was also classified into two groups: did not work on the clean-up or
unexposed vs. low to high exposure.
Three additional items were asked to measure the financial consequences of the oil spill: a) Did
you or anyone in your household lose any income due to disruption of employment or closing of
6
a business because of the oil spill? b) Compared to other residents in your community, were you
hit harder by the oil spill than others, affected about the same as others, or affected less by the oil
spill than others? This item was then dichotomized into those who were hit harder by the spill
than others vs. those who were affected about the same or less than others. c) How would you
rate the influence of the oil spill on your household’s current financial situation? Responses were
classified into two groups: those who said the oil spill had a somewhat or very negative influence
on their household finances and those who said it had a very or somewhat positive influence or
no influence on their household finances.
An index capturing the extent and frequency of respondents smelling the oil was created from
three questions asking 1) whether or not the respondent smelled any oil, 2) how strong the smell
was (5 options from not strong at all to extremely strong), and 3) how frequently it could be
smelled (5 options from none of the time to all of the time). An index was created by summing
responses about the strength and frequency of the smell, resulting in scores from 0 (did not smell
anything) to 9 (strongly smelled oil frequently).
These 12 items were combined into a single summary index, Total Exposure, whereby each
exposure endorsed above was worth 1 point with a range from 0 to 12. The index was further
subdivided into a Physical Exposure index (worked on clean-up activities, both male partner and
respondent worked on clean-up activities, male partner exposure to oil, male partner exposure to
dispersant, other physical contact, and smell index greater than 4), ranging from 0 to 6, and an
Economic Impact Exposure index (property damaged from oil spill, damage to commercial
fishing areas, recreational activities affected, income loss due to the oil spill, hit harder than
others by the oil spill, negative influence on household finances), ranging from 0 to 6. Both the
Physical and Economic Impact Exposure scores were subsequently classified into two groups
7
based on their median scores, with those falling below the median considered to be in the low to
no exposure group and those falling at the median or higher considered to be in the high
exposure group.
Covariates. Other self-reported demographic data were collected including race (White, African
American, or Multi-racial/other), education (less than high school or high school and higher),
total household income in the last year before the oil spill (less than $50,000/year or
$50,000/year or higher), current employment status (full-time, part-time, or not working outside
the home), age, marital status, industry of employment, health insurance coverage, and smoking
and drinking status. The amount of time between the date of the oil spill (April 20, 2010) and the
date of the interview was also calculated.
Statistical analyses
All statistical analyses were performed using SAS 9.4 (SAS Institute, Inc., Cary, North
Carolina). Descriptive statistics were calculated for mental health outcomes, exposure items, and
potential covariates. Logistic regression was used to estimate the associations between the Total
Exposure index and each of seven mental health outcomes. In order to assess the separate effects
of Physical and Economic Impact Exposure to the oil spill on each mental health outcome,
similar logistic regression analyses were performed. Finally, multivariable logistic regression
was conducted in which the Physical and Economic Impact exposure indices and their
interaction were included in the models as dichotomous variables to explore the joint
associations between the outcomes and exposures. All models were adjusted for race as well as
any other potential confounders that changed the crude odds ratio between the outcome and
exposure to the oil spill by more than 10%.
8
Results
Demographic characteristics
Characteristics of the study sample are described in e-Table 1. The majority of women were
white (71%), had at least a high school education (84%), earned less than $50,000/year prior to
the oil spill (58%), and were married (91%), with a mean age of 47 years (SD 12.9). Almost half
the women (45%) did not work outside the home, 47% of the women or another household
member worked in the commercial fishing industry, while 30% worked in the oil industry, and
13% worked in the hospitality/tourism industry. Over half the sample (57%) had never smoked,
while 49% had never drunk. Participants were interviewed on average 2.3 (SD 0.36) years after
the oil spill originally occurred.
Mental and behavioral health outcomes
e-Table 2 describes the mental health outcomes of the study participants. 31% of the sample
scored high (≥16) on depressive symptomatology, while 12% indicated signs of serious mental
illness. Almost a third of the women reported an increase in the number of fights with their
partner since the spill. During the 8-month period immediately following the oil spill, 32% of
participants reported memory loss all, most, or some of the time, while 43% reported an inability
to concentrate. These proportions dropped slightly to 31% and 39%, respectively, for the month
before the interview.
Exposure to the oil spill
e-Table 3 shows the distribution of exposure characteristics in the sample. The mean Total
Exposure score for the participants was 4.2 (SD 2.39), with a range of 0-12. The mean Physical
Exposure score was 1.6 (SD 1.19), with a range of 0-6. 8% of women had worked on clean-up
9
activities, and 7% worked on the clean-up and also had a partner who reported having worked on
the clean-up. 58% of these partners were classified as having medium to high exposure to the oil,
while 32% of partners were classified as having any exposure to dispersants. 44% of women
came into physical contact with the oil in other ways.
The mean Economic Impact Exposure score was 2.4 (SD 1.50), with a range of 0-5. 43% of
subjects reported the spill had caused damage to areas where they or another household member
fished commercially, 63% reported the spill had directly affected their recreational activities,
such as hunting or fishing, and 14% had property that was lost or damaged from the oil spill.
65% of subject households said they had lost income due to disruption of employment or closing
of a business because of the oil spill, while 59% felt the oil spill had had a somewhat or very
negative influence on their household’s current financial situation. Compared to others in their
community, 19% reported that they had been hit harder by the oil spill than others.
Interaction between Physical Exposure and Economic Impact Exposure
In addition to assessing the main effects of exposure to the oil spill on each mental health
outcome (see Table 1, Models 1 and 2), we explored the effect of an interaction between physical
and economic exposure on each mental health outcome. We dichotomized the Physical and
Economic Exposure variables into two groups of none/low exposure vs. high exposure and
included their interaction term into each model to assess the relationship between Physical
Exposure and each mental health outcome at different levels of Economic Impact Exposure (eTable 4, Model 3). For both depression and an inability to concentrate in the past month, there
was a significant overall interaction effect between Physical Exposure and Economic Impact
Exposure at p<0.05, while for increase in the number of partner fights, the exposures had a
borderline significant (p<0.1) overall interaction effect.
10
e-Table 5 describes the odds ratios of the interaction terms between Physical and Economic
Impact Exposures for these three outcomes. At low levels of Economic Impact Exposure, those
with high levels of Physical Exposure were 5.4 (95% CI: 2.3-13.1) times as likely to show signs
of current depression compared to those with low levels of Physical Exposure. At high levels of
Economic Impact exposure, the relationship between Physical Exposure and depression was no
longer significant.
Among those subjects reporting low levels of Physical Exposure, those with high levels of
Economic Impact Exposure were 2.7 (95% CI: 1.1-12.8) times as likely to show signs of current
depression compared to those with low levels of Economic Impact Exposure, but at high levels
of Physical Exposure, there was again no relationship between Economic Impact Exposure
current depression.
Similar patterns held with increase in number of fights and inability to concentrate in the past
month, with the exception that no relationships between Economic exposure and inability to
concentrate in the past month were seen at either level of Physical exposure. Further analyses
(not shown) revealed a lack of both positive interaction on the additive scale or the multiplicative
scale.
Discussion
The results of our study revealed 1) a high prevalence of mental health disorders, 2) a variety of
ways through which women may have been exposed to the oil spill, and 3) an association
between exposure to the oil spill and most of the mental health outcomes under study.
Prevalence of mental health disorders
11
Almost a third of our sample of female partners of male oil spill workers exhibited signs of
depression. A national sample of adults using the same instrument found the prevalence of
depression to be around 20%.13 Although not stratified by gender, 17% of men and women
exhibited signs of depression one year after the Exxon Valdez oil spill in Alaska using the
CESD.5 Depression estimates in the current study were thus not only higher than what could be
expected in the general population, but also higher than demonstrated after a previous oil spill.
Serious mental illness, as measured by the K6,15 was seen in almost 12% of our sample. National
estimates of SMI among women in 1999 from NHANES and BRFSS were 3.7% and 4.4%
respectively, while the Louisiana estimate from BRFSS for both men and women was 5.5%,18 A
comparable estimate of 15% was found in a similar local population in the year after the
DWOS.6 These data suggest that estimates of serious mental illness in the current study are
higher than national and even state averages; nonetheless, they are in line with estimates among
residents who have also experienced the consequences of the DWOS. It is not unexpected to see
such high rates of negative mental health outcomes such as depression and SMI in this particular
part of the country, given that this population has suffered repeated disasters in recent years,
including hurricanes Katrina and Rita in addition to the DWOS, likely rendering it particularly
stressed and vulnerable.
Exposure to the oil spill
Previous studies assessing relationships between exposure to oil spills and health have classified
subjects into exposure categories in one of two ways: 1) according to the community where a
subject lived, e.g., exposed communities geographically located proximal to the spill versus
similar unexposed (or less exposed) communities geographically farther from the spill2,3,9,19,20 or
2) through summed responses to questions to create a comprehensive index.3,4,21 This study
12
employed the latter approach. Because most studies using summary scores adopted different
individual items to create them, it is not possible to make direct comparisons of the various
indices used. However, there is overlap on several items. For example, 8% of our sample had
worked on actual oil spill clean-up activities, compared to 19-38% of male and female subjects
in a household survey after the EVOS.21 Gill and colleagues,8 however, reported a similar
proportion (6-8%) having worked on DWOS clean-up in their telephone survey of respondents in
South Mobile County, Alabama. Prevalence of other physical contact with oil was 44% in the
present study, though it ranged from 72% in Alaska 21 to 27% in Alabama.8 Additionally,
property loss in our study was higher (14%) than in Alaska (9%)21 and Alabama (5%),8 while
damage to commercial fishing areas (43%) was approximately the same as in Alaska (35%48%).21 Other recreational activities were affected by 63% of the current sample and only by
28%-48% of Alaska’s sample.21 Income loss due to the spill was greater in the present study
(65%) compared to another DWOS study conducted in Alabama and Florida, which ranged from
35% to 55% depending on level of exposure of the community.9 The range in exposures on these
items varies greatly across studies, likely due to the characteristics of the different populations
sampled. It should be noted that almost half our sample comprised participants from households
that worked in the commercial fishing industry, which was essentially shut down in the aftermath
of the DWOS.
Mental health and exposure to the oil spill
Because there is no accepted standardized way to measure exposure to an oil spill, it is difficult
to compare exposure across studies. The present study took advantage of the questions discussed
above as well as additional questions characterizing oil spill exposure that had not been used in
previous studies to further describe relationships between exposure and mental health. When
13
taken as an overall Total Exposure score, we observed strong relationships between increased
exposure and depression, frequency of fights with partner, memory loss and inability to
concentrate. Depression has been shown to be associated with oil spill exposure in several
studies across a variety of populations and characterizations of exposure,2-5 so the finding here
was not unexpected. However, when Total Exposure was separated into its physical and
economic impact components, depression was only associated with increased Physical Exposure.
This is contrary to findings from another DWOS study, which found an association between
income loss due to the spill and depression.9 Studies of the EVOS found no relationship between
income loss and depression.21,22 Income loss spirals, however, in which initial income loss
produces stress which increases future income loss and in turn increases future stress, were
associated with depression 6 years after the EVOS, independent of actual income loss.22 It is
possible that studies of short term (i.e., one or two years post-spill) economic effects take place
too soon to see the full impact of resource loss on mental health. Physical Exposure, on the other
hand, did exert a large influence on depression in our sample, and this was driven largely by the
effect of smell, whereby those who smelled the oil more strongly and for a longer period of time
were more likely to experience depressive symptoms (data not shown).
Fights with a domestic partner since the oil spill were a notable exception, in that Physical and
Economic Impact Exposures were both associated with an increase in the number of fights
experienced. This is supported in the literature by results from EVOS studies that found exposure
to the oil spill and subsequent clean-up efforts were significantly associated with reports of
domestic and interpersonal violence within the family.23
In our study we observe that almost a third of the sample reported some memory loss, either
currently or in the immediate aftermath of the oil spill, while inability to concentrate was
14
experienced by 39% to 43% of subjects. Both symptoms were related to Total Exposure and
Physical Exposure, while memory loss post-oil spill was also related to Economic Impact
Exposure. Mild cognitive impairment is associated with an increased risk of developing
dementia;24 as such, oil spill-associated memory loss or inability to concentrate would be
important public health concerns. Estimates of age-associated memory impairment range from
7% to 38% for older adults in the general population,24 but varying definitions and
unstandardized methodology prevent close comparisons with the current study. It must be noted,
though, that there is a strong association in our data between both cognitive symptoms and
depression (data not shown), which is not uncommon.25 Nonetheless, the finding of strong
relationships between these cognitive symptoms and exposure to the oil spill merit further
examination.
No other study to date has attempted to parse exposure into its physical and economic
components. In doing so, we attempted to isolate salient aspects of exposure related to mental
health. Of particular interest was the investigation of interaction between physical and economic
exposure. Although we found no evidence of synergy, whereby the effect of Physical Exposure
and Economic Impact Exposure would be greater than the sum of its parts, we did find some
evidence of non-homogeneity of the relationship between Physical Exposure and three of the
mental health study outcomes (depression, increase in partner fights, and inability to concentrate)
within strata of Economic Impact Exposure. Specifically, the effects of Physical Exposure on
mental health for these three outcomes were greater for those with the least economic exposure.
Limitations. This study was limited by a lack of pre-oil spill baseline data, so inferences that any
of the mental health outcomes under study are a direct result of the oil spill should be made with
caution. The cross-sectional nature of the data also precludes any causal interpretations. As time
15
elapsed since the immediate aftermath of the oil spill, it is also possible that response bias,
particularly in the form of recall bias, increased. In addition, there was no unexposed control
group; all participants came from the same communities, although detailed exposure questions
did allow us to make distinctions with regard to actual level of exposure. The study’s response
rate of 43% reflects the increasing difficulty of recruiting subjects in this already over-studied
population, although partnering with the GuLF STUDY likely made the response rate higher
than it might have been.
Conclusions. As disasters, particularly oil spills, will continue to occur, research on the mental
health impact of the Deepwater Horizon Oil spill is vital in order to sustain the ongoing
community medical response as well as prepare for the next inevitable incident. The current
study highlighted the prevalence of several mental health outcomes in this population of wives of
oil spill clean-up workers, outlined possible routes of exposure to the oil spill, and demonstrated
relationships between the mental health outcomes and oil spill exposures. However, more work
is needed to understand the multiple pathways and potential buffering influences that exist to
protect exposed residents from these repeated traumas.
16
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18
TABLES
e-Table 1. Characteristics of sample, N=252
n (%)
Race
White
175 (71.14)
African American or Black
35 (14.23)
Multi-racial/other
36 (14.63)
Hispanic ethnicity
24 (9.56)
Education
Less than high school
40 (15.87)
High school graduate
157 (62.30)
College or higher
55 (21.83)
Pre-oil spill HH income
< $20K
52 (21.76)
≥$20K-$50K
87 (36.40)
≥$50-$80K
51 (21.34)
> $80K
49 (20.50)
Marital Status
Married/living with partner
Widowed/divorced/separated/never married
230 (91.27)
22 (8.73)
Current work status
Full time
104 (43.15)
Part time
28 (11.62)
Not working outside the home
109 (45.23)
Respondent or HH member employed in commercial fishing industry
119 (47.22)
Respondent or HH member employed in oil industry
74 (29.60)
Respondent or HH member employed in hotel or tourism industry
32 (12.70)
Tobacco Use
Never smoked
143 (56.75)
Former smoker
46 (18.25)
Current smoker
63 (25.00)
Alcohol use
19
n (%)
Never drank
123 (49.00)
Former drinker
57 (22.71)
Current drinker
71 (28.29)
Age, yrs (mean ± SD)
47.1 ± 12.91
Time since oil spill, yrs (mean ± SD)
2.32 ± 0.36
e-Table 2. Prevalence of mental and behavioral health outcomes, N=252
n (%)
a
Depression
Serious mental illlness
79 (31.47)
b
29 (11.60)
Increase in number of fights with partner since oil spill
81 (32.66)
c
79 (31.47)
Memory loss in past month
Memory loss immediately post-oil spillc,d
Inability to concentrate in past month
78 (31.58)
c
Inability to concentrate immediately post-oil spill
98 (39.20)
c,d
107 (43.32)
a
Measured with CES-D, using a cut-off of 16
Measured with K6, using 13 as cut-off
c
Experienced symptom all, most, or some of the time
d
Between oil spill and Christmas 2010
b
20
e-Table 3. Measures of exposure to the oil spill
n (%)
Total Exposure (mean ± SD)
4.22 ± 2.39
Physical exposurea (mean ± SD, median)
1.61 ± 1.19, 2.0
Worked on any oil spill clean-up activities
20 (7.94)
Both partner and respondent worked on oil spill clean-up activities
17 (6.75)
Partner exposure to oil
Unexposed to oil
46 (19.49)
Low
54 (22.88)
Medium
13 (5.51)
Medium high
16 (6.78)
High
107 (45.34)
Partner exposure to dispersant
Did not work on clean-up or unexposed to dispersant
169 (67.87)
Low
62 (24.90)
Medium
0 (0.00)
Medium high
13 (5.22)
High
Extent and frequency of smelling oil
5 (2.01)
b
No smell exposure
102 (41.8)
Low smell exposure
37 (15.16)
Medium smell exposure
68 (27.87)
High smell exposure
37 (15.16)
Other ways came into physical contact with oil from the spill or cleanup activities
(e.g., during home, recreation, hunting, fishing, or other activities)
Economic impacta (mean ± SD, median)
109 (43.95)
2.42 ± 1.50, 3.0
Oil spill caused damage to areas respondent fished commercially
108 (42.86)
Oil spill directly affected recreational hunting, fishing, other activities of household
156 (63.41)
Any property lost or damaged because of the oil spill or cleanup
35 (13.94)
Respondent's household lost income because of the oil spill
163 (64.68)
Compared to others in community, respondent "hit harder by spill than others"
48 (19.28)
Oil spill had somewhat or very negative influence on household's finances
148 (58.96)
a
Physical and economic exposure scores are each based on a summation of responses to 6 items. Higher scores
indicate greater exposure to the oil spill.
b
Smell exposure is based on an index of strength and frequency of smelling the oil, where a score of 0 was
considered no exposure, 1-4 were considered low exposure, 5-6 medium exposure, and 7-9 high exposure.
21
e-Table 4. Effect estimates for each mental health outcome regressed on Physical Exposure to the oil, Economic Impact Exposure to the oil and their interaction term
Model 3
Physical Exposure
a
Depression
Serious Mental Illnessb
Increase in number of fights with partner
Memory loss past montha
a,d
Memory loss post-oil spill
Inability to concentrate past montha
c,d
Inability to concentrate post-oil spill
a
Economic Impact Exposure
p-value
Physical x Economic
N
Estimate
p-value
Estimate
Estimate
p-value
245
0.4250
**
0.0776
-0.4219
**
233
0.2525
0.1669
-0.1306
242
0.4468
**
0.5005
245
0.2609
†
0.1818
-0.1503
241
0.2886
†
0.2246
-0.0192
244
0.4784
**
0.1007
-0.2956
240
0.4135
**
0.2427
-0.1841
**
-0.3018
†
*
a
Model adjusted for race (African American, Multi/other, and White)
Model adjusted for race (White, African American, Multi/other), education (less than high school, high school or more), employment status
(full-time, part-time, not working), and smoking status (never, former, current smoker)
c
Model adjusted for race (African American, Multi/other, and White) and alcohol status (never, former, current drinker)
d
Post-oil spill refers to the 8-month window immediately following the Deepwater Horizon drilling rig explosion that occurred on April 20,
2010.
b
22
e-Table 5. Adjusted odds ratios and 95% confidence intervals for models predicting mental health outcomes with significant
interaction terms for Physical Exposure and Economic Impact Exposure
Physical Exposureb
Economic Impact
Exposureb
OR (95% CI)
OR (95% CI)
a
Depression
At low economic exposure
At high economic exposure
At low physical exposure
At high physical exposure
Increase in number of fights with partnera
5.44 (2.25, 13.14)
1.01 (0.47, 2.14)
At low economic exposure
At high economic exposure
At low physical exposure
At high physical exposure
Inability to concentrate past montha
4.47 (1.69, 11.85)
1.34 (0.65, 2.75)
At low economic exposure
At high economic exposure
At low physical exposure
At high physical exposure
4.70 (2.03, 10.89)
1.44 (0.69, 3.02)
a
2.72 (1.12, 6.61)
0.50 (0.23, 1.08)
4.98 (1.93, 12.84)
1.49 (0.69, 3.23)
2.21 (0.96, 5.12)
0.68 (0.32, 1.44)
Models adjusted for race (African American, Multi/other, and White)
b
Exposure variables categorized into two groups (no or low exposure vs. high exposure)
23