ANALYSIS OF OIL SPILL TRENDS
IN THE UNITED STATES AND WORLDWIDE
Dagmar Schmidt Etkin
Environmental Research Consulting
750 Main Street
Winchester, Massachusetts 01890
ABSTRACT: This presentation examines trends in U.S. oil
spillage, with respect to historical and current trends in the
United States and worldwide, and analyzes potential influences
on spill frequencies. Contrary to popular perceptions, the numbers of oil spills, as well as the amount spilled, have decreased
significantly over the last two decades, particularly in the last few
years despite overall increases in oil transport. Decreases are
pronounced for vessels. U.S. pipelines now spill considerably
more than tankers. Overall, U.S. oil spillage decreased 228%
since the 1970s and 154% since the 1980s. This decrease mirrors
international trends and can likely be attributed to reduced
accident rates, due to preventive measures and increased concerns over escalating financial liabilities.
xylene, ethylene, and toluene), or liquefied natural or petroleum
gas. “Facilities” include oil terminals, storage tanks, refineries,
industrial facilities, utilities, and other stationary sources with the
exception of pipelines.
U.S. oil spill trends
Vessels. Oil spills from vessels in U.S. waters have followed a
pattern of increase from 1985 through 1993, followed by a decline from 1993–1995, and gradual increase from 1995–1999.
Vessels other than tankers and barges that carry oil as cargo drive
much of this trend (Figure 1). Tanker and barge spills decreased
during 1985–1999, with a particularly significant drop since 1990
(Etkin, 2000a). The number of spills from tankers and barges in
1999 was only 12% the number in 1990. Much of this decrease
can be attributed the decrease in oil transport by tankers and
barges through U.S. waters over the last several years. At the
same time, freight transport has increased somewhat, increasing
the likelihood of spills from freighters. Overall, oil movement to
and from the United States has increased by over 42% since
1988.
Spills from tankers and barges comprise only 13% of the total
annual spill number, but, since the largest vessel spills tend to be
from oil cargo vessels, 78% of the volume of oil spilled from
vessels comes from tankers and barges (Figure 2). Barge spills
have exceeded tanker spills in number and amount spilled. Since
1990, the average barge spill has been larger than the average
tanker spill, and barges overall have spilled more than tankers
(except for 1997) (Etkin, 2000a).
The frequency distribution of spill size classes shows that spills
under 100 gallons represent 92% of the total spill number, but
only about 1% of the total spill volume from vessels (Figure 3).
The total volume from spills of less than 100,000 gallons has not
changed appreciably since 1985, with spills of at least 100,000
gallons contributing the most to annual fluctuations of total vessel
spillage (Figure 4). Tanker spills show similar trends to barge
spills over the last 15 years (Figure 5), as is the case when the
spills in the different size classes are analyzed as a percentage of
the total spill number. Both tankers and barges show no appreciable change in frequency of the largest size classes, an apparent
decrease in spills of 100–999 gallons (0.34–3.4 t), and an increase
in the percentage in the 1- to 9-gallon size class.
The smallest size classes usually are associated with bunkering, lightering, and loading, or to structural and equipment failures not attributable to accidents. This generally holds true for
barges, tankers, and freight vessels (Etkin, 2000a). Freighters
Methodology
Oil spill data used in this study are from the Environmental
Research Consulting Spill Databases, which collate data from a
large number of sources and databases, including information
from the U.S. Coast Guard (USCG), U.S. National Response
Center (NRC), U.S. Environmental Protection Agency (EPA),
U.S. Office of Pipeline Safety (OPS), U.S. Minerals Management
Service (MMS), various U.S. state databases, Environment Canada, Oil Spill Intelligence Report, International Maritime Organization, International Tanker Owners Pollution Federation, Tanker
Advisory Center, and other national and regional environmental
agencies. On a continuously updated basis, the data are crosschecked and corrected with current information and new information on past events. U.S. data are subject to reporting errors,
occasional duplications of records of events, and other anomalies.
Worldwide data largely reflect trends in reporting, both over time
and on a regional basis, and should be treated as underestimates,
particularly for smaller-sized spill events (under 100,000 gallons
or 340 t), for spills from regions where reporting is compromised
for political or logistical reasons, and for spills from nonvessel
sources.
An “oil spill” is defined as discrete event in which oil is discharged through neglect, by accident, or with intent over a relatively short time. It does not include an event in which oil leaks
slowly over a long period of time, nor does it include operational
spillages allowed by international or national regulations (such as
MARPOL discharges from tankers) or that occur over a relatively
long period of time (such as >5 ppm oil discharges in refinery
effluents) even if those discharges violate pollution regulations.
“Oil” is defined as a petroleum-derived substance as defined in
MARPOL Annex I, and does not include BTEX (benzene,
1291
1292
2001 INTERNATIONAL OIL SPILL CONFERENCE
6,000
All Other Vessels
5,000
Total Barge+Tanker
Number of Spills
4,000
3,000
2,000
1,000
0
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 1. Annual number of oil spills (1 gallon and over) from vessels in U.S. waters: Barges and tankers versus other vessels
(1985–1999) (Environmental Research Consulting Database).
1 4 ,0 0 0 ,0 0 0
1 2 ,0 0 0 ,0 0 0
1 0 ,0 0 0 ,0 0 0
8 ,0 0 0 ,0 0 0
Gallons
B a rg e s a n d T a n k e rs
A ll O th e r V e s s e ls
6 ,0 0 0 ,0 0 0
4 ,0 0 0 ,0 0 0
2 ,0 0 0 ,0 0 0
0
1 98 5
198 6
19 87
19 88
19 89
1 990
1 991
1 99 2
199 3
1 99 4
199 5
19 96
19 97
19 98
1 999
Figure 2. Annual amount of oil spilled by vessels in U.S. waters in spills of 1 gallon and over (1985–1999) (Environmental
Research Consulting Database).
100
1 0 0 .0
90
9 6 .5
Cum . % Num ber
C u m . % A m t.
9 9 .8
9 8 .9
9 0 .6
80
7 6 .7
70
% Total
60
50
4 8 .5
40
3 3 .5
30
20
2 5 .2
8 .4
10
0 .0
0 .1
0 .0
1 .9
0 .4
0
10000000
1000000
100000
10000
1000
100
10
1
S p ill S iz e ( G a llo n s )
Figure 3. Cumulative percentage of total oil spillage (number of spills and amounts) by size class: U.S. vessel spills (1985–
1999) (Environmental Research Consulting Database).
1 4 , 0 0 0 ,0 0 0
1 2 , 0 0 0 ,0 0 0
1 0 , 0 0 0 ,0 0 0
8 , 0 0 0 ,0 0 0
Gallons
S p il ls > 1 0 0 , 0 0 0 G a l lo n s
S p il ls < 1 0 0 , 0 0 0 G a l lo n s
6 , 0 0 0 ,0 0 0
4 , 0 0 0 ,0 0 0
2 , 0 0 0 ,0 0 0
0
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 4. Total amount of oil spilled from vessels into U.S. waters (1985–1999) spill amounts from spills over and under
100,000 gallons (Environmental Research Consulting Database).
RESPONSE ISSUES
1293
180
160
1000000 gal
100000 gal
10000 gal
1000 gal
100 gal
10 gal
1 gal
140
Number of Spills
120
100
80
60
40
20
0
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 5. Annual Number of Tanker Oil Spills In US Waters By Spill Size Class (1985-1999) (Environmental Research
Consulting Database)
tend to have lower overall spill sizes, since the oil originates from
fuel tanks and machinery spaces rather than from cargo holds.
Accidents and errors during bunkering, lightering, and loading
caused 57% of tanker spills, 71% of barge spills, and 53% of
freighter spills.
The largest vessel spills arise from accidents involving tankers,
and occasionally barges, carrying large amounts of oil cargo. The
actual number of tanker accidents (allisions, collisions, and
groundings) has decreased to about 30 per year since reaching a
peak of nearly 180 accidents in 1990 (Etkin, 2000a), undoubtedly
contributing to the decrease in tanker spillage. Annually, only
0.2% of the more than 41,000 tanker transits result in accidents,
and of these accidents less than 2% result in oil spills. The spill
rate for tanker accidents has decreased since 1990, likely due to
improved safety regulations and tanker construction. The percentage of tanker accidents resulting in oil spills of 1 gallon or
more decreased sharply since 1990 (Etkin, 2000a).
Land-based facility spills. Spills impacting U.S. marine and
navigable waterways and originating from fixed facilities (not
pipelines) have decreased dramatically since peaking in 1991
(Figure 6), following a pattern similar to vessel spills. The total
amount spilled is dominated by a tiny fraction (0.05%) of the spill
number that represents spills of 100,000 gallons or more (Figure
7). Water-impacting facility spills follow the same frequency
distribution pattern as vessel spills. The smallest spill size classes
represent a large fraction of the spill number but only a small
fraction of the total spill amount. Spills of over 100 gallons, while
representing only 8.46% of the spill number, make up over 98%
of the amount of oil spilled between 1987 and 1999.
Spills from U.S. land-based sources (pipelines, storage facilities, fixed industrial facilities, air transport facilities, railways,
and motor vehicles) not impacting marine and navigable waterways decreased by 56% in the last 6 years (Figures 8–10) to an
average of 4,800 spills of one gallon or more annually. These
4 ,5 0 0
4 ,0 0 0
3 ,5 0 0
Number of Spills
3 ,0 0 0
2 ,5 0 0
2 ,0 0 0
1 ,5 0 0
1 ,0 0 0
500
0
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1997
1999
Figure 6. Annual number of facility spills of 1 gallon and over (excluding pipelines) impacting U.S. waters (1985–1999) (USCG
data with analysis by Environmental Research Consulting).
3 ,0 0 0 , 0 0 0
S p il ls > 1 0 0 ,0 0 0 G a llo n s
S p il ls < 1 0 0 ,0 0 0 G a llo n s
2 ,5 0 0 , 0 0 0
Gallons
2 ,0 0 0 , 0 0 0
1 ,5 0 0 , 0 0 0
1 ,0 0 0 , 0 0 0
5 0 0 ,0 0 0
0
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1997
1999
Figure 7. Annual amount of oil spilled from facilities (excluding pipelines) into U.S. waters (1985–1999) (USCG data with
analysis by Environmental Research Consulting).
1294
2001 INTERNATIONAL OIL SPILL CONFERENCE
8 ,0 0 0
7 ,5 0 0
Number of Spills
7 ,0 0 0
6 ,5 0 0
6 ,0 0 0
5 ,5 0 0
5 ,0 0 0
4 ,5 0 0
4 ,0 0 0
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 8. Total annual number of U.S. land-based oil spills of 1 gallon or more (1987–1999) (EPA data with analysis by
Environmental Research Consulting).
2 5 , 0 0 0 ,0 0 0
2 0 , 0 0 0 ,0 0 0
Gallons
1 5 , 0 0 0 ,0 0 0
1 0 , 0 0 0 ,0 0 0
5 , 0 0 0 ,0 0 0
0
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 9. Total amount of oil spilled onto land in the United States in spills of 1 gallon or more (1987–1999) (EPA data with
analysis by Environmental Research Consulting).
14,000,000
AIR TRANSPORT
12,000,000
HIGHWAY
RAILWAY
STORAGE TANK
10,000,000
PIPELINE
Gallons
FIXED FACILITY
8,000,000
6,000,000
4,000,000
2,000,000
0
1987 1988
1989 1990
1991 1992
1993 1994
1995 1996
1997 1998
1999
Figure 10. Annual amount of oil spilled onto land in the United States by source type (1987–1999) (EPA data with analysis by
Environmental Research Consulting).
spills contribute over 9 million gallons of oil to U.S. land and
groundwater resources each year. Fixed and storage facilities, and
pipelines, make up the bulk of this spillage. Most of this input is
from a small number of spills of at least 100,000 gallons (Figure
11). Spills of at least 100 gallons represent 47% of spill number
and 99.6% of total spill volume. Spills of 1,000 gallons and over
represent 16% of spill number and 97% of spill volume.
Pipelines. Since 1985, U.S. pipelines have spilled more oil
than tankers and barges combined. Since 1991, pipelines have
annually spilled 37 times as much as tankers. The change in the
proportion U.S. pipeline spillage is largely due to the fact that
since 1990, pipelines transport more oil across more miles than
water carriers (Figure 12) though the actual pipeline mileage has
not increased appreciably. U.S. pipelines now carry 69.3% of oil
transported, compared to 30.3% carried by vessels (tankers and
barges). The annual number of pipeline spills has decreased by
500% over the last 30 years (Figure 13). Spill amounts are dominated by a small number of large events. Over 74% of pipeline
spills involve 100 gallons or less, while spills in these smaller
size classes contribute only 0.8% of the total amount spilled. 90%
of spills are under 1,000 gallons. Overall, the amount spilled has
decreased (Figure 14).
RESPONSE ISSUES
1295
3 0 ,0 0 0 ,0 0 0
2 5 ,0 0 0 ,0 0 0
2 0 ,0 0 0 ,0 0 0
S p ills > 1 0 0 ,0 0 0 G a llo n s
Gallons
S p ills < 1 0 0 ,0 0 0 G a llo n s
1 5 ,0 0 0 ,0 0 0
1 0 ,0 0 0 ,0 0 0
5 ,0 0 0 ,0 0 0
0
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 11. Total annual oil spillage onto land in the United States: Spills over and under 100,000 gallons (EPA data with
analysis by Environmental Research Consulting).
700
Billion Ton-Miles
600
500
400
300
Pipelines
200
W ater carriers
100
97
19
95
96
19
94
19
19
92
93
19
91
19
90
19
88
89
19
19
87
19
19
19
86
85
84
19
19
82
83
19
81
19
80
19
79
19
78
19
19
77
76
19
19
19
75
0
Figure 12. U.S. oil transport by pipelines and water carriers (1975–1999) (Bureau of Transportation Statistics data with
analysis by Environmental Research Consulting).
600
500
Number of Spills
400
300
200
100
19
98
19
96
19
94
19
92
19
90
19
88
19
86
19
84
19
82
19
80
19
78
19
76
19
74
19
72
19
70
19
68
0
Figure 13. Number of oil transport pipeline spills in United States (1968–1999) (Environmental Research Consulting
Database).
70 ,0 00,00 0
60 ,0 00,00 0
50 ,0 00,00 0
Gallons
40 ,0 00,00 0
30 ,0 00,00 0
20 ,0 00,00 0
10 ,0 00,00 0
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971
1970
1969
1968
0
Figure 14. Amount of oil spilled from U.S. oil transport pipelines (1968–1999) (Environmental Research Consulting Database).
1296
2001 INTERNATIONAL OIL SPILL CONFERENCE
Structural failures are the most common cause of U.S. pipeline
spills, representing 40% of spills. 75% of structural failure is
attributed to corrosion, 15% to defective pipes, and 10% to defective welds. With an aging pipeline infrastructure in the United
States—46% of pipelines are over 30 years old, 16% are over 50
years old, and over 2% are over 70 years old—more spills caused
by structural failure may be expected in the future. “Outside force
damage”—ramming by bulldozers or other equipment or natural
damage from floods or earthquakes—cause 27% of spills.
Offshore spills. While 98% of U.S. pipeline spills occur onto
land, occasional spills (less than 10 per year) from nearshore and
offshore pipelines contribute to marine oil input (Figure 15).
Spills from Outer Continental Shelf (OCS) exploration and production (E&P) facilities have also decreased significantly since
U.S. offshore E&P activities began (Figure 16). Nearly 94% are
spills of less than 50 barrels (2,100 gallons). On average, 80% of
OSC spills are from platforms as opposed to OCS pipelines (Figure 17). Total OCS spillage has averaged 200,000 gallons per
year, much of this is due to a small number of very large spills
(Figure 18).
Overall 1990s oil spillage in the United States. Overall U.S.
spill amounts for 1990–1999 are shown in Figure 19. The total
amount spilled in the 1990s was 134 million gallons, a significant
decrease from the previous two decades where 305 million gallons and 206 million gallons of oil spilled (Figure 20). Most of
the oil spilled in the 1990s came from fixed facilities and land
pipelines. Vessels contributed only 15%. OCS E&P facilities
contributed only 1.4% of the total oil spillage.
Worldwide oil spill trends
Reductions in U.S. oil spillage largely mirror international
trends (Figures 21–22). Spill numbers and amounts have decreased since 1990, though very large spills can skew oil
amounts. The decrease is encouraging in light of a 46% increase
in oil movement worldwide since 1988. Data presented (Figure
23–25) are underestimates for both numbers and amounts, since
data collected on an international basis are subject to serious reporting errors and omissions, particularly for spills from particular regions, for smaller spills, and for spills from non-vessel
sources. For example, vessel spills receiving media coverage
because of their high-profile location or particular circumstances
are more likely to be reflected than smaller pipeline spills in remote areas.
Assuming spills internationally follow similar patterns of spill
size frequency distributions to U.S. spills, spills of at least 10,000
gallons represent 90% of the amount spilled, but only 5% of the
actual numbers of spills. This logic was applied in analyzing the
data shown in Figure 26. International estimates for the amount
spilled and spill number in marine waters were derived by estimating the number of spills under 10,000 gallons and the
amounts spilled in those size classes based on size class frequency distributions for more well-documented U.S. spill data
sets (based on the methodology in Etkin, 1998a, 1999).
8 0 0 ,0 0 0
7 0 0 ,0 0 0
6 0 0 ,0 0 0
Gallons
5 0 0 ,0 0 0
4 0 0 ,0 0 0
3 0 0 ,0 0 0
2 0 0 ,0 0 0
1 0 0 ,0 0 0
0
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Figure 15. Annual amount of oil spilled into U.S. waters by marine pipelines (1986–1999) (Office of Pipeline Safety data with
analysis by Environmental Research Consulting).
300
250
Number of Spills
200
TO TAL
T O T A L < 1 -5 0 b b l)
T O T A L (> 5 0 b b l )
150
100
-0 .7 0
y = 3 2 7 .8 0 x
2
R = 0 .8 2
50
19
99
19
97
19
95
19
93
19
91
19
89
19
87
19
85
19
83
19
81
19
79
19
77
19
75
19
73
19
71
0
Figure 16. Annual number of oil spills from U.S. OCS exploration and production facilities (1971–1999) (MMS data with
analysis by Environmental Research Consulting).
RESPONSE ISSUES
1297
2 50
Number of Spills
2 00
P latfo rm
P ipe lin e
1 50
1 00
50
9
19
9
19
9
7
5
3
19
9
19
9
1
9
19
9
7
19
8
19
8
3
5
19
8
19
8
19
8
1
9
7
19
7
5
19
7
19
7
19
7
19
7
1
3
0
Figure 17. Annual number of U.S. OCS platform and pipeline spills (1971–1999) (MMS data with analysis by Environmental
Research Consulting).
1 , 0 0 0 ,0 0 0
Gallons
8 0 0 ,0 0 0
6 0 0 ,0 0 0
4 0 0 ,0 0 0
2 0 0 ,0 0 0
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971
0
Figure 18. Total annual spillage from U.S. OCS facilities (1971–1999) (MMS data with analysis by Environmental Research
Consulting).
Marine Pipelines
1.0%
OCS E&P
1.4%
Marine Facilities
6.2%
Tankers
5.0%
Barges
5.9%
Other Vessels
4.2%
Land Pipelines
22.4%
Storage Tanks
10.0%
Air Transport Facilities
0.4%
Unknown Land
Facilities
7.3%
Fixed Land Facilities
30.3%
Railroad
2.2%
Highway
3.7%
Figure 19. Sources of U.S. oil spillage (amount spilled from 1990–1999) (Environmental Research Consulting Database).
1 4 0 ,0 0 0 ,0 0 0
T a n k e rs
P ip e lin e s
F a c ilitie s
B a rg e s
E&P
N o n -T a n k V e s s e ls
O th e r
1 2 0 ,0 0 0 ,0 0 0
Gallons
1 0 0 ,0 0 0 ,0 0 0
8 0 ,0 0 0 ,0 0 0
6 0 ,0 0 0 ,0 0 0
4 0 ,0 0 0 ,0 0 0
2 0 ,0 0 0 ,0 0 0
0
1960s
1970s
1980s
Figure 20. Estimated annual amount of oil spilled in the United States by source (Environmental Research Consulting
Database).
1298
2001 INTERNATIONAL OIL SPILL CONFERENCE
450
400
350
Number of Spills
300
250
200
150
100
50
19
98
19
96
19
94
19
92
19
90
19
88
19
86
19
82
19
84
19
78
19
80
19
76
19
74
19
72
19
70
19
68
0
Figure 21. Annual number of oil spills of 10,000 gallons (34 tons) or more worldwide (1968–1999) (Environmental Research
Consulting Database).
4 5 0 , 0 0 0 ,0 0 0
4 0 0 , 0 0 0 ,0 0 0
3 5 0 , 0 0 0 ,0 0 0
Gallons
3 0 0 , 0 0 0 ,0 0 0
2 5 0 , 0 0 0 ,0 0 0
2 0 0 , 0 0 0 ,0 0 0
1 5 0 , 0 0 0 ,0 0 0
1 0 0 , 0 0 0 ,0 0 0
5 0 , 0 0 0 ,0 0 0
98
19
96
19
94
19
92
19
90
19
88
19
86
84
19
19
80
82
19
19
78
76
19
19
72
70
74
19
19
19
19
68
0
Figure 22. Annual amount of oil spilled worldwide (1968–1999) (Environmental Research Consulting Database).
E&P
1 2 .8 %
F a c ilitie s
7 .9 %
U n k n o w n /O th e r
0 .1 %
P ip e lin e s
4 .2 %
N o n -T a n k V e s s e ls
0 .2 %
T a n k e rs
7 4 .2 %
B a rg e s
0 .6 %
Figure 23. Estimated total amount of oil spilled into marine waters worldwide (1970–1979). Total amount spilled:
1,465,500,000 gallons (4,985,000 tons) (Environmental Research Consulting Database).
E&P
11.6%
Unknown/Other
0.2%
Tankers
33.6%
Barges
0.8%
Facilities
34.2%
Pipelines
18.2%
Non-Tank Vessels
1.4%
Figure 24. Estimated total amount of oil spilled into marine waters worldwide (1980–1989). Total amount spilled: 844,970,000
gallons (2,874,000 tons) (Environmental Research Consulting Database).
RESPONSE ISSUES
1299
Unknown/Other
0.5%
E&P
21.4%
Facilities
12.4%
Tankers
57.2%
Pipelines
6.4%
Non-Tank Vessels
1.7%
Barges
0.3%
Figure 25. Estimated total amount of oil spilled into marine waters worldwide (1990–1999). Total amount spilled: 943,170,000
gallons (3,208,000 tons) (Environmental Research Consulting Database).
1000
900
800
Million Gallons
700
1 9 7 0 -1 9 7 9
600
1 9 8 0 -1 9 8 9
1 9 9 0 -1 9 9 9
500
400
300
200
100
0
T a n k e rs
B arg es
N o n -T a n k
V e s s e ls
P i p e li n e s
F a c i li t i e s
E&P
Figure 26. Estimated total oil spill amounts by source type (Environmental Research Consulting Database).
Worldwide, tanker spills dominated the oil spill picture until
the 1990s when large pipeline and facility spills occurred. The
percentage of oil contributed by tanker spills has decreased from
74% in the 1970s to 34% in the 1990s. Extremely large spills,
such as the 1991 Gulf War spills and the 1979 Ixtoc I well blowout, and large tanker spills in the 1970s, dominate spill amounts.
Discussion
Contrary to popular perceptions after recent catastrophic
events, oil spill frequencies and total spillage have decreased
significantly over the 20 years, particularly in the last few years,
despite overall increases in oil movement. The decrease in oil
spills worldwide, but in the United States in particular, may be
attributed to a variety of influences. The impacts and repercussions of the 1989 Exxon Valdez spill, largely the impetus for passage of the Oil Pollution of 1990 (OPA 90), were watched
worldwide. With OPA 90, the United States has the strictest
tanker regulations. Improved safety standards, contingency planning, exercise programs, and other measures have helped reduce
U.S. spillage. International conventions and national legislation
have reduced worldwide oil spillage.
Much of this reduction, however, was realized before the implementation of OPA 90 and other regulations and conventions.
Another important influence on spillage rates has been realization
by tankers owners and other potential spillers that spills in the
United States could result in astronomical costs for which the
spiller could have unlimited liability (a result of OPA 90).
Cleanup, penalty, and damage costs associated with the Exxon
Valdez spill and other significant events in its aftermath have
seriously raised the stakes for potential oil spillers. Cleanup costs
have risen dramatically in the last two decades even when corrected to current values (Etkin, 1998b, c). Implementation of
pending increases in environmental damage liability nationally or
as part of international liability and compensation conventions,
along with increases in oil spill damage liability and penalties
(Etkin, 2000b) for all spill sources, could change the oil spill
picture on a worldwide basis.
While the statistics show encouraging downward trends, there
is no room for complacency. An ill-timed oil spill that occurs in a
sensitive location, regardless of spill size, can cause devastating
damage to natural environments, property, and business, and,
occasionally, to human lives. Aging pipeline and facility infrastructures, as well as aging vessel fleets, may be “ticking time
bombs” especially as they become subjected to increasing oil
throughput and transport in future years. Increased international
attention to tanker safety has had a positive influence that is
sorely needed in other vessel categories and for nonvessel
sources, particularly pipelines.
Biography
Dagmar Schmidt Etkin received A.M. and Ph.D. degrees from
Harvard University. Her environmental science experience includes: 12 years investigating population biology and ecology,
and 11 years specializing in oil/chemical spill database development, data analysis, risk assessment, and cost analyses, most recently in her own independent consulting firm, Environmental
Research Consulting.
1300
2001 INTERNATIONAL OIL SPILL CONFERENCE
References
1.
2.
3.
Etkin, D.S. 1998a. Factors in the Dispersant Use Decision-Making Process: Historical Overview and Look
to the Future. Proceedings, Twenty-First Arctic and Marine Oilspill Program (AMOP) Technical Seminar. Environment Canada, Ottawa, Ontario. pp. 281–304.
Etkin, D.S. 1998b. Financial Costs of Oil Spills in the
United States. Cutter Information Corp., Arlington, MA.
Etkin, D.S. 1998c. Oil Input Into the Marine Environment: Accidental Releases From Vessels, Pipelines, Exploration & Production Activities, Facilities, and Un-
4.
5.
6.
known Sources. Report to Joint Group of Experts on the
Scientific Aspects of Marine Protection (GESAMP)
Working Group 32: Oil Input Into the Marine Environment, November 1998.
Etkin, D.S. 1999. Marine Oil Spills Worldwide: All
Sources. Cutter Information Corp., Arlington, MA.
Etkin, D.S. 2000a. A Worldwide Review of Oil Spill Fines
and Penalties. Environmental Research Consulting, Winchester, MA.
Etkin, D.S. 2000b. US Vessel Spills 1985–1999: A
Statistical Review. Environmental Research Consulting,
Winchester, MA.