Global Trends in Ship-Sourced Marine Pollution 
13 
Causes of oil spills 
Incidents usually Involve a series of events, ultimately leading to the final outcomes Identified In Table 1. 
Table 1 provides an overview of causes of spills In each spill size category. The causes are subdivided Into 
two categories, operational (Identifying Incidents occurring mainly In ports and harbours) and accidental 
(Identifying Incidents occurring whilst the vessel Is en route). Clearly the results show that the majority of 
small spills (<7 MT) are due to operational activities, accounting for a total of 63.1% of these Incidents. Col 
lisions and groundings are the major causes of large spills, accounting for 47.9% of these Incidents In the 
7-700 MT size category and 65.4% In the > 700 MT size category respectively. Groundings make up the 
largest percentage (36.3%) as the primary cause for large spills. The other/unknown category represents 
Incidents where the cause Is not known or no Information was available. 
Categories 
% of spills 
<7 MT 
7 - 700 MT 
> 700 MT 
Operational 
Bunkering 
7.2 
2.6 
0 
Loading/discharging 
40.3 
30.7 
8.1 
Other operations 
15.6 
5 
1.1 
Accidental 
Collision 
2.2 
26.7 
29.1 
Grounding 
3 
21.2 
36.3 
Hull failure 
2.6 
4.6 
12.4 
Equipment failure 
2.6 
3.1 
0.9 
Fire & explosion 
1.1 
2.6 
7.2 
Other/unknown 
25.3 
3.5 
5 
Table 1: Percentage of tanker spills In three size categories by cause 
Trends in ITOPF attended oil spills 2000-2010 
The total number of spills ITOPF attended for the period 2000-2010 was 221. The number of tanker Inci 
dents were 83 (32%) and non tanker Incidents 129 (68%). Clearly the majority of Incidents ITOPF currently 
attends are from non tankers, however this should not be Interpreted as an Indication of performance of the 
non tanker sector. Some factors that contribute to this trend are that the non-tankers comprise the largest 
share of seaborne trade, and all spills from any ship have become Increasingly high profile events. Recog 
nising Increased public awareness of the environmental and economic Impacts of spills from ships bunkers 
and cargo.