About the List
Selection Process
The process for the 2007 Top Ten World's Worst Polluted Places is very similar to the one used last year and is intended to be logical, practical and robust. The starting point was the full database of sites nominated for Blacksmith consideration. Blacksmith staff initially screened the nominations in order to identify sites with clearly documented problems. These were then reviewed in greater detail to produce a long list of sites to be reviewed by the TAB. About half of the long list has been flagged as the most serious contenders for the Top Ten. However, any nominated site may be proposed as a contender for the Top Ten by any TAB member, based on his or her individual review.
The nomination and selection process has been refined for 2007, following a day-long TAB conference. It still remains heavily dependant on the experience and professional judgment of TAB members.
Nominations
The structure of the database of nominated sites has been upgraded and a number of new sites have been added. This brings the total number of sites in our database to nearly 400 but there remain many sites across the world that have not yet been identified. A focused effort is being put in place to expand the coverage. However, it is not expected that the database will be regarded as complete for some time yet. The 2007 World's Worst review is based on a better, but still incomplete, list of nominations.&
A key factor in this year's process is that of representative-ness. The TAB review recommended that the sites put to the full TAB for selection of the World's Worst should be representative in terms of both the types of sites in the database and also their geographical distribution. The long list has therefore been presented in the form of a matrix of candidate sites.
Scoring
The scoring system again involves an algorithm that takes into account the same basic selection criteria as last year. This approach is based on basic hazard assessment logic that can be summarized as:
IMPACT = POLLUTANT & PATHWAY & PEOPLE
Each of these essential links in the causal chain is represented by criteria that are included in the scoring methodology presented below. Details of the factors and the weights attached to them have been reviewed and revised from the 2006 version, based on the advice of the Technical Advisory Board.
REVISED CRITERIA
A. Pollutant
| Factor #A1 - Severity of Toxin | |
|---|---|
| Group A - Toxins that are not assessed as acute or systemic. e.g. organics such as toluene or xylene |
1 |
| Group B - Organics that are probable carcinogens (USEPA Class 2 and 3) or substances with some systemic toxicity. e.g. VOC's, PAHs, PCBs, air pollutants such as PM10 and PM2.5 |
2 |
| Group C - Known carcinogens or chmicals with significant systemic or organ system toxicity. e.g. vinyl chloride, benzene, lead, radionuclides, hexchromium, cadmium, organophosphate pesticides. |
3 |
| Factor #A2 - Amount or scale of pollutant source | |
|---|---|
| Limited | 1 |
| Moderate | 1.5 |
| Large | 2 |
These two factors are taken as multiplicative and so the overall score for this element is as follows:
SCORE A = A1xA2
B.Pathway
| Factor #B1 - Evidence of Human Exposure Pathway | |
|---|---|
| Clear Pathway | 1 |
| Multiple Pathways | 2 |
| Large | 2 |
| Factor #B2 - Reliable Evidence of Health Impact | |
|---|---|
| No | 0 |
| Yes | 1 |
These two factors are taken as additive and so the overall score for this element is as follows:
SCORE B = B1+B2
C. People
| Factor #C1 - Number of People Potentially Affected | |
|---|---|
| <10,000 | 1 |
| 10,000 to 100,000 | 2 |
| >100,000 | 3 |
| Factor #C2 - Level of exposure | |
|---|---|
| Low | 1 |
| Medium | 1.5 |
| High | 2 |
Factors C1 and C2 are taken as multiplicative.
| Factor #C3 - Large numbers of children particularly at risk | |
|---|---|
| No | 0 |
| Yes (e.g. play areas, schools) | 1 |
This factor is taken as additive to the other two and so the overall score for this element is as follows:
SCORE C = (C1xC2)+C3
D. Discretionary Element
| Factor #D - Additional High Risk Element (TAB member discretion) | |
|---|---|
| No | 0 |
| Yes | 1 |
On the above basis, the total score is calculated as:
SCORE = [A1xA2] + [B1+B2] + [(C1xC2)+C3] + D
On this basis, the maximum score that could be assigned to a site is 17, as follows:
SCORE = [3x2] + [2+1] + [(3x2)+1] + 1
