Municipalities with IPM ordinances need a way to track progress in reducing pesticide impact over time. The metric chosen must be easy to use and understand. Ideally, it should be:
One option is to assign a rating to each pesticide product used. Other systems exist for agricultural use products (Pesticide Risk Mitigation Engine and Environmental Impact Quotient), but there is a dearth of options for urban and suburban IPM.
We leveraged Pesticide Research Institute’s pesticide databases and the San Francisco Hazard Tier Rating system to create the Pesticide Impact Index (PII) for the City of San Francisco.
Advantages of PII over EIQ
The Environmental Impact Quotient (EIQ) is a common index used to assess impact and track impact over time. Pesticide Impact Index:
The best possible estimate of impact comes from quantitative risk assessments, because they provide accurate estimates of actual exposure. The risk assessments featured were developed by the US Forest Service.
This set of risk assessments is more accurate than EIQ and PII when ranking relative impacts associated with Savana and Roundup Ultra Herbicide.
An index based on scores and summed across criteria (environmental impacts, human health impacts) may fail to capture large differences in relative risk. A score of 3 is not very different from a score of 1 in an index that sums 4 scores. We trade accuracy for administrative simplicity.
When should I use PII and when should I use EIQ to assess impact?
Impact Index in Action
The Impact Index is calculated for each pesticide application, and then summed over the year to create a representation of the change in impact over time.
These data show that San Francisco Recreation and Park Department is reducing pesticide use over time, and selecting lower toxicity products. This scenario can be compared with two hypothetical scenarios, below.
Contact PRI at firstname.lastname@example.org to see how the Pesticide Impact Index can be used to track your pesticide impacts over time!
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