Pesticide Impact Rating Index
JOINT PROJECT BETWEEN
Rai Kookana, Theme Leader, Contaminant Risk Assessment and Management, Environmental Contaminants Directorate, CSIRO Land and
Water, Adelaide. and
Ray Correll and Rosalind
Miller, CSIRO Mathematics and Information Sciences,
Environmetrics
Modern
agricultural production systems need to rely on pesticides to ensure high
quality and quantity of produce. As a consequence of pesticide use, trace
levels of their residues are present in air, water and other components of
the ecosystem. This is
a cause of concern from the point of view of ecosystem and human health.
Simple but sound methods are therefore needed by pesticide users and
regulators for making an assessment of pesticide impact and choosing the
practices with the least detrimental impact on the environment.
The Pesticide Impact Ranking Index (PIRI) package, represents an
advancement over other commonly available approaches.
The approach used in PIRI
PIRI
is a First-Tier risk assessment tool developed by CSIRO for
off-site migration and impact of pesticides on water quality.
It can be used to
- rank
pesticides in terms of their relative pollution potential to
ground water or surface water
- compare
different land uses in a catchment or different industries at a
regional scale in terms of their relative impact on water quality.
In
calculating the relative pollution potential of each pesticide,
PIRI considers three
aspects, viz.
- the
value of the asset (type of water
resources threatened);
- the
source(s) of threat to the asset (pesticide use and toxic load);
and
- the
pathway through which the threat is released to the asset (runoff,
erosion, spray drift, leaching).
The detriment to the surface or ground water
in a
catchment area is calculated as the product of these three components,
i.e.
 ,
where V is the asset score, L the pesticide load and T the transport
function. Each component is quantified using pesticide characteristics
(toxicity, amount used, sorption and persistence) and soil and other site
conditions (water input, erodibility, soil loss, recharge rate, depth of
water table etc.).
For an assessment of relative impact of various
industries in a catchment or between different regions, site
specific conditions which need to be taken into consideration include size
of the industry (area), the relative value of the water body
being impacted (either in terms of its ecological significance or use for
drinking or irrigation), and the total toxic load potentially
arising from the industry.
The
software package PIRI
- provides
ratings for each pesticide’s pollution potential to surface and ground
water;
- assesses
relative impacts of different land uses in a catchment;
- serves
as an education tool and enhances awareness of the potential risk of
pesticides;
- is
user-friendly, being simple and easy to use;
- is
scientifically sound and semi-quantitative;
- considers
pesticide toxicity to fish, flea, algae and humans
- integrates
pesticide properties (toxicity, persistence in the environment,
sorption to soil), their use pattern and specific soil and site
conditions (permeability, depth of water table and water input).
- utilises
built-in data bases and requires minimum input parameters.
Where possible, sensible default values are provided to assist
the users.
- contains
a data base which includes information on a large number of pesticides
– their fate data (sorption, degradation), toxicity data (LC50 for
fish, daphnia, algae), drinking water Health Advisory Levels, and
recommended rates for pesticide use for selected land uses.
- has
been compared with the results of pesticide residue monitoring in two
intensive agricultural areas and found to be correct in more than 80%
of cases.
A help package has been designed to assist the user in all aspects of the
PIRI software package. When
used within PIRI, it automatically provides help for the active window.
PIRI was
developed by Dr. R. Kookana (CSIRO Land and Water), Dr. R. Correll and Mrs. R. Miller (CSIRO Mathematical and
Information Sciences).
Validation of PIRI:
The validation of PIRI model consisted of two case studies.
Two industries were selected on the basis of availability of good input
data on pesticide use and residue monitoring data to compare with the
output data form PIRI of both surface water and groundwater validations
In the first case study, overall, of 19 pesticides, 3 were not
consistent with PIRI predictions, showing about 84% success.
PIRI showed a similar success rate for pesticides used in the second case
study Fisher’s Exact Two-tailed test on the contingency
table of Table 3 indicated that, compared to the actual detection of a
particular pesticide, PIRI’s prediction of the likelihood of a
particular pesticide’s presence in the surface water when toxicity was
not included in the assessment was significant at the 5% level, with a probability
of 1.92%.
Offsite effects of pesticides in the Philippines and Australia:
Lysimeters are being used
as validation for groundwater movement.
Philippines Project
Stakeholders Meeting (90KB Word document)
Application of PIRI to Viticulture:
An article that was published in Australian Viticulture, Volume 6,
Number 1 (Jan/Feb 2002), pp.14-15 can be viewed or
saved in pdf format (courtesy Australian Viticulture). The
article is entitled 'An obvious question about the environment is likely
to become the obligatory question', written by Tony Clancy.
PIRI Workshops:
CMIS has held a number of workshops to
give participants hands-on experience with the PIRI package using their
own data, and learn about the PIRI concepts.
Acknowledgements:
This work has been done in collaboration with CRC for Soil and Land
Management, Land and Water Australia (formerly LWRRDC), CSIRO Land and
Water (CLW), 1CSIRO Mathematical and Information Sciences (CMIS),
ACIAR and the International Atomic Energy Agency.
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