Two different calculation models have been developed to enable trends in the health and environmental risks of plant protection products to be measured. These are PRI-Nation and PRI-Farm. Using the models, risk indicators showing trends in potential risks at national or farm level are obtained.
National risk indicators
PRI-Nation can be used to show the impact different measures have had on the risks associated with plant protection products in Sweden. Risk indicators are calculated for each active substance contained in plant protection products. There is one indicator for health risks and one for environmental risks. Updating, maintenance and reporting of PRI-Nation are dealt with by the Swedish Chemicals Agency.
Risk indicators for farms
PRI-Farm is intended to be used to measure risk trends on individual farms. Tests have been conducted on a number of farms under the direction of the Odling i Balans ("Cultivation in balance") project. Continued development work is now in progress under the auspices of the Swedish Board of Agriculture on the farm indicators.
Both models are based on the same principle, where hazard and exposure are scored and multiplied by the number of treatments. The following data are used in calculating environmental and health indicators for PRI-Nation:
For each individual active substance (approx. 270):
- Sold quantities.
- DT50lab and DT50field, half-life in soil in laboratory experiments and field trials.
- Koc, measure of the distribution of a substance between water and soil (adsorption) based on the content of organic carbon in the soil.
- Kow, partition coefficient between octanol and water.
- BCF, bioconcentration factor.
For each product (one representative product per substance):
- recommended dose,
- application method,
- application frequency,
- hazard category,
- R phrases (selected environmental and health risk phrases).
Further information on the indicator's methodology, its basis of calculation etc. can be found in KemI PM No 6/04 Pesticide Risk Indicators at National Level and Farm Level - A Swedish Approach.
The two models at present supplement one another. In the longer term it is desirable to be able to combine results from farm level so that they can also be used to describe risk trends at national level.
Results - national risk indicators
The result is presented as the annual sum of the environmental and health risk indicators of all the substances. These are then compared with the total number of hectare doses each year. The three data series are indexed with 1988 as base year (index 1988 = 100) to emphasise the relative change over time.
The number of hectare doses has continued to increase according to statistics from Statistics Sweden (SCB). Weed and fungicide preparations account for the main increase. This increase is also reflected by an increase of the environmental risk index and to a lesser extent of the health risk index. In a long-term perspective, the health and environmental risks, expressed as an index, have decreased significantly. The decrease compared with the base year 1988 is 72 and 30 per cent, respectively.
The risk indicators are based among other things on the number of hectare doses calculated from the annual quantity of each active substance sold. The sold quantity may be shifted between individual years due to hoarding activities, partly caused by pre-announced increases in tax on plant protection products. The fluctuations that can be observed in 1994/1995, 1999/2000 and 2003/2004 are examples of such occasions when sales do not reflect actual use in the same years and therefore do not reflect the risks either.
(Click to enlarge the graph)