Monitoring pesticide reduction

 in Sweden

Eighty-two percent reduction in hazard adjusted pesticide quantities 1986 - 2005

Since the mid 1980s, the pesticide reduction programmes have helped the Swedish government gain many achievements in reducing the risks from pesticide use. Wide stakeholder involvement has helped facilitate one of the most progressive pesticide policy initiatives in the world (Pesticides News). Compared to the pesticide consumption in agriculture, horticulture and forestry 1981-1985 (the official baseline period), the 2001-2005 consumption had decreased by 63 %. Calculated as hazard adjusted quantity, the reduction was 82 % (Table 1). This measure should be useful as an administrative or political tool to estimate changes in acute health hazards. Such a method could allow a better estimate of changes in potential acute health hazard caused by the substitution of relatively toxic pesticides with less toxic pesticides  (see Tables 2 and 3).    

Table 1. Pesticides used in agriculture, horticulture and forestry – A comparison of consumed quantities and hazard adjusted quantities during four 5-year periods

The ten pesticides (active substances) that contributed most to the total hazard adjusted quantity for 1981-1985, 1991-1995 and 2001-2005 are shown in Table 2.

Table 2. Top ten pesticides in terms of hazard adjusted quantities during three 5-year periods 

The WHO hazard class for each of the "top ten" pesticides in Table 2 are shown in Table 3.

Table 3. Top ten pesticides in terms of hazard adjusted quantities during three 5-year periods 

 
How to calculate hazard adjusted quantities of pesticides

 In Sweden, every manufacturer who has had a registered pesticide product filed (registered) on some occasion during a calendar year has an obligation to provide the registration authority (the Swedish Chemicals Agency) with information on the quantity sold (excluding export) before a specified date in the following year. Based on these figures, the registration authority calculates and publishes the total sales of each active substance annually. 

In 1996, the following method was used and described (1, 2) for the first time to calculate “acute toxicity equivalents” as a measure of acute health hazard and as an approximation of pesticide risk reduction. In 2001, this method was again used and a summary of the results published (3).

As a first step, a “relative toxicity factor” is calculated for each individual compound (active substance).To arrive at this factor, the LD50 value for mercuric chloride (a fungicide with LD50 (oral, rat) = 1 mg/kg body weight and selected as reference substance) is divided by the LD50 value of each individual pesticide (active substance) (4, 5, 6). 

In a second step, the relative toxicity factor is multiplied by the quantity (in tons) of each active substance (7, 8, 9, 10, 11). The number thus obtained is the acute toxicity equivalent or hazard adjusted consumption (in tons). 

References

(1) Ekström G, Hemming H, Palmborg M, Swedish Pesticide Risk Reduction 1981-1995: Food Residues, Health Hazard, and Reported Poisonings, Reviews of Environmental Contamination and Toxicology, Vol 47, 119-147, 1996

(2) Ekström G, Hemming H, Palmborg M, Swedish Pesticide Risk Reduction Achievements, Vaxtskyddsnotiser No 1, 1996, 2-7 [in Swedish with summary in English]

(3) Ekström G, Bergkvist P, Persistence pays – lower risks from pesticides in Sweden, Pesticides News No. 54, 10-11, 2001

(4) The WHO Recommended Classification of Pesticides by Hazard, and Guidelines to Classification 2004

(5) Tomlin C , Editor, The Pesticide Manual - A World Compendium, British Crop Protection Council [latest available edition]

(6) U.S. EPA Fact Sheets on New Active Ingredients

(7) Quantities of Pesticides Sold in 2001; [in Swedish with a summary in English]

(8) Quantities of Pesticides Sold in 2002; [in Swedish with a summary in English]

(9) Quantities of Pesticides Sold in 2003; [in Swedish with a summary in English]

(10) Quantities of Pesticides Sold in 2004; [in Swedish with a summary in English]

(11) Quantities of Pesticides Sold in 2005; [in Swedish with a summary in English]

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