Pesticide Risk Reduction in Ontario Crop Agriculture

Pesticide Risk Reduction in Ontario Crop Agriculture
Based on results of a study completed by G.J. Gallivan and G.A. Surgeoner, Department of Environmental Biology, University of Guelph, and J.Kovach, Cornell University

The Food Systems 2002 program, introduced by Ontario Premier David Peterson during the 1987 election, was created with the mandate of reducing provincial farm pesticide usage by 50 per cent, while "maintaining our agricultural productivity." It had three components: pesticide certification programs, the hiring of 11 integrated pest management (IPM) specialists and new money for research. The program was vague as to how the 50 per cent was to be measured, but tonnes of total active ingredient was generally assumed to be the measure.

Ontario agriculture is on target to meet this objective. Results of a survey on pesticide usage in agriculture, completed every five years by the Ontario Ministry of Agriculture, Food and Rural Affairs, show that quantity of pesticide usage in Ontario crop agriculture has decreased from 8,127 tonnes (active ingredient) in 1983, to 6,870 tonnes in 1988, to 5,812 in 1993. The 1993 figure is down 28.5 per cent from 1983. Greater reductions are expected when the 1998 survey is completed. This reduction in pesticide usage has occurred despite an increase in total provincial crop tonnage of 4.1 per cent from 1983 to 1993, and an increase in average crop yields of 16.3 per cent over the same period. (Total crop acreage decreased by 9.5 per cent over the interval, though two-thirds of this reduction involved reduced acreage of hay and pasture, neither of which entails large pesticide usage.)

The decreased pesticide usage has occurred for several reasons. These include a shift from corn to soybeans (more rotations, less use of atrazine and rootworm insecticides), increased use of newer low-rate herbicides including sulfonyl ureas compounds (see reduced pesticide use for soybeans in 1993 as an example), and the effects of programs such as mandatory certification of agricultural pesticide users, the Ontario Environmental Farm Plan program and newer pesticide formulations.

Critics of the progress being made to reduce Ontario farm pesticide use have suggested the reduction has occurred only by using pesticides which are more concentrated and "toxic" in nature. In order to test this, G.J. Gallivan and G.A. Surgeoner at the University of Guelph and J. Kovach at Cornell University analyzed the environmental impact of farm pesticide use in Ontario over the 1983-1993 period. They did this by calculating the Environmental Impact Quotient (EIQ), a scoring system for the relative risk of pesticides, developed for the IPM program at Cornell.

The EIQ is an average of three general risk categories for each pesticide: potential health risk to farm workers, potential health risks to consumers either through direct food residues or via groundwater contamination, and potential negative effects on the environment. Details of the calculations can be found in Kovach et al., "A method to measure the environmental impacts of pesticides," New York’s Food and Life Sciences Bulletin, Number 139: 1-8, 1992.

The total EIQ associated with pesticide use (i.e., EIQ values for various pesticides, multiplied by Kg of pesticide used) in Ontario declined by 16.4 per cent from 1983 to 1998, and 28.7 per cent from 1983 to 1993. These reductions are similar to the decline in total tonnes of active ingredients, indicating that current pesticides are on average no more hazardous to health and environment than products used a decade ago.

A few of the key findings – of particular interest to corn and other field crop producers – are summarized in the accompanying table.

CROP	YEAR	MILLION OF HECTARES	AVERAGE RATE (kg/ha)	TONNES OF PESTICIDE (ACTIVE)	EIQ* PER HA (X 106)	EIQ FOR ONTARIO

Corn	1983	1052	3.61	3799	98	103
	1988	858	3.01	2585	77	66
	1993	809	2.98	2412	73	59

Soybeans	1983	364	3.52	1282	90	33
	1988	518	3.28	1698	84	43
	1993	688	1.65	1137	46	32

Small Grains	1983	852	0.44	376	18	15
	1988	843	0.59	495	23	19
	1993	613	0.73	446	27	16

Provincial	1983	4162	1.95	8127	60	251

Totals	1988	3895	1.76	6870	54	210
Totals	1993	3766	1.54	5812	48	179
* Environmental Impact Quotient

In discussing their findings, the authors of the study note a dilemma caused by terms of the Food Systems 2002 program mandate. If the objective is to reduce total provincial pesticide use, then the focus should be on major field crops where the largest quantity of pesticides are applied. However, if the purpose is to minimize maximum environmental risk, then greater attention should be placed on other crops where per-hectare rates of application and the associated EIQs are much greater. For example, the authors calculated average per-hectare EIQs of 830, 702 and 286 for Ontario fruit, tobacco and vegetable production, respectively, for 1993, compared to 73, 52 and 27 for corn, soybeans, and small grains, respectively. For hay and pasture the average 1993 EIQ was 2 (up from 0.4 in 1983).

It is also worth noting that the 1993 survey came before the introduction of crops modified by biotechnology. New technology for Bt and herbicide resistant crops should substantially reduce pesticide use and the overall EIQ. And an even greater number of low dose, low EIQ herbicides continue to be used preferentially.