4B: Identify and Monitor Herbicide Risk Drivers

Glyphosate, the active ingredient in Roundup, is the only herbicide applied to nearly all corn and soybean fields nationwide.

According to USDA pesticide use data for 2015, corn producers applied 37 different herbicide active ingredients. Of the 37 herbicides, 24 were applied to less than 5% of national corn acres, and only 5 were sprayed on 25% or more of the national crop – acetochlor, s-metolachlor, atrazine, mesotrione, and glyphosate.

The same basic point applies to soybean herbicide use, as evident in Table 4B.1 below.

Especially for the high-volume herbicides on the market for many years, there is a huge volume of available data on use, toxicity, exposure routes and levels, and risk. These data support highly refined risk assessments and allow the identification of the most important “risk drivers” by state and crop.

The extensive data on herbicide use and risks is useful both in identifying risk-drivers and herbicides that contribute modestly, if at all to public health risks.  Note in Table 4B.1 that just 5 of the herbicides used in 2015 by corn farmers accounted for 91% of the total pounds of herbicides applied, and that 24 out of the total 38 that were applied, were sprayed on less than 5% of national acres.

In the case of soybeans, just one herbicide – glyphosate – accounted for 71% of total national herbicide pounds applied on soybeans in 2015.

Such insights will allow state and regional public health officials, the medical community, and regulators to target their efforts in ways that should reduce the time and expense entailed in reducing risk.

Risk drivers exist. Most can be identified, and those that are should be the focus of ongoing research, biomonitoring, and public health programs.

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