FARGO, N.D. — The World Health Organization (WHO) defines genetically modified organisms (GMOs) as those organisms in which the genetic material has been altered in a way that does not occur naturally.
In general terms, the safety assessment of genetically modified (GM) foods should investigate toxicity, allergenicity, specific components thought to have nutritional or toxic properties, the stability of the inserted gene, nutritional effects associated with genetic modification and any unintended effects that could result from the gene insertion. Many GM varieties of major crops such as soybeans and corn have been developed to be resistant to the use of most potent glyphosate-based herbicides (GBHs).
In response to the findings of the most recent scientific studies, the WHO’s International Agency for Research on Cancer concluded in 2015 that glyphosate is “probably carcinogenic to humans.” In response to changing use patterns of GBHs and advances in scientific understanding of their potential hazards, a group of very prominent scientists from the U.S., Canada and the United Kingdom has produced a statement of concern drawing on emerging science relevant to the safety of GBHs.
The scientists’ statement of concern considers current published literature describing GBH uses, mechanisms of action, toxicity in laboratory animals and epidemiological studies. It also examines the derivation of current human safety standards.
They conclude that:
- GBHs are the most heavily applied herbicides in the world and usage continues to rise.
- Worldwide, GBHs often contaminate drinking water sources, precipitation and air, especially in agricultural regions.
- The half-life of glyphosate in water and soil is longer than previously recognized.
- Glyphosate and its metabolites are widely present in the global soybean supply.
- Human exposures to GBHs are rising.
- Glyphosate is classified authoritatively as a probable human carcinogen.
- Regulatory estimates of tolerable daily intakes for glyphosate in the U.S. and European Union are based on outdated science.
The scientists offer many recommendations to further improve our predictive capability regarding glyphosate risks. Some of their recommendations are:
- The scientists independent of glyphosate’s registrants should conduct regulatory tests of GBHs that include glyphosate alone, as well as GBH-product formulations.
- Epidemiological studies are needed to improve knowledge at the interface of GBH uses, exposures and human-health outcomes.
- Biomonitoring studies, such as the U.S. Center for Disease Control and Prevention’s National Health and Nutrition Examination Survey program, that are examining reference populations should examine human fluids for glyphosate and its metabolites.
- More comprehensive toxicity experiments, including those using “two hit” study designs, which examine early life exposures to GBHs followed by later-life exposures to chemical or other environmental stressors, are needed.
- Because GBHs are potential endocrine disruptors, future studies should incorporate testing principles from endocrinology.
- Future studies of laboratory animals should use designs that examine the full lifespan of the experimental animal, use multiple species and strains, examine appropriate numbers of animals, and carefully avoid contaminating GBH and other pesticides in control feeds and drinking water.
- GBHs should be prioritized by the U.S. National Toxicology Program for safety investigations, including tests of glyphosate and common commercial formulations.
U.S. agriculture, and especially the production of major grains and oilseeds such as corn and soybeans, are almost exclusively GM-based. Increasing global awareness of potential excessive toxicity on humans, animals and the environment by the crops treated with GBHs may have a profound effect on global markets of these commodities.
U.S. dependence on world markets historically has been very large, thus introducing potential new risks to U.S. farmers and exporters in terms of their ability to meet the demands of evolving and health-aware international markets. Closely following further scientific developments and international health and food policies that may have an impact on the welfare of the U.S. farm sector is very important.
— Dragan Miljkovic, Professor, NDSU Agribusiness and Applied Economics Department
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