Abstract
Previous field studies have reached no collective consensus on whether Bt corn, one of the most commonly planted transgenic crops worldwide, has significantly lower aflatoxin levels than non-Bt isolines. Aflatoxin, a mycotoxin contaminating corn and other commodities, causes liver cancer in humans and can pose severe economic losses to farmers. We found that from 2001–2016, a significant inverse correlation existed between Bt corn planting and aflatoxin-related insurance claims in the United States, when controlling for temperature and drought. Estimated benefits of aflatoxin reduction resulting from Bt corn planting are about $120 million to $167 million per year over 16 states on average. These results suggest that Bt corn use is an important strategy in reducing aflatoxin risk, with corresponding economic benefits. If the same principles hold true in other world regions, then Bt corn hybrids adapted to diverse agronomic regions may have a role in reducing aflatoxin in areas prone to high aflatoxin contamination, and where corn is a dietary staple.
Highlights
Bt corn is one of the most commonly planted transgenic crops worldwide
If any, of these aflatoxin-related cancer cases occur in the US because, among other reasons, the US Food and Drug Administration (FDA) has set meaningful action levels for allowable aflatoxin in human food and animal feed: 20 micrograms per kilogram of aflatoxin in human food (20 parts per billion, or ppb), and varying standards for livestock and poultry
In the late 1990s, it was first discovered that Bt corn had lower levels of the fungal disease Fusarium ear rot than non-Bt isolines, because it controls the insect pest European corn borer (Ostrinia nubilalis), which in turn reduces fungal infection by the endophytic fungus Fusarium verticillioides[14]
Summary
Bt corn is one of the most commonly planted transgenic crops worldwide. First produced in the United States in 1996, Bt corn contains transgenes from the soil bacterium Bacillus thuringiensis, which enable it to produce crystal proteins toxic to certain insect pests. These states were chosen based on completeness of data concerning Bt corn planting by county, aflatoxin-related insurance claims, and other factors necessary to conduct the analyses. To assess the impact of both transgenic corn and climatic factors on aflatoxin problems in US corn, we developed a model that estimates causal relationships between the risk of aflatoxin-related insurance claims and Bt corn adoption rate, drought index, and climatic variables.
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