A new report by the United Nations Environment Program says that crops such as wheat and maize could produce toxins as a reaction to extreme weather, making them dangerous for humans and animals.

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A new (UNEP) warned that rising global temperatures have the potential to trigger common grain crops (such asbarley, maize and wheat) to generate harmful toxins. The UN agency's dossier observed that extreme heat conditions could likely induce plants to create chemical compounds in an attempt to safeguard themselves. The report explained that drought "slows or prevents" nitrate conversion in crops, which would prompt nitrate to build up to dangerous levels, making them toxic for humans and animals to consume.

"Crops are responding to drought conditions and increases in temperature just like humans do when faced with a stressful situation,” Jacqueline McGlade, UNEP's chief scientist.

"We are just beginning to recognize the magnitude of toxin related issues confronting farmers in developing countries of the tropics and sub-tropics," the report added. "As warmer climate zones expand towards the poles, countries in more temperate regions are facing new threats."

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Camilo Mora, a professor at the University of Hawaii who studies crop ecology, told weather.com in an email that UNEP's advisory was backed up by previous research.

"There are indeed several recent scientific papers, (suggesting) biochemical changes in crops due to climate changes," Mora said. "Prior studies have identified a reduction in the nutrient content of crops under climate change, this new study suggests a new mechanism for the accumulation of compounds that are toxic to people. Although certainly novel, many of these responses are not surprising. Species have evolved to live under very specific set of climatic conditions, so one can expect all sorts of changes in species as we continue to change our climate. That is the sad reality of adaptation to climate change...something has to give up."

Stephen Long, a crop scientist at theUniversity of Illinois, told weather.com in an email that there were remedies available to assuage potentially poisoned crops, but that UNEP's concerns were overblown.

"I can agree with a little of this report, but some is rather clearly hype and there are simple technologies to avoid others," Long said. "We also have direct evidence of the opposite in soy, where growth under future CO2 causes a down-regulation of some of the secondary metabolic pathways, with the result of great insect damage."

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