The research team found that the beebread in 17 percent of honeybee colonies exhibited acutely high levels of pesticide exposure. The study also found that 73 percent of colonies displayed chronic pesticide exposure. According to researchers, more than 60 percent of pesticides found were accounted to surrounding farmlands and orchards that were not sprayed during the blooming season. The study's lead researcher inferred that the pesticides might be coming from other treated crops that surround the orchard. It could also be that pre-bloom sprays have accumulated in nearby flowering seeds, the lead author stated.
"Surprisingly, there is not much known about the magnitude of risk or mechanisms of pesticide exposure when honeybees are brought in to pollinate major agricultural crops. Beekeepers are very concerned about pesticides, but there's very little field data. We're trying to fill that gap in knowledge, so there's less mystery and more fact regarding this controversial topic...We found risk was attributed to many different types of pesticides. Neonicotinoids were not the whole story, but they were part of the story. Because neonicotinoids are persistent in the environment and accumulate in pollen and nectar, they are of concern. But one of our major findings is that many other pesticides contribute to risk," said study lead author Scott McArt in ScienceDaily.com.
The findings were published in the journal Scientific Reports.
A vast number of studies have long established that pesticide use and exposure result in detrimental health effects among humans. A type of pesticide called neonicotinoids, for instance, was known to affect the body's central nervous system. "These synthetic pesticide chemicals do not limit their damage to the nervous systems of insects," warns environmental scientist and lab director Mike Adams, the Health Ranger. "Via the same biochemical pathways, these same pesticide chemicals also disrupt and damage the nervous systems of humans, promoting Alzheimer's and dementia," Adams warns.
According to a report by the European Food Safety Commission (EFSA), neonicotinoid pesticides inhibit the normal development and function of the human nervous system. The toxic pesticide was also known to cause damage in brain structures and functions essential in learning and memory. As a result, EFSA’s Plant Protection Products and their Residues panel has called for a definition of standards that will indicate when developmental neurotoxicity studies can be submitted.
According to the panel, two types of neonicotinoid pesticides – acetamiprid and imidacloprid – were shown to negatively impact “the development of neurons and brain structures associated with functions such as learning and memory. It concluded that some current guidance levels for acceptable exposure to acetamiprid and imidacloprid may not be protective enough to safeguard against developmental neurotoxicity and should be reduced. These so-called toxicological reference values provide clear guidance on the level of a substance that consumers can be exposed to in the short- and long-term without an appreciable health risk.”
A 2016 review also showed that exposure to the toxic chemical was associated with adverse developmental or neurological outcomes such as autism spectrum disorder and anencephaly. The pesticide was also found to cause a congenital heart defect called Tetralogy of Fallot. Chronic neonicotinoid exposure was also associated with memory loss and finger tremor. The findings were published in the journal Environmental Health Perspectives.
Furthermore, the National Cancer Institute's Agricultural Health Study showed that farmers using toxic pesticides had higher cancer rates compared with the general population. According to the study, farming communities exhibited higher rates of multiple myeloma, soft tissue carcinoma, leukemia and non-Hodgkin lymphoma.