Industrial manganese pollution causes debilitating manic behavior in bees

(NaturalNews) Honeybees exposed to levels of manganese formerly assumed to be safe exhibited modified behavior, premature aging and cognitive disruption, according to a study conducted by researchers from Washington University and Macquarie University in Australia, and published in the journal Biology Letters on March 24.

"We've known for a long time that high doses of manganese kill neurons that produce dopamine, causing a Parkinsonian-like disease in people," researcher Yehuda Ben-Shahar, PhD, said. "In insects, as well, high levels of manganese kill dopaminergic neurons, reducing levels of dopamine in the brain.

"But in this study we were looking at low-level exposure and we saw the opposite effect. Instead of reducing dopamine levels, manganese increased them. Increases in dopamine and related neurotransmitters probably explain some of the abnormal behavior."

Bees act older, disoriented

Manganese is an essential trace nutrient that helps mediate cellular reactions and remove toxic byproducts of oxidation. Yet at higher levels, it is toxic.

"We evolved in an environment where there was little manganese, and so we developed ways to pump it into our cells," Ben-Shahar said. "But now environmental levels are quite different from those to which we are adapted and we don't really know what that means for human health."

The new study into manganese and honeybees began as a study by the Washington University researchers into the way bees respond to sugar, a trait that changes as bees age. That's because for the first few weeks of life, adult bees care for young bees in the hive; for the rest of their lives (a few weeks more), they forage outside the hive and therefore need to be more responsive to food sources.

Prior studies had shown that sugar response in bees is suppressed by a specific gene, which causes cells to take up more manganese. In 2004, Ben-Shahar and colleagues found that this gene and higher levels of manganese also played a role in the age-related changes in bees' sugar responses.

Because manganese has been shown to interfere with dopamine pathways related to motor function, Ben-Shahar wondered if it might also affect the pathways related to pleasurable behaviors, such as eating. To measure tiny fluctuations in dopamine levels, the Washington State researchers partnered with Macquarie University researcher Andrew Barron.

The researchers then fed different levels of manganese to bees and fruit flies, and tracked their activity patterns. In both species, levels of manganese equivalent to those considered safe for human food led to increases in the neurotransmitters dopamine and octopamine. Slightly higher levels of manganese increased dopamine levels further, causing the bees to begin foraging earlier in their lives but make fewer foraging trips overall. Evidence suggests that the bees were more likely to become tired or disoriented.

Other metals also damage the brain

The findings underscore the dangers posed by even trace levels of toxic metals.

"When we try to understand pathologies, we often look at extremes," Ben-Shahar said. "We tend to ignore more modulatory changes like this one and assume we don't need to worry about them. But that may be a mistake. The bees, which vacuum up everything in the environment, might be serving as an early warning indicator of an environmental toxin."

Manganese is just one of many metals shown to be toxic to the human brain; the most infamous are lead and mercury. Indeed, it is mercury's well-known neurotoxicity that has led to the ongoing concern over its presence in vaccines, including flu shots still given to children.

Because heavy metals are used in manufacturing such a wide range of industrial products, they can be found almost everywhere, from electronics and other household goods to air pollution and even the sewage sludge that is eventually spread on food crops.

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