Drs Henk Tennekes and Francisco Sanchez Bayo published this key study back in 2011 but it is vital that anyone involved in the bee deaths and neonics issue understands the KEY finding of this study. Since 1945, all pesticides were subjected to the LD50 Risk Assessment, by which scientists gradually increased the test dose fed to bees, until 50% of the bees died within 48 hours. Alternatively, they reduced the amount fed to bees until 50% survived after 48 hours. This established the LD50 dose (Lethal death 50%). BUT, two scientists discovered that if you administer a much, much smaller dose of poison, over a much longer period of time, the effect is just as deadly, but a far, far smaller total dose is need to kill half the bees. So, although a dose of 1 part per billion of clothianidin does not kill a bee in the field, such a dose will kill the entire colony if it is fed to the bees for 60 days.
Time-dependent-toxicity is absolutely crucial to understanding why bee colonies collapse when exposed to very, very small doses of neonics over long periods of time.
Moroever, many studies have confirmed that - since the entire farming landscape has been contaminated with neonics since 1994 - bees and other pollinators have been exposed to neonics - and dozens of other pesticides - at these time-dependent doses - on a daily basis for more than 20 years.
That is why the current LD50 Risk Assessment used for regulating pesticides is completely obsolete.
It can never reveal the true toxicity of time-dependent, chronic, sub-lethal poisoning.
Bee colonies are permanently contaminated with clothianidin, imidacloprid, thiamethoxam and 20 other pesticides, in the wax, in the brood food, in the pollen and nectar coming into the hive every day and in the stored pollen which may be in the hive for 6 months or more.
Source: Graham White, Environmentalist, 2 November 2016
http://www.omicsonline.org/time-dependent-toxicity-of-neonicotinoids-an…
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