Bioaccumulation.
It's what's for dinner.
And lunch, and breakfast. Its danger depends a bit on whether you're flora or fauna, insect or mammal, baby or oldster -- and, of course, what you've accumulated.
But it's dangerous, and on the rise.
This musing is sparked by confirmation of something I've predicted since 2008, about how neonicotinoids (a class of insecticide that's neurotoxic to flying critters) was likely at the heart of the bee collapse that's been wiping out pollinators.
On Aug. 27:
From IOP, via EnvironmentalResearchWeb:
Honeybees, bumblebees and many other insects are being slowly poisoned to death by persistent insecticides used to protect agricultural crops. Small doses of the toxic chemicals accumulate over time, meaning that there is no safe level of exposure. That's the conclusion from recent research looking at the long-term effects of a commonly used class of insecticides....
Neonicotinoid insecticides are widely used worldwide; they work by acting on the central nervous system of the insect. The chemicals have little affinity for vertebrate nervous systems, so they are much less toxic to mammals and birds....
In the case of honeybees, up to 6000 times less insecticide was required to kill them if it was administered in multiple tiny doses over a long time period....
Right now it still isn't possible to say if neonicotinoids are the sole cause of CCD in honeybees, but it seems likely that they play a significant role. "It explains the rapid increase in CCD since 2004, which coincides with the rapid growth in worldwide use of neonicotinoids - the most widely used class of insecticides," said van der Sluijs.
The bees get slightly crazier as the substance accumulates in their little bee brains, and finally are made mad, and never return to the hive.
This is not unique to bees. All it takes is something being ingested -- usually some man-made synthetic product -- that isn't able to be handled by the body's normal handling system.
Top predators have the highest levels of these bioaccumulative substances, naturally, since they are eating everything accumulated by their prey, and their prey, and their prey.
Heavy metals, Teflon™, flame retardants, PCBs, PBDEs, pthalates, and hundreds of other chemicals bioaccumulate. Whales, bears, orcas, salmon, dolphin, tuna, hawks, eagles... all are showing dangerously high levels.
The original "bioaccumulative toxin" was DDT, which was bioaccumulating in birds. See Rachel Carson's classic Silent Spring if this is new to you.
I don't know with certainty about the role of bioaccumulation in the ongoing bat collapse, but I'd wager on some kind of bioaccumulation creating bat immune system impairment, which then lets White Nose Syndrome, from a fungus which has been found in Europe without ill effects, throw off their hibernation, when once it'd just be a nuisance. Kind of like immunosuppressed patients getting hit with "opportunistic infections" that normally would be no big deal.
So what does that mean for us? Y'know, humans, as opposed to animals?
We sometimes call it "body burden" in humans. It's increasing, of course -- heck, we're not supposed to even eat fish more than once a week, because of the methylmercury and other heavy metals -- and "body burdens" shows no sign of abating. The same chemicals found in other animals is, unsurprisingly, found in us.
Might it have something to do with the rise in autoimmune diseases in the last decades? Might we be reaching a tipping point in our own internal systems?
Scientists have identified these substances. We know they don't biodegrade. We know they bioaccumulate. We know it's affecting ecosystems. We know enough to be scared.
But our testing systems for chemicals -- and the agencies that regulate toxics -- presume that if high levels are only mildly toxic, then low levels will be nontoxic.
Which makes sense with some things -- but not with bioaccumulators.
In Europe, they tend to use the "precautionary principle" with new chemicals -- presumed guilty until proven safe.
Here in free-market America, we tend the other direction: something has to be proven unsafe to be restricted.
Innocent until proven guilty makes sense with some crimes -- but not with bioaccumulators.
We may be moving toward that Silent Spring after all.