There's also been confusion between federal and state agencies over
safe thresholds for the chemicals, which until recently, were not listed as hazardous substances or required for testing.
Two of the biggest aero engine makers — Rolls - Royce in the UK and General Electric in the US — did not return phone calls or emails asking for comment on if, how and when they plan to
establish safe thresholds.
Last year, James Hansen of GISS and Columbia University said that we may have already exceeded the
maximum safe threshold for CO2 in atmosphere — we're presently at approximately 387 parts - per - million (ppm) and Hansen said that we needed to target 350 ppm as the stabilization threshold, not 450 - 500 as recommended in the last IPCC assessment report.
One of the downsides of using such a cable, however, is that your device will usually charge more slowly as modern chargers use the data channels to communicate with the device and set an appropriate maximum transfer threshold (absent this communication, the charger will default to the
lowest safe threshold).
It is proof that we don't know if there is
a safe threshold and, if there is one, what it is, and as such that most bodies advise none or only minimal consumption.
However, since there is
no safe threshold to exposure to radiation, permissible does not mean safe.
«Boundaries for a Healthy Planet,» by atmospheric scientist Jonathan Foley, explains
the safe thresholds for environmental processes that profoundly affect sustainability.
«Particulate air pollution is like lead pollution, there is no evidence of
a safe threshold even at levels far below current standards, including in the rural areas we investigated,» said Schwartz.
So the questions become: What's
a safe threshold?
«Our study does not have the right design to draw conclusions on
a safe threshold of caffeine intake during pregnancy,» Papadopoulou said.
It is likely that companies that produce and sell Bentonite Clay products could claim this exemption as well, since the lead is already bonded, and it contains much less than
the safe threshold according to Prop 65.
A consumer advocacy group As You Sow did independent testing on a number of popular brands and found levels to be higher than
the safe threshold set by California (though the levels were still within the FDA's limits).
Surge protectors use a variety of different methods to do this, but they generally boil down to a system that diverts energy over
the safe threshold to a protective component in the surge protector itself.