Self-study
The water of Lake Laberge, in Canada, currently contains high levels of the pesticide toxaphene. ███████████ ███ ███████ ███████ █████████ ███ ██████ ██ █████ ███████ ██ ███ █████ █████ ███ ███ ██ ████ ████ ██ █ ███ █████ █████ ██ ███ ██████
"Surprising" Phenomenon
Why does Lake Laberge, in Canada, contain high levels of toxaphene when toxaphene was banned in North America in the 1980s and is now used only in a few other parts of the world?
Objective
The correct answer must help explain why Lake Laberge contains high levels of toxaphene even though the substance was banned in Canada in the 1980s. The correct answer will either discuss how toxaphene from the past has remained in the lake, is still being produced in or near the lake, or is being introduced to the lake from somewhere else.
1.
Which one of the following, ██ █████ ████ ████ ██ ███████ ███ ███ █████ ██ ████ ███████ █████████ ████████ ████ ██████ ██ ██████████
a
Levels of pesticides ██ ███ ███████████ █████ ████████ ██ ██ ████ ███ ███████ █████ █████ ███ █████
If (A) is true, the high levels of toxaphene currently found in Lake Laberge could just be left over from before Canada’s toxaphene ban.
b
Lake Laberge's water ████████ ████ ██████ ██ █████ ██████████ ███████ ██████████
We’re not concerned with other pesticides. We just want to know why there are high levels of toxaphene in the lake when toxaphene has been banned in Canada since the early 1980s.
c
Toxic chemicals usually ██ ███ ██████ █████ █████████ ██ ███ ███████████
It doesn’t matter how far toxic chemicals usually travel. The distance toxic chemicals travel doesn’t help explain why Lake Laberge currently contains high levels of toxaphene when the substance has been banned in Canada since the early 1980s.
d
North American manufacturers ███████ ███████ ██████████
Whether North American manufacturers supported or opposed the ban is irrelevant. We want to know why Lake Laberge contains high levels of toxaphene all these years after the ban.
e
Toxic chemicals become ████ ███████ ██████████ ████ ████ █████ █████████ ███ ████ ██ █████
The stimulus never discusses fish. It only discusses how a lake in Canada contains high levels of toxaphene even though toxaphene was banned in Canada in the early 1980s.