Environmental Engineering Reference
In-Depth Information
are almost exclusively man-made substances that are structurally built around rings. Each
ring is made up of six carbon atoms, but one or more rings can be linked together. Each
carbon atom can hold either a hydrogen atom or a halogen - in this case, chlorine. At that
time, we had evidence that the organochlorine chemicals shown in Table 8.1 were present
in the Arctic, but the list would later grow and eventually include substances that are not
organochlorines.
Table 8.1 Organochlorines found in the Canadian Arctic environment in the late 1980s
Pesticides
aldrin, chlordane, dichlorodiphenyltrichloroethane (DDT), dieldrin,
endrin, heptachlor, hexachlorocyclohexane (HCH), mirex and toxaphene
Industrial Chemicals
hexachlorobenzene (HCB) (also a pesticide and a by-product) and
polychlorinated biphenyls (PCBs) (also a by-product and a breakdown
product from other POPs)
By-Products
polychlorinated dibenzo-p-dioxins (dioxins) and polychlorinated
dibenzofurans (furans). Dioxins and furans can be produced naturally in
very small quantities from, for example, forest fires.
The general public had known about some of the environmental issues associated with a
number of these substances since Rachel Carson published Silent Spring in 1962. In this
very famous topic, she linked the dramatic decline of bird populations in the United States
to the intensive use of pesticides, especially DDT. Her work launched the environmental
movement in the United States. At the University of Stockholm just two years later, Sören
Jensen was trying to measure DDT in human blood using electron capture gas chromato-
graphy. He was constantly noticing another group of substances he could not identify. The
substance group was in his blood, in his hair and that of his wife and young daughter and
even in the soil outside. He was more baffled when he found the group in wildlife samples
thatweredatedbeforetheuseoforganochlorinepesticides. In1966,hesolvedtheproblem.
The mysterious substances were PCBs. It was rapidly confirmed that they were ubiquitous
in the environment. We must thank Sören Jensen for exposing just how widespread PCB
contamination had become.
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