View source for Natural sources of dioxins

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'''Natural sources of dioxins''': sources not associated with human activities. Few exhaustive analyses have been performed on old samples, but it seems on the basis of both soil samples in museums and sea and lake bottom sediment samples that pre-industrial [[PCDD/F]] levels are detectable but low. These may be due to forest fires and later due to combustion of natural items such as wood and peat. A drastic increase is seen after 1940's, and this coincides with a change in congener profiles. [[PCBs]] are not detected in pre-industrial samples.<ref> Tuomisto, Vartiainen, Tuomisto: Dioxin synopsis. Report / National Institute for Health and Welfare, ISSN 1798-0089 ; 14/2011 [http://lib.thl.fi:2345/lib4/src?PBFORMTYPE=01002&TITLEID=53321&SQS=1:FI:1::10:50::HTML&PL=0]</ref>

==References==
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[[category:Dioxin synopsis]]

[[op_fi:Luonnolliset dioksiinilähteet]]