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<DIV>Link to the o --Apple-Mail-44-322942025 Content-Type: text/plain; charset=US-ASCII; format=flowed; delsp=yes Content-Transfer-Encoding: 7bit Hi DAve, On 20-Apr-12, at 9:09 PM, David & Alison Webster wrote: > Hi Again, Apr 20, 2012 > In my earlier post I forgot the mention that the commentary in > the top URL has some significant misinformation i.e. "Pesticides get > more concentrated as they move up the food chain..."; a half truth > and therefore a half falsehood. I don't think erecting this straw man is warranted. If you read the study itself (in the Proceedings of the Royal Society B) or the popular exposition of it in Science Now (URLs of both below) you will see that the study is confined to the effects of DDT and its metabolites, which as an organochlorine, does bioaccumulate in lipids. Thus its clear in both contexts that the use of the word "pesticide" is strictly in relation to DDT and its metabolites. So, the context makes clear: no half-truths or half-falsehoods. > Lipid-soluble pesticides are prone to bioaccumulation because > they partition into lipids and are therefore less exposed to > metabolic breakdown but even lipid-soluble pesticides require a > multistage food chain to have much effect. > > Shortly after this consequence of lipid solubility was > recognized, a great deal of effort was expended to develop > pesticides that were not prone to bioaccumulation and the earlier > lipid-soluble ones were largely retired DDT and other organochlorines were banned in 1973 in North America. However: 1. Chimney Swifts migrate through central America and the Caribbean to wintering grounds in northwestern South America and some of those jurisdictions did not ban the use of DDT until substantially later. 2. Although the amounts of DDE (a stable metabolite of DDT) in this study peaked in the late 1950's and declined until 1973 (when DDT was banned), it did not decline subsequently, indeed there was a slight (and statistically significant) rise until 1992 (when the chimney in this study was capped). Indeed this continuing persistence of DDE in the environment is still apparent in the proportions of Hemiptera/ Coleoptera in the Chimney Swift diet. Moreover, since Coleoptera are hit harder by organichlorines than are Hemiptera, and (overall) Hemiptera are at a higher tropic position in the foodchain, and they consequently bioaccumulate more DDE then do Coleoptera, so the fact that Chimney Swifts were consuming a greater proportion of Hemiptera in their diets, means they were being receiving a greater dosage of DDE. The authors point out that the reasons for the global decline of aerial insectivores remain speculative (and climate changes and other anthropogenic impacts doubtless also play a role), however this study provides a compelling (if preliminary) indication that DDT application dramatically altered insect community structures from circa 1945-1973, which triggered nutritional consequences for aerial insectivores like Chimney Swifts and that at least some of those consequences persist to the present day. Cheers! Chris http://news.sciencemag.org/sciencenow/2012/04/clues-to-species-decline-buried.html http://rspb.royalsocietypublishing.org/content/early/2012/04/15/rspb.2012.0445.full --Apple-Mail-44-322942025 Content-Type: text/html; charset=US-ASCII Content-Transfer-Encoding: quoted-printable <html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; = -webkit-line-break: after-white-space; ">Hi DAve,<div><br><div><div>On = 20-Apr-12, at 9:09 PM, David & Alison Webster wrote:</div><br = class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><span = class=3D"Apple-style-span" style=3D"border-collapse: separate; color: = rgb(0, 0, 0); font-family: 'Times New Roman'; font-style: normal; = font-variant: normal; font-weight: normal; letter-spacing: normal; = line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: = 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: = 0px; -webkit-border-horizontal-spacing: 0px; = -webkit-border-vertical-spacing: 0px; = -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: = auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div = bgcolor=3D"#ffffff"><div><font size=3D"2">Hi Again, = Apr 20, = 2012</font></div><div><font size=3D"2"> In my earlier = post I forgot the mention that the commentary in the top URL has some = significant misinformation i.e. "Pesticides get more concentrated as = they move up the food chain..."; a half truth and therefore a half = falsehood.</font></div></div></span></blockquote><div><br></div><div>I = don't think erecting this straw man is warranted. If you read the study = itself (in the Proceedings of the Royal Society B) or the popular = exposition of it in Science Now (URLs of both below) you will see that = the study is confined to the effects of DDT and its metabolites, which = as an organochlorine, does bioaccumulate in lipids. Thus its clear in = both contexts that the use of the word "pesticide" is strictly in = relation to DDT and its metabolites. So, the context makes clear: no = half-truths or half-falsehoods.</div><br><blockquote type=3D"cite"><span = class=3D"Apple-style-span" style=3D"border-collapse: separate; color: = rgb(0, 0, 0); font-family: 'Times New Roman'; font-style: normal; = font-variant: normal; font-weight: normal; letter-spacing: normal; = line-height: normal; orphans: 2; text-align: -webkit-auto; text-indent: = 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: = 0px; -webkit-border-horizontal-spacing: 0px; = -webkit-border-vertical-spacing: 0px; = -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: = auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div = bgcolor=3D"#ffffff"><div><font size=3D"2"> <span = class=3D"Apple-converted-space"> </span><strong>Lipid-soluble</strong= ><span class=3D"Apple-converted-space"> </span>pesticides are prone = to bioaccumulation because they partition into lipids and are = therefore less exposed to metabolic breakdown but = even l