Oberon,
You said "The two sources don't disagree on the facts, in that they both recognize the possible risks. The expert commentator simply disagrees that these possible risks outweigh the gains, and the 2009 study doesn't properly address that."
The panel of scientists agreed with the stockholm convention and the WHO that ddt use should be limited to only when there is no other option available. As for the risk outweighing the gains, this is up for debate at this point which is what we are doing. The argument is not whether the risk of ddt use outweighed the gains 50 years ago but if it outweighs the gains now. We have other options working now without ddt use so the panel seems correct that ddt use should only be used when there is no other option available.
You said "All your dates are talking about the 1990s. I'm not saying that deforestation doesn't have anything to do with malaria rates in the 90s and later. But it can't account for an increase of 17 to over 2 million in five years. Are you seriously suggesting that the jump from 1964 to 1969 was due to deforestation?"
I could not find specific data for deforestation rates in sri lanka during that time. However i am not just talking about the 1990s. The dates for deforestation line up almost exactly with malaria increase in most cases and in fact they seem to line up better than the ddt/ malaria link in many cases. In brazil for example.
"DDT spraying on the walls inside the houses and the use of chloroquine to treat febrile cases - succeeded in freeing the majority of the country from malaria transmission by the late 1960s/beginning of the 1970s, it was, however, unable to contain the rapid spread of the disease in the Amazon Basin, where malaria still remains a serious health problem".
Malaria Journal | Full text | Malaria in Brazil: an overview
So we see that even though ddt was used effectively in other areas of brazil it was ineffective in the exact area that deforestation occured and at the exact time a huge increase in deforestation occured.
" It was in the 1960s that deforestation in the Brazilian Amazon became more widespread, chiefly from the removal of forest to make way for cattle ranching to raise national revenue during a period of high world beef prices, to eliminate hunger and to pay off international debt obligations.[3] Extensive transportation projects, such as the Trans-Amazon Highway, were promoted in 1970, meaning that huge areas of forest would be removed for commercial purposes.
Before the 1960s, much of the forest remained intact due to the restrictions in access to the Amazon aside from partial clearing along the river banks."
Deforestation in Brazil - Wikipedia, the free encyclopedia
So we see a link between an increase in the deforestaion in the 1960s in the amazon to an increase in malaria in the amazon, despite ddt use. We also see
"the number of reported cases in the country that rose from 52 000 in 1970 to 578 000 in 1989"
Malaria Journal | Full text | Malaria in Brazil: an overview
Yet we know this wasnt related to ddt because an agricultural ban didnt happen in brazil until 1985 and it was still used for vector control until 1997.
"In Brazil, DDT was banned from agricultural use in 1985. In 1997, the Fundacao Nacional de Saude [FUNASA; National Health Foundation] also banned its use for vector control."
http://www.scielosp.org/pdf/csp/v23n12/03.pdf
However this increase in malaria appears to be linked to the exact time of an even greater deforestation in the amazon through the 1970s and 1980s.
"Slash and burn forest removal in Brazil increased dramatically in the 1970s and 1980s."
"By the late 1980s, an area the size of England, Scotland and Wales was being removed annually."
Deforestation in Brazil - Wikipedia, the free encyclopedia
We see this in other places as well such as kenya before the 1990s.
"The highlands were considered free of malaria through the 1960s, but since the 1980s malaria has been increasing "
Reemergence of Epidemic Malaria in the Highlands of Western Kenya
Yet we know ddt was not banned for agricultural use in kenya until 1986 and ddt was still allowed to be used to control malaria. So ddt did not appear to be effective at this time.
"DDT was banned for agricultural use in 1986, but is still authorised for malaria control".
The cost of hazards posed by pesticides in Kenyan export crops
But this malaria increase fits perfectly with the time frame of deforestation. Here we see a major deforestation taking place between 1981 and 1990.
"In the East African highlands, 2.9 million hectares of forest were cleared between 1981 and 1990, representing an 8% reduction in forest cover in 1 decade "
Deforestation and Malaria Transmission, Kenya | CDC EID
You said "In India malaria was nearly eradicated in the early 1960s, and its resurgence coincided with shortages of DDT (Sharma 1996)."
We are talking about a 10 year increase in malaria here, was there really a 10 year ddt shortage?
"After 1965, malaria rates in India rose gradually and consistently with a peak of 6.47 million cases in 1976 (NMEP, 1996)."
Malaria in India
However, this timeline fits nicely with a 50% mangrove deforestation in india.
"Today, mangrovesare one of the world's most threatened ecosystems, and are rapidly disappearing in many tropical countries where they were once abundant. For example, Malaysia may have lost 17% of its mangrove area between 1965 and 1985, India as much as 50% between 1963 and 1977"
http://uwacadweb.uwyo.edu/barbier/Does Economic Development Lead to Mangrove Loss.pdf
You said "The population at high to medium risk of contracting malaria in Colombia and Peru doubled between 1996 and 1997 (Roberts et al. 2000b)."
In cambodia we see major deforestation at the end of the 1997-1998.
"Despite domestic and international efforts to reform forest policy, illegal logging has escalated in Cambodia. The Cambodian Forestry Department and the holders of legal timber concessions estimate that Cambodia's forests will be commercially logged out within 3 - 5 years. During 1997 and early 1998 between 2.4 - 4.5 million m3 of logs were illegally felled, against a sustainable yield of 700,000m3."
Deforestation in Cambodian - the implications for the July 1998 elections and the country's reconstruction. | Global Witness
We then see a decrease in deforestation at the same time we see a decrease in malaria.
"While the estimated annual net rate of deforestation during the period 2002-2006 has declined to 0.5% in Cambodia"
Cambodia Signs Avoided Deforestation Carbon Agreements for Voluntary Carbon Standard Project | Pact - Building Capacity Worldwide
The decrease in deforestation occurs around the same time as a decrease in malaria rates.
"Between 1997 and 2005, the number of malaria cases decreased by 57 %"
Malaria Journal | Full text | Large-scale malaria survey in Cambodia: Novel insights on species distribution and risk factors
For peru, there again seems to be a link between deforestation and malaria rates.
"In the 1980s and 1990s extensive areas in the Andean foothills were cleared for coca plantations. Falling coca leaf prices and eradication efforts by the government cut the area under cultivation from 115,300 hectares in 1995 to 31,150 hectares in 2003."
Peru: Environmental Profile
We see an increase of deforestation in the 1990s which is in the same timeframe as an increase in malaria.
"From 1992 to 1997, malaria increased 50-fold in Loreto and fourfold in Peru."
Malaria Reemergence in the Peruvian Amazon Region
After 1998 we see a dramatic decrease in malaria which seems to be linked to the dramatic decrease in deforestation "from 115,300 hectares in 1995 to 31,150 hectares in 2003". Please see the chart on this link to see the decrease in malaria between 1998 and 2003.
http://www.paho.org/english/AD/DPC/CD/mal-cases-deaths-1998-2006.pdf
This study also discusses the link between malaria and deforestation in peru.
THE EFFECT OF DEFORESTATION ON THE HUMAN-BITING RATE OF ANOPHELES DARLINGI, THE PRIMARY VECTOR OF FALCIPARUM MALARIA IN THE PERUVIAN AMAZON -- VITTOR et al. 74 (1): 3 -- American Journal of Tropical Medicine and Hygiene