Archive for Earth Sciences Forum This site is dedicated to the Earth Sciences. We are here for you to discuss issues regarding any aspect of the Earth sciences, at all levels of knowledge. Questions are welcomed, as are open scientific debates. Enjoy!!!
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Latecommer
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DDT - hazard or benifitAccording to various estimates, a million people a year are killed by Malaria transmitted by mosquitos. At present there is no more effective way to control this hazard than DDT.
www.cdc.gov/malaria/impact/index#ref12
Why are we not using DDt? according to J. Gordon Edwards and Steven Milloy, it is because DDT has been and still is being demagoged out of use.
www.junkscience.com/ddtfaq
According to their research there has been no science that shows the DDT is the hazard we have been let to believe. DDT has actually been fed to lab animals with NO indue effects. Their conclusion is that it is not a harmful substance when properly used, and the warnings in Carson's "Silent Spring" are false.
(I see that the first cited source leads to a dead end, but if you google "Deaths due to Malaria", you can find numerous collaborating sources.)
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scpg02
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I totally agree. I can pull articles if I have to.
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Mk
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| scpg02 wrote: | | I totally agree. I can pull articles if I have to. |
Same here.
More and more and more DDT was being used, because mosquitoes were developing a resistance to the DDT. It was cheap, completely safe to use and even ingest, and due to these facts, you could use brute force.
DDT is claimed to biomagnify up the food chain, and carcinogenic and tetragenic effects start to show only with massive concentrations.
Would those concentrations would be high enough?
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Baywax
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more study required (surprise)Here's what some people are saying.
| Quote: | Health risks and benefits of bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT).
Rogan WJ, Chen A.
Epidemiology Branch, US National Institute of Environmental Health Sciences, P O Box 12233, Research Triangle Park, NC 27709, USA. rogan@niehs.nih.gov
DDT (bis[4-chlorophenyl]-1,1,1-trichloroethane) is a persistent insecticide that was used worldwide from the mid 1940s until its ban in the USA and other countries in the 1970s. When a global ban on DDT was proposed in 2001, several countries in sub-Saharan Africa claimed that DDT was still needed as a cheap and effective means for vector control. Although DDT is generally not toxic to human beings and was banned mainly for ecological reasons, subsequent research has shown that exposure to DDT at amounts that would be needed in malaria control might cause preterm birth and early weaning, abrogating the benefit of reducing infant mortality from malaria. Historically, DDT has had mixed success in Africa; only the countries that are able to find and devote substantial resources towards malaria control have made major advances. DDT might be useful in controlling malaria, but the evidence of its adverse effects on human health needs appropriate research on whether it achieves a favourable balance of risk versus benefit.
PMID: 16125595 [PubMed - indexed for MEDLINE] |
http://www.ncbi.nlm.nih.gov/sites...d=Retrieve&list_uids=16125595
Carcinogen and Neurotoxin, Immunotoxin
| Quote: | At the Palos Verdes Shelf, large deposits of DDT and PCBs sit in the sediments deep underwater. The chemicals came from area industries, including a large DDT manufacturing facility, Montrose
Chemical Company, which closed in 1982.
High levels of DDT and PCBs off the coast of Los Angeles led the Federal and State of California governments (now working together under the Montrose Settlements Restoration Program) to file
suit against the polluters in 1990, with EPA joining the suit soon after. The State of California issued advisories in 1991 to caution people about possible health risks of eating certain fish in the area.
The EPA Superfund program initiated actions to address the Palos Verdes Shelf site in 1997.
The EPA and the Montrose Settlement Restoration Program work closely together on projects related to DDT and PCB contamination in the area, with the EPA focusing on site investigation and
human health and ecological risk reduction. The Montrose Settlements Restoration Program focuses on projects to restore natural resources - such as fish habitat and birds - affected by the
contaminants, as well as projects to educate anglers and the general public about healthier alternatives to the more contaminated fish.
DDT is considered a probable human carcinogen, and can cause liver, reproductive and nervous system damage. PCBs have been demonstrated to cause a variety of adverse health effects,
including impact on the immune, reproductive, nervous systems. |
http://www.webwire.com/ViewPressRel.asp?aId=44336
DDT's effects on ecology
| Quote: | Effect of p,p'-DDT on rumen ecology, EKG patterns, and respiratory rate of beef steers.
Rumsey TS, Slyter LL, Shepherd SM, Kern DL.
PMID: 5487105 [PubMed - indexed for MEDLINE] |
http://www.ncbi.nlm.nih.gov/sites/entrez
and
| Quote: | Effects of DDT treatments applied for tsetse fly control on White-headed Black Chat (Thamnolaea arnoti) populations in Zimbabwe. Part I: population changes
R. J. Douthwaite1
(1) Tsetse and Trypanosomiasis Control Branch, PO Box 8283, Causeway, Zimbabwe
(2) Natural Resources Institute, Central Avenue, Chatham Maritime, ME4 4TB Chatham, UK
Received: 7 December 1991 Accepted: 28 January 1992
Abstract Surveys of relative abundance were made in DDT-treated and untreated woodland in NW Zimbabwe using playback of tape recorded song. Chats were common in old stands of untreated mopane (Colophospermum mopane) and miombo (Brachystegia spp.) woodland but were less common in suitable habitat which had been sprayed with DDT at the rate of about 200 g ha–1 for tsetse fly control. Population changes in the Siabuwa Communal Area were related to spraying operations over 3.5 years from July 1987 to January 1991. In the 1987–89 treatment area, numbers fell by 88% over 33 months following first treatment, mainly due to a reduction in occupied sites. Groups were smaller and single sex groups more frequent in treated areas compared with an adjacent unsprayed area. Numbers in the unsprayed area fell by 13% over the same period. Total numbers and number of groups at the edge and just within the treated area increased temporarily after each of the first two sprays. At the end of the study, numbers in the 1987 and 1987–89 treatment areas were increasing, and isolated groups were found in the 1984–89 treatment area. In a second study area, a further treatment of DDT, one year after the first, was followed by a 74% decline in numbers over nine months. It is concluded that tsetse spraying operations have had a severe, and possibly prolonged, impact on the White-headed Black Chat population of NW Zimbabwe. |
from: http://www.webwire.com/ViewPressRel.asp?aId=44336
| Quote: | | DDT is toxic to many types of aquatic organisms, even at low concentrations. |
from
http://www.epa.gov/region5superfund/ecology/html/toxprofiles.htm
The list goes on. We just finished reviving the Bald Eagle population after the effects of DDT began diminishing that population and now everyone wants to fall back on this antiquated and toxic method of killing mosquitos (and everything else?)
Is it a good idea to wipe out our ecological support system to create a temporary lull in deaths caused by Malaria?. Once the mosquitos are "controlled" there will be famine, drought and accumulated Dioxins, PBCs and DDT to kill us.
Rather than relying on the methods of the 1940s, can someone please come up with a better idea? Netting has reduced deaths due to Malaria by a significant amount.
| Quote: | Insecticide treated nets: impact on vector populations and relevance
of initial intensity of transmission and pyrethroid resistance
C.F. Curtisa*, B. Jana-Karab & C.A. Maxwellc
aLondon School of Hygiene & Tropical Medicine, London, U.K., chris.curtis
Insecticide treated bednets locate a deposit of a quick-acting insecticide of low human toxicity between a sleeper and host-seeking mosquitoes. Thus a chemical barrier is added to the often incomplete physical barrier provided by the net. Treated nets may be considered as mosquito traps baited by the odour of the sleeper. Trials in Assam, Tanzania and elsewhere have shown that when a whole community is provided with treated nets, so many mosquitoes of anthropophilic species are killed by contact with the nets that the density and/or sporozoite rate of the vector population is reduced. In order to gain this “mass” or community effect, in addition to widespread personal protection, and thus to achieve the full potential of the treated net method, a high per cent coverage of the community is needed.
This suggests that organised free provision of treated nets, comparable to a house spraying programme, is likely to be more cost-effective than trying to market nets and insecticide to very poor rural people. In areas with high malaria transmission, where acquisition of immunity to malaria is very important, it has been argued that vector control (without vector eradication) could, in the long run, make the situation worse by preventing the normal build-up of immunity. However, our data from Tanzania do not support this idea—3–4 years after provision of nets (which are re-treated annually) young children are still showing clear health benefits; older children are not “paying” for this by showing worse impact of malaria. There is less malaria morbidity in a highland area where malaria transmission is about 15x less intense than in a nearby lowland area. The per cent impact of treated nets malaria morbidity in both areas was very similar. At present only pyrethroids are used for net treatment which suggested that emergence of pyrethroid resistance would have a disastrous effect. However, in West Africa, where there is now a high frequency of the kdr resistance gene in Anopheles gambiae, it is reported that treated nets continue to have a powerful impact on vector populations. In Tanzania, pyrethroid resistance has not been detected in malaria vectors, but it has emerged in bedbugs after seven years use of treated nets. |
http://www.malariaconsortium.org/data/files/pages/net_1.pdf
This seems like an slightly less, overall damaging approach to reducing malaria related mortality.
The 1940s saw DDT erroneously being used to prevent Polio through a program of street spraying. This was also a time when the effects of nuclear explosions were tested on human subjects. Do we need to "go there" again?!!
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