PROS AND CONS OF DDT USE FOR UGANDA

FACTORS/ ISSUE	PROS (BENEFITS) OF DDT USE IN UGADA	CONS (PROBLEMS) OF DDT USE FOR UGANDA:
ECONOMIC (COST ISSUES)	A recent 1998/99 cost data presented indicate that DDT is still the cheapest insecticide to employ for IRS in vector control programmes on the basis of cost per house per 6 months of control, (provided that its use achieves satisfactory control of Anopheles and malaria). However, the cost differential appears to be declining and may be insignificant in some countries, with cost ratio of DDT to other insecticides varying between 1.4-18.7 (Walker, 2000). The long residual effect of DDT lasting for up to 6 or more months reduces the operational DDT IRS costs.	DDT price has risen already and is expected to rise further as the DDT volume and number of producers declines (only 3 major manufacturers worldwide – 2 in China and 1 in India), coupled with international pressure to ban DDT manufacture and use DDT spraying requires and well trained, motivated (paid) and well supervised team with proper protective wear, thus increasing its operational costs DDT IRS requires effective regulation to avoid its diversion for agricultural purposes and this may increase its operational costs Based on the product weight calculations of US $ 1,100/ton figure (Goodman et.al., 1999, 2000), transportation costs for DDT are higher than some pyrethoids, with DDT shipping costs at US $ 1.76 per house per 6 months compared to US $ 0.06-0.11per home per 6 months for Icon. Local transportation costs of DDT are also higher because of its bigger volume. This increases the operational DDT IRS costs. With DDT (and other coarse abrasive) WP formulations, the nozzle tip (costing ~ US $ 1.00) may have to be replaced after each spray cycle, whereas nozzle tips can be used without replacement for years when spraying the finer WP formulations of some potent pyrethroids that also remain active for 6 months on the sprayed wall surface. This increases the operational DDT IRS costs.
EFFICACY (RESIDUAL EFFECT)	DDT is effective for up to 6 or more months and thus can be applied only twice a year in areas of two rainy season and only once in areas where there is one long wet and 1 long dry season. Despite the development of resistance to DDT in some populations of malaria vector anopheles mosquitoes, DDT remains generally effective when used in indoor spraying against most species of anopheles, due to excitorepellency as well as insecticidal effects.	In view of the availability of alternative insecticides for IRS, some of which may compete with DDT in terms of epidemiological impact, public acceptability, logistic suitability and compliance with specifications issued by WHO, DDT no longer merits being considered the only insecticide of choice (WHO, 2000)
INSECTICIDE RESISTANCE	An. funestus (not An arabiensis) became resistant to deltamethrin in South Africa and because of a serious epidemic in the country, DDT was again used for the spraying of houses to control the epidemic.	High levels of DDT resistance in malaria vectors has been recorded in some countries e.g. Sri Lanka and parts of India and Mexico, requiring the use of other alternative insecticides. There is need therefore to assess DDT resistance status of the major local malaria vectors in Uganda
HEALTH (SAFETY ISSUES)	DDT is poorly absorbed through the skin, making it relatively safe insecticide to handle (Smith et. al 1992). A claimed association between DDE residues with breast cancer have not yet been substantiated (Curtis, 2002) A review of two recent publications suggesting an association between DDT and human cancers, a report on the presence of DDT in breast milk, and two general reviews of the subject by two Expert Toxicologists concluded that the information presented does not provide convincing evidence of adverse effects of DDT exposure as a result of IRS as carried out in malaria control activities (WHO, 2000). A WHO study group concluded that DDT exposure associated with IRS does not constitute a significant health hazard (WHO, 1995). Thus there is very limited evidence that indoor DDT spraying is associated with negative impacts in human health.	There are lingering concerns about the long term effects of chronic exposure (WWF , 1998, 1999) Some research suggests that DDT and its metabolite DDE may interfere with normal functioning of certain hormone mediated process. DDT does not break down quickly and has a persistent effect in the environment and accumulates in human and animal fats for up to 20 years after exposure to DDT ends and is expressed in breast milk. Although Sweden banned DDT use in 1970 and was banned in most other countries in 1972 following clear evidence of the harm it caused to wildlife, nevertheless, high levels continue to be found in the blood or fatty tissues of people around the world. This includes the Innuit people of Greenland, who have not been exposed to DDT in spray form but who eat large amounts of fat from contaminated sea mammals (De Jager et. al. 2003). Recent studies in Chiapas province, Mexico, a rural area where DDT was used to control malaria until the late 1990s, showed that high DDT levels in men could alter male hormone balances and decrease sperm quality, including reduced ability to swim fast, lower than normal semen volumes lower sperm counts. High levels of DDT exposure were found in the blood of the tested men (about 300 times higher than breast milk samples from Canadian women). DDE (DDT metabolite) residues in breast milk has been associated with DDT anti-malaria spraying in South Africa but it is not known whether this is harmful (Bouwman et.al., 1990). There is also a recent report of association of DDE residues with the probability of pre-mature birth and shorter duration of lactation, although no studies in Africa have shown this association (Curtis, 2002; Chen, et. Al., 2003). Proper protective wear required for the spray team using DDT
ENVIRONMENTAL ISSUES	The heavy use of insecticides for IRS could be expected to have an impact on the environment, but there is little information documenting this. Most of the documented environmental damage caused by DDT is associated with heavy use in agriculture (e.g. Wurster et.al. 1965, Risebrough, 1972, Wiemeyer et.al. 1993)	DDT is an organochlorine compound which has a persistent damaging effect in the environment. Agricultural DDT overuse in the 1950s and 1960s devastated some wildlife populations, such as birds of prey, whose effects on these populations are reversing only now. Due to environmental concerns, DDT should only be used in well defined, high or special risk populations, thus restricting areas where it is to be used The washing of spraying equipment and poor disposal of waste DDT solution may cause some risk to contamination of streams of streams and other ecosystems near IRS operations The long persistence of DDT and its metabolites in soil may result in adverse impacts of large scale DDT spray programmes over a long period (WWF, 1998, 1999) Diversion of DDT from public health use to agricultural applications, through pilferage and corruption, also causes various problems, including contamination of export crops with unacceptable insecticide residues (WHO, 1999)
SUPPLY ISSUES		Continued supply of DDT may become a problem as only 3 major DDT production facilities currently in the world continue to operate (2 in China and 1 in India), India does not export its DDT. Thus, countries like Uganda may encounter problems of a constant supply of DDT.
POLITICAL AND ECONOMIC PRESSURES		DDT is being phased out because of its previous widespread use in the environment, and resulting political and economic pressure Some wealthier nations have demanded that poorer countries ban DDT as a condition for receiving foreign aid. USA and EU countries may put pressure on Uganda not to re-introduce DDT by threatening not to import agricultural and fisheries products related goods if DDT is being used in the country. This could easily apply to Uganda’s agricultural Areas to be sprayed may be major tourist destinations where there are game and nature reserves. The knowledge that DDT is used in this environment could potentially turn tourists away who have perceived ideas of pristine natural environment although malaria posses a greater risk to the tourists
SOCIAL IMPLICATIONS	DDT kills other household pests DDT is only effective on porous walls such as mud-plastered walls. Thus its effectiveness will be appreciated by the local communities where mud-plastered walled houses are the main type of houses used. DDT stains walls white and this makes quality control of spraying operations extremely easy.	DDT irritates and increases activities of bedbugs in households that have been sprayed leading to certain household members refusing access to malaria control personnel who are unable to spray. This affects coverage which is very critical for achieving Anopheles mosquito and malaria control Cement and brick houses with plaster and painted walls are unsuitable for DDT. Spraying furniture with DDT could damage it and would be very unpopular. This is likely to reduce coverage rates in villages where many houses are of cement and brick. DDT stains walls white and some householders find the staining unacceptable and tend to re-plaster after the malaria control personnel have left. The re-plastering covers over the DDT and therefore leaves it ineffective

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