DDT and Malaria Prevention: Addressing the Paradox

Background: The debate regarding dichlorodiphenyltrichloroethane (DDT) in malaria prevention and human health is polarized and can be classified into three positions: anti-DDT, centrist-DDT, pro-DDT. Objective: We attempted to arrive at a synthesis by matching a series of questions on the use of DDT for indoor residual spraying (IRS) with literature and insights, and to identify options and opportunities. Discussion: Overall, community health is significantly improved through all available malaria control measures, which include IRS with DDT. Is DDT “good”? Yes, because it has saved many lives. Is DDT safe as used in IRS? Recent publications have increasingly raised concerns about the health implications of DDT. Therefore, an unqualified statement that DDT used in IRS is safe is untenable. Are inhabitants and applicators exposed? Yes, and to high levels. Should DDT be used? The fact that DDT is “good” because it saves lives, and “not safe” because it has health and environmental consequences, raises ethical issues. The evidence of adverse human health effects due to DDT is mounting. However, under certain circumstances, malaria control using DDT cannot yet be halted. Therefore, the continued use of DDT poses a paradox recognized by a centrist-DDT position. At the very least, it is now time to invoke precaution. Precautionary actions could include use and exposure reduction. Conclusions: There are situations where DDT will provide the best achievable health benefit, but maintaining that DDT is safe ignores the cumulative indications of many studies. In such situations, addressing the paradox from a centrist-DDT position and invoking precaution will help design choices for healthier lives

Environmental pollutants and diseases of sexual development in humans and wildlife in South Africa : harbingers of impact on overall health?

This study deals with disorders of sexual development in humans, wildlife and animals in an urban nature reserve (RNR) and a currently DDT-sprayed malarial area. High levels of oestrogenic chemical residues in water, sediment and tissue; skewed sex ratios; reduced biodiversity; gonadal malformations in sharptooth catfish and freshwater snails; intersex in catfish; and impaired spermatogenesis in catfish and striped mouse are of serious concern in the RNR. Persistent eggshell thinning in African darter eggs, intersex in male Mozambican tilapia, follicular atresia in females and impaired spermatogenesis in males following laboratory exposure of parent fish and impaired spermatogenesis in males following laboratory exposure of parent fish to environmentally relevant DDT and DDE concentrations, and abnormalities in freshwater snails were found in the DDT-sprayed area. Human studies related to DDT exposure indicated impaired semen quality, a weak association with sperm chromatin defects and higher risks for external urogenital birth defects in those who were born to mothers whose houses were sprayed and those who were homemakers (Stay at home mother) instead of being employed. These findings indicate that disease of sexual development occurred in both human and wildlife populations exposed to environmental endocrine disruptor chemicals in South Africa. The chemical mixtures, possibly related to disorders of sexual differentiation (DSD), were very different between the two. However, DSD occurred concurrently in the malarial area, possibly indicating that humans and wildlife shared exposures. Moreover, it emphasizes the importance of suspecting disease in the other when disease is found in either human or wildlife populations.The Medical Research Council, the Urological Association Society of Southern Africa, the Water Research Commission and the National Foundation for Research.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1439-053

Производственные мощности предприятия: оценка и направления повышения эффективности использования (на примере ОАО «Милкавита»)

Indoor residual spraying (IRS) has been and is still a very successful method to controlmalaria. We are concerned that not enough research attention is given to improvingIRS and that most funding goes towards modern but seemingly still ineffectualmethods. We believe that there is ample scope for improving IRS, while reducinginsecticide exposur

The paradox of the effectiveness of IRS insecticides (including DDT) and its impacts on human health - what can we fix if it isn’t broken?

The effectiveness of DDT and other insecticides when properly used as indoor residual spray (IRS) to combat malaria is not in question [1]. However, the high body burden of DDT of those protected is very high [2], and the human health consequences due to IRS insecticides of those protected are of great concern [1-3]. What may be questioned though are the effectiveness, health impacts, social consequences, and sustainability of some IRS alternatives. Many promising ‘silver bullets’ (using anything but IRS) to beat malaria over the last number of decades have come and gone. Yet, the one proven method, IRS, gets less recognition or attention. IRS interrupts transmission where most infections occur - the home. It is also at home where those most likely to suffer malaria - babies, children and pregnant mothers - are to be found. The negative part of the IRS message though, remains the inevitable co-exposure of the very same susceptible groups to IRS insecticides. Protection by IRS comes at a cost, creating a paradox -protection from deadly malaria may carry a health burden due to the IRS chemicals used [1,3].http://www.malariajournal.com/content/11/S1/P14ay201

Heavy metals in muscle tissue of healthy crocodiles from the Kruger National Park, South Africa

Mass mortality of Nile crocodile (Crocodylus niloticus) occurred in the Olifants River of the Kruger National Park (KNP) in 2008 from pansteatitis, a condition in which body fat becomes yellow and inflamed. Much research has been carried out, but the cause(s) of the outbreak in the KNP remains unknown (Ashton, 2010; Ferreira & Pienaar, 2011; Woodborne et al., 2012; Bouwman et al., 2014). Anthropogenic factors such as heavy metal pollution have been suggested as a potential cause (e.g. Bouwman et al., 2014). We found only three studies from Africa on heavy metals in wild crocodiles (Table 1). The aim of this study was to assess the concentrations of heavy metals and metalloids in wild and apparently healthy crocodiles in the KNP.http://onlinelibrary.wiley.com/journal/10.1111/(ISSN)1365-20282017-12-31hb2017Paraclinical Science

Household behavioural responses following successful IRS malaria control : challenges for health education and intervention strategies

No abstract available.http://www.malariajournal.com/content/11/S1/P12ay201

DDT exposure of frogs : a case study from Limpopo Province, South Africa

Amphibians are globally under pressure with environmental contaminants contributing to this. Despite caution aired more than 80 years ago of threats posed to amphibians by DDT spraying for disease vector control, no data have been published on concentrations or effects of DDT contamination in frogs from areas where DDT is actively sprayed to control the insect vectors of malaria. In this study, we sampled fat bodies of Xenopus laevis and Xenopus muelleri naturally occurring in an area where indoor residual spraying of DDT is employed and from adjacent, non-sprayed, areas. ΣDDT concentrations ranged between <LOQ and 280 ng/g ww (wet weight) from the non-sprayed area, and 5.5-910 ng/g ww from the sprayed area, but statistical significance could not be shown. We observed significant asymmetric testicular morphology in frogs from the sprayed area, possibly due to endocrine disruption by compounds such as the DDTs. A previous study from the same area found very high concentrations of DDT in the eggs of the Grey Heron Ardea cinerea. This suggests that the DDT we found in frogs may have contributed to DDT loadings higher in the food web. These findings, combined with other studies from this area, support the need to reduce and eventually move away from DDT in malaria control safely and sustainably.South African Water Research Commission (WRC) and the National Research Foundation (NRF).http://www.elsevier.com/locate/chemosphere2017-09-30hb2016School of Health Systems and Public Health (SHSPH

Chlorinated, brominated, and fluorinated organic pollutants in Nile crocodile eggs from the Kruger National Park, South Africa

Repeated annual episodes of Nile crocodile deaths in two isolated areas of the Kruger National Park prompted the investigation of possible organohalogen pollutant involvement.Crocodile eggs were collected close to one of the mortality sites (Gorge) as well as from a crocodile farm (CF) as reference. ΣDDT was significantly higher in Gorge (450ng/gwm) than in CF eggs (85ng/gwetmass). Percentage DDT of ΣDDT was significantly higher in CF (14 percent)than in Gorge eggs (5 percent). Mean ΣDDT was almost 70 times higher than mean ΣPCB in Gorge eggs. HCB, β-HCH, mirex, brominated flame retardants (BFRs), and perfluorinated compounds (PFCs) occurred at lower concentrations. We believe that the BFR and PFCs data represent the first published results for any crocodile egg.Thickening of the outer egg shell layer of Gorge eggs was significantly associated with higher concentrations of ΣDDT. Concentrations of ΣDDT and other pollutants were in the same range as eggs from elsewhere,where there were no mortalities. Concentrations of ΣDDT in eggs from healthy Australian crocodiles were of the same orders of magnitude as the current study, making it highly unlikely that the concentrations of pollutants measured in the present study would have caused or substantially contributed towards the mortalities observed.Concerns about reproduction and behaviour remain.As large predators, crocodilians are at the apex of the freshwater aquatic food web.More research is needed to guide measures to manage African freshwater systems so that it will also sustainably accommodate these large, long-lived animals.Ruppert Foundation and Billy duToit.http://www.elsevier.com/locate/ecoenvhb201

Malaria Control Insecticide Residues in Breast Milk: The Need to Consider Infant Health Risks

http://dx.doi.org/10.1289/ehp.090060

Implications for health education and intervention strategies arising from children's caregivers concerns following successful malaria control

We investigated the interaction between social and economic circumstances with malaria awareness in rural South African villages effectively protected from malaria infection by community-passive, indoor residual spray (IRS) performed by government. We conducted interviews with 120 caregivers of children using both open-ended and closed fixed-answer questions. The mean income was between 27 and 56% of the national mean, indicating a community under considerable pressure. Male parents were often absent due to work commitments. Unemployment, poverty, crime, and clean water were the main, unprompted, threats, but malaria was volunteered by none. Only when malaria was prompted (caregivers had good knowledge of malaria), did its concern rise. Malaria, therefore, was not a prominent conscious concern. This implies that alternatives to IRS that require increased community and personal engagement, behavioural changes, and time commitment (such as certain components of integrated vector management and bed nets), will face implementation challenges. Unless community-passive malaria control measures can be developed that is as good or better than IRS, it seems unreasonable to expect poor communities to adopt community-active systems. Our findings should be considered in malaria control strategies, rural policy development, climate change adaptation, and communication strategies.National Research Foundation (NRF) of South Africa and the Post-doctoral Programme of the University of Pretoria.http://www.elsevier.com/locate/trstm