150 research outputs found
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
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
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Levels and Determinants of DDT and DDE Exposure in the VHEMBE Cohort.
BackgroundAlthough indoor residual spraying (IRS) is an effective tool for malaria control, its use contributes to high insecticide exposure in sprayed communities and raises concerns about possible unintended health effects.ObjectiveThe Venda Health Examination of Mothers, Babies and their Environment (VHEMBE) is a birth cohort study initiated in 2012 to characterize prenatal exposure to IRS insecticides and exposures' impacts on child health and development in rural South Africa.MethodsIn this report, we describe the VHEMBE cohort and dichlorodiphenyltrichloroethane (DDT) and dichlorodiphenyldichloroethylene (DDE) serum concentrations measured in VHEMBE mothers when they presented for delivery. In addition, we applied a causal inference framework to estimate the potential reduction in population-level p,p'-DDT and p,p'-DDE serum concentrations under five hypothetical interventions. A total of 751 mothers were enrolled.ResultsSerum concentrations of p,p' isomers of DDT and DDE were above the limit of detection (LOD) in ≥98% of the samples, whereas the o,p' isomers were above the LOD in at least 80% of the samples. Median (interquartile range) p,p'-DDT and p,p'-DDE serum concentrations for VHEMBE cohort participants were 55.3 (19.0-259.3) and 242.2 (91.8-878.7) ng/g-lipid, respectively. Mothers reporting to have lived in a home sprayed with DDT for malaria control had ~5-7 times higher p,p'-DDT and p,p'-DDE serum concentrations than those who never lived in a home sprayed with DDT. Of the five potential interventions tested, we found increasing access to water significantly reduced p,p'-DDT exposure and increasing the frequency of household wet mopping significantly reduced p,p'-DDT and p,p'-DDE exposure.ConclusionOur findings suggest that several intervention approaches may reduce DDT/DDE exposure in pregnant women living in IRS communities. https://doi.org/10.1289/EHP353
The interpretation of a semen analysis : semen analysis is still a cornerstone laboratory evaluation
Male factor infertility is solely responsible in ∼20% of cases and contributory in ∼30 - 40%. Therefore, in at least 50% of cases a male factor for infertility contributes to failure to conceive. A semen analysis is still a cornerstone laboratory evaluation and contributes to defining the severity of a possible single or contributing male factor to a couple's infertility.http://www.cmej.org.za/index.php/cme
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
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
Late lessons from early warnings: science, precaution, innovation
'There was a strange stillness. The birds for example — where had they gone? Many people spoke about them, puzzled and disturbed. The feeding stations in the backyards were deserted. The few birds seen anywhere were moribund: they trembled violently and could not fly. It was a spring without voices ... only silence lay over the fields and woods and marsh.' The book Silent Spring by Rachel Carson is mainly about the impacts of chemicals (in particular in particular dichlorodiphenyltrichlorethane also known as DDT) on the environment and human health. Indeed, the close association between humans and birds remains very apt. Representing the only two warm-blooded groups of life on Earth, mammals and birds share the same environments and threats. Carson's claim that she lived in 'an era dominated by industry, in which the right to make a dollar at whatever cost is seldom challenged' still resonates strongly with the problems that societies face all over the world. One chapter heading, 'The obligation to endure', derived from the French biologist and philosopher Jean Rostand's famous observation that, 'the obligation to endure gives us the right to know'. United States President John F. Kennedy responded to the challenge posed by Carson by investigating DDT, leading to its complete ban in the US. The ban was followed by a range of institutions and regulations concerned with environmental issues in the US and elsewhere, driven by public demand for knowledge and protection. DDT was the primary tool used in the first global malaria eradication programme during the 1950s and 1960s. The insecticide is sprayed on the inner walls and ceilings of houses. Malaria has been successfully eliminated from many regions but remains endemic in large parts of the world. DDT remains one of the 12 insecticides — and the only organochlorine compound — currently recommended by the World Health Organization (WHO), and under the Stockholm Convention on Persistent Organic Pollutants, countries may continue to use DDT. Global annual use of DDT for disease vector control is estimated at more than 5 000 tonnes. It is clear that the social conscience awakened by Rachel Carson 50 years ago gave momentum to a groundswell of actions and interventions that are slowly but steadily making inroads at myriad levels. Chapter 17 of her book, 'The other road' reminds the reader of the opportunities that should have been seized much earlier. With more than 10 % of bird species worldwide now threatened in one way or another, it is clear that we missed early warnings or failed to act on them. Will we continue to miss signposts to 'other roads'? Are our obligations to endure met by our rights to know? As Carson said 50 years ago: 'The choice, after all, is ours to make.
Lack of endocrine disrupting effects in catfish (Clarias gariepinus) from a DDT sprayed area
The exposure and response of the catfish, Clarias gariepinus, was studied in male specimens collected in the vicinity of a DDT spraying programme to control malaria. Two sites were situated in the DDT sprayed areas and one site upstream from exposed areas, used as a reference site the collected specimens were analysed for DDT bioaccumulation and the extent of associated effects. The concentration of all DDT metabolites including p,p’ –and o,p’ –forms of DDT, DDE and DDD, were measured in the adipose tissue, whilst the effects were measured using a range of biomarkers. This included assessing the effectiveness of plasma calcium, magnesium, zinc and alkali-labile phosphates (ALPs) as indirect measures of vitellogenin (VTG). Gonad condition was determined by calculating the gonadosomatic index (GIS) for each individual and comparing it with the gonad mass that were adjusted with Analysis of Covariance (ANCOVA). The presence of intersex in gonads was identified and the overall body condition determined using the condition factor (CF). Overall, none of the biomarkers showed significant change in the presence of high levels of DDT nor lindane, dieldrin and endosulfan II. Subtle responses is the plasma concentrations of calcium, ALP and gonad condition were evident in the catfish where DDT concentrations were highest, whilst no effects related to intersex and body condition were evident. Overall this study highlighted the tolerance of C. gariepinus to DDT contamination, the practical implications of using biomarkers in developing countries, and the need for further research into developing biomarkers for much needed biomonitoring programmes in areas where malaria control programmes continue to use DDT.Water Research Commission (WRC) and the South African National Research Foundation (NRF).http://www.elsevier.com/locate/ecoen
Responses of laboratory exposed catfish (Clarias gariepinus) to environmentally relevant concentrations of p,p′-DDT
Technical grade DDT is annually sprayed for malaria control in many under developed countries world wide. Despite the controversy surrounding the use of DDT, minimal research concerning the effects
on indigenous fish species in these areas has been conducted. In this study, the objectives were to identify some of the effects of sprayed p,p’-DDT on the common African sharptooth catfish species
(Clarias gariepinus) under laboratory conditions. The effects were assessed by exposing specimens to three environmentally relevant concentrations of p,p’-DDT (0.66, 1.36 and 2.72 μg/l) for 21 days
and analysing a suite of biomarkers in the plasma, gonads and body morphometrics. The biomarkers were specifically selected based on their practicality in developing countries, which could potentially
be utilised for continued monitoring, and included alkali-labile phosphate (ALP), calcium, magnesium and zinc as the indirect measures of vitellogenin, gonadosomatic index, gonad mass manipulated
using analysis of covariance, and condition factor. The results showed no significant (P<0.05) dosedependent changes in the plasma, gonads and body condition of C. gariepinus, indicating that these species were not responsive to the p,p’-DDT concentrations when exposed sub-chronically. This lack of a response suggested that mature C. gariepinus are tolerant to 21 days exposure of low levels of p,p’-DDT.Water Research Commission (WRC), University of Johannesburg and the South African National Research Foundation (NRF).http://www.elsevier.com/locate/etaphb2013ay201
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