Use Of Dichlorodiphenyltrichloroethane Research Articles

Fight against Typhus in Turkey (1945-1950)

Objective: The aim of this study is to examine the struggle against typhus, which has been a scourge of humanity for centuries, in Turkey between 1945 and 1950. Method: The data of our study were obtained from archival documents, periodicals of the period and other studies in the literature. In addition, this study is a qualitative study and document analysis method was used. Findings: The fight against typhus, which became epidemic in Turkey during World War II, became one of the most important issues of the post-war period. In the fight against typhus, vaccination had begun in 1943, during the war years. This practice would be accelerated as of 1945. The vaccine produced in large quantities in a short period of time at the Refik Saydam Institute of Public Health played a significant role in this situation. In addition, the effective use of dichlorodiphenyltrichloroethane (D.D.T.) from 1945 onwards constituted one of the most important factors in achieving success. Conclusion: Thanks to the preventive health measures taken between 1945 and 1950, as well as the strict vaccination program and D.D.T. application, Turkey was able to reduce typhus disease, one of the most feared disasters of those years, from the country's agenda.

Isolation and Characterization of a Novel p,p’-DDT-Degrading Bacterium: Aeromonas sp. Strain MY1 from Agricultural Soil

Background: Despite the banned on the use of dichlorodiphenyltrichloroethane (DDT) and other Persistent Organic Pollutants (POPs) by the Stockholm Convention for their toxicity, emerging shreds of evidence have indicated that DDT is, however, still in use in developing countries. This might increase the global burden of DDT contamination and its hazardous effects.
 Aim: This study focused on the isolation and characterization of p,p’-DDT-degrading bacterium from a tropical agricultural soil.
 Methodology: Standard isolation procedure was used for the screening and isolation of the strain. The 16S rRNA and phylogenetic analyses were used to identify the isolate and established protocols were followed to characterize the strain.
 Results: A new strain belonging to the genus Aeromonas was isolated from agricultural soil using minimal salt-p,p’-DDT enrichment medium. The 16S rRNA sequencing was used to identify the strain and the partial sequence was deposited in the NCBI GenBank as Aeromonas sp. Strain MY1. This mesophilic isolate was capable of utilizing up to 50 mgL-1 of p,p’-DDT as the sole carbon source at an optimum pH of 7.5 and optimum temperature of 35 °C within 120 h under aerobic conditions. Fe2+ (0.2 mgL-1) demonstrated a stimulatory effect on the p,p’-DDT degradation capacity by the strain MY1. However, Zn, Cu, Pb, Hg, Ag and Cr ions have demonstrated various patterns of inhibitory effect on the p,p’-DDT degradation capacity of the isolate at 0.2 mgL-1. The strain MY1 could be a promising candidate for the bioremediation of p,p’-DDT contaminant.
 Conclusion: Aeromonas sp. strain MY1 was capable of utilizing p,p’-DDT as a sole carbon source under aerobic conditions. The utilization capacity of the strain was influenced by some heavy metals. Fe was found to enhance the p,p’-DDT utilization capacity of the isolate at a lower concentration. While Zn, Cu, Pb, Hg, Ag and Cr showed various patterns of inhibitory effect.

Chemical and microbiological hazards of Khat (Catha edulis) from field to chewing in Ethiopia

Catha edulis of the plant family Celastraceae commonly named as Khat in Ethiopia is a stimulant plant containing amphetamine-like substances. Fresh Khat leaves described to contain some 60 different constituents. Consumers chew leaves and masticate it for hours. Some users make a paste from dried leaf powder, mixing with sugar and water which is easily chewed and swallowed. In some areas, dried leaves are used as a tea, and also crushed and rolled into cigarettes. Less attention has been directed toward possible chemical and microbial contamination and risky pathways. The aims of this study are 1.Identify the actual Khat production-consumption process from farm to use. 2. Detect chemical and microbial contamination risk of consumable Khat leaf in process 3. Assess the microbiological qualities chewable Khat leaf. Descriptive statistics from the main dataset, for Khat consumption, showed that out of 1169, 564 household heads were Khat consumers and out of these consumers, 347 (62.52%) consume daily. Majority of the pilot study participants (retailers and consumers) confirmed that pesticide chemicals are sprayed on Khat bushes and trees, and Khat farmers disclosed the use of Dichlorodiphenyltrichloroethane (DDT) and Malathion on their farm. The mean CFU/gm was 1.69*10^5 which indicate poor hygiene /handling. Our observation showed that the processes from farming, Transporting, collection, distribution (whole-sellers, retailers) to consumption indicate a potential risk for Khat leaf to become contaminated with Chemicals/ microorganisms.

Rickettsiae Within the Fleas of Feral Cats in Galveston, Texas.

Murine typhus is a flea-borne typhus group rickettsiosis caused by Rickettsia typhi. Once a prevalent disease in the United States, the use of dichlorodiphenyltrichloroethane in the 1940s broke the classic rat-rat flea cycle of transmission, and the remaining endemic foci are now believed to be associated with opossums and the cat flea (Ctenocephalides felis). In Galveston, Texas murine typhus has re-emerged as a cause of febrile illness, and 7% of fleas collected from opossums are infected with R. typhi. In this study, we sought to explore the prevalence of rickettsiae associated with fleas on cats, as these animals have been speculated to play a role in the epidemiology of murine typhus. Fleas were collected from feral cats entering a local veterinary clinic as part of a trap, spay, neuter, and release program. Fleas were identified and subjected to analysis by PCR and sequencing. An estimation of the minimum infection rate (MIR) of pooled samples was performed. Three hundred fourteen fleas (all C. felis) were collected from 24 cats. Sequences for the outer membrane protein B gene revealed R. typhi in one pool (MIR 0.3%), Rickettsia felis in four pools (MIR 1.3%), Rickettsia asembonensis in one pool (MIR 0.3%), and "Candidatus R. senegalensis" in six pools (MIR 2.0%). Results were confirmed by sequencing portions of the rickettsial citrate synthase and 17-kD protein gene. In this study, the presence of R. typhi in fleas from cats suggests that in Galveston, there exists a small but measurable risk to humans who come into contact with flea-infested cats. Despite this, we believe that the low prevalence from cat-collected fleas, compared with that previously detected from opossums, makes cats less likely to play a role in the maintenance of R. typhi in this region. The significance of other identified flea-borne rickettsiae is yet to be elucidated.

Integrating bioavailability and soil aging in the derivation of DDT criteria for agricultural soils using crop species sensitivity distributions

Although the agricultural use of dichlorodiphenyltrichloroethane (DDT) has been banned for decades in many countries around the world, the detection of DDT and its metabolites in soils is very common due to their persistence. DDTs (sum of DDT and its metabolites) in farmland soils can be absorbed by crops at different levels and accumulate in the edible parts of agricultural products, posing threats to the health of human being. However, no information on the species sensitivity distribution (SSD) of crops with regard to DDTs has been reported due to the lack of enough bioavailability data and models to normalize the bioavailability data from different sources. Based on the bioconcentration factors of 17 crop species in Chinese soils obtained from previous studies, the criteria of DDTs in soils was derived according to the quality standard of agricultural products using the SSD method. Corrections for water content and aging time were conducted to normalize the data from different sources. The risk values of agricultural products at different concentration levels of DDTs in soils were also evaluated. It was found that oil crops are able to take up more DDTs than non-oil crops, so the soil criteria were calculated separately for oil crops and non-oil crops, which were 0.083 mg/kg and 0.29 mg/kg, respectively. With the residual concentrations of DDTs in soils at the range of 0.01–0.5 mg/kg, 0–8% of the agricultural products exceeded the permissible limits for DDTs which were set in the National Food Safety Standard of China. The results also demonstrated the feasibility for applying SSDs to derive the soil criteria of DDTs in order to ensure the safety of agricultural products. This work will provide information for the risk assessment and the establishment of soil environmental quality standards to ensure safe agricultural production.

Malaria outbreak investigation - Mopani and Vhembe districts, Limpopo province, South Africa, May 2017

Introduction : South Africa (SA) has set a goal of malaria elimination by 2018. Malaria remains a major public health challenge in Vhembe and Mopani districts, Limpopo province-two of the five malaria endemic districts in SA. On 2 May 2017, health facilities in the two districts reported an unusual increase of malaria cases. Investigations were conducted to establish existence, magnitude and cause of the outbreak, to recommend control measures for the current outbreak and future prevention. Methods : a cross-sectional investigation was conducted. Discussions with key stakeholders were held. We reviewed malaria case data collected through the Limpopo provincial malaria information system from April to May 2017. We defined a case as a person with malaria confirmation by microscopy or a rapid diagnostic test (RDT) in health facilities of the two districts from April to May 2017. Results : a total of 5 662 cases, 55.3% in Mopani, were reported with a peak in May 2017.Investigation of likely origin revealed that 5 574 (98.4%) were local cases in both districts. Fifty-four malaria deaths were reported, majority 42 (77.8%) in Mopani district. The median age of the patients who died was 44 years (IQR 35-60) with 0.95% case fatality rate (CFR). 99.9% of all cases were Plasmodium Falciparum. Indoor residual spraying (IRS) coverage was less than WHO recommended 80% universal coverage for control. An environmental assessment revealed that 2016/17 season recorded higher levels of rainfall and temperature compared to previous malaria season. Key stakeholder interviews revealed that the outbreak in the province was associated with late commencement of IRS due to late appointment of spray teams; reduced use of Dichlorodiphenyltrichloroethane (DDT) which was replaced by pyrethroids (K-Othrine and Deltamethrine); and stock outs of RDTS and anti-malaria drugs in clinics. Conclusion : the investigation established that the marked increase in malaria cases in Vhembe and Mopani districts was not a seasonal phenomenon but rather an outbreak. We recommended a community awareness program through local radio stations on malaria prevention and treatment; improved supply chain of RDTs and antimalarial drugs to prevent stock outs; budget allocation for procurement of DDT and advance appointment of IRS teams.

Linking environmental exposure with public health: dichlorodiphenyltrichloroethane extracted from soils and water of recently exposed communities of selected locations in Zambia.

Background. In 2000, a Zambian private mining company reintroduced the use of dichlorodiphenyltrichloroethane (DDT) to control malaria in two districts. From 2000 to 2010, DDT had been applied in homes without any studies conducted to ascertain its fate in the environment. We aimed to quantify the presence of DDT and its metabolites in the soil and water around communities where it was recently used. Methods. We collected superficial soil and water samples from drinking sources of three study areas. DDT was extracted by QuEChERS method and solid phase extraction for soils and water, respectively. Analysis was by gas chromatography-mass spectrometry. A revalidated method with limits of detection ranging from 0.034 to 0.04 ppb was used. Results. Median levels of total DDT were found at 100.4 (IQR 90.9–110) and 725.4 ng/L (IQR 540–774.5) for soils and water, respectively. No DDT above detection limits was detected in the reference area. These results are clinically significant given the persistent characteristics of DDT. Conclusion. DDT presence in these media suggests possible limitations in the environmental safeguards during IRS. Such occurrence could have potential effects on humans, especially children; hence, there is a need to further examine possible associations between this exposure and humans.

Trends in eggshell thickness and mercury in common goldeneye and hooded merganser eggs

ABSTRACTEnvironmental contaminants such as dichloro diphenyl trichloroethane (DDT), polychlorinated biphenyls (PCBs), and mercury are associated with physiological problems in wildlife. DDT and PCBs were banned in North America in the 1970s, but these contaminants sometimes persist in the environment and can cause reproductive problems, including eggshell thinning. In contrast, mercury deposition from anthropogenic sources is a continuing if not growing concern globally. We measured thickness of common goldeneye (Bucephala clangula) and hooded merganser (Lophodytes cucullatus) eggshells collected in 2003–2004 in Minnesota, USA, to compare with measurements taken prior to (approx. 1900) and after (1981) widespread DDT use. We also compared egg‐mercury concentration (ppm) in goldeneye and merganser eggs collected in 2003–2004 with a 1981 collection. Mean eggshell thickness was 0.401 mm (SE = 0.003) and 0.606 mm (SE = 0.008) for goldeneyes and mergansers, respectively. This was 9.0% (goldeneyes) and 6.0% (mergansers) greater than in 1981. Mean thickness of goldeneye eggshells remained 7.8% less than the mean prior to widespread DDT use; whereas, merganser eggshell thickness was statistically similar to pre‐DDT thickness. Mean Ratcliffe's index, a measure of eggshell quality, also increased for goldeneyes (2.52, SE = 0.021) and mergansers (3.78, SE = 0.042) since 1981. Goldeneye values were statistically similar to, while merganser values remained 5.6% less than, pre‐DDT values. Geometric mean concentrations of mercury (wet wt) have declined since 1981 in merganser eggs (0.33 ppm, SE = 0.024), and were statistically unchanged in goldeneye eggs (0.13 ppm, SE = 0.011). Continued monitoring of wildlife populations for contaminants is important because wildlife may serve as an indicator of overall ecosystem health. © 2013 The Wildlife Society.

Field Validation of Anaerobic Degradation Pathways for Dichlorodiphenyltrichloroethane (DDT) and 13 Metabolites in Marine Sediment Cores from China

Although the production and use of dichlorodiphenyltrichloroethane (DDT), a legacy component of persistent organic pollutants, have been highly restricted worldwide, the environmental fate of DDT has remained a great concern as it is not only ubiquitous and bioaccumulative but can also be degraded to a series of metabolites that may be more hazardous ecologically. The present study, taking advantage of the abundant levels of DDT and its metabolites in a subtropical coastal region of China, investigated into the degradation pathways of DDT in natural coastal sediment. Sediment profiles indicated that degradation of 1,1,1-trichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDT) to 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDD) mainly occurred in sediment of the top 20 cm layer. 1,1-dichloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDE), aerobically transformed from p,p'-DDT prior to sedimentation, was likely to degrade to 1-chloro-2,2-bis-(p-chlorophenyl)ethylene (p,p'-DDMU) which was further converted to 2,2-bis(p-chlorophenyl)ethylene (p,p'-DDNU). In addition, p,p'-DDNU could be transformed to 2,2-bis(p-chlorophenyl)ethane (p,p'-DDNS) and other high-order metabolites. On the other hand, the conversions of p,p'-DDD to p,p'-DDMU and 1-chloro-2,2-bis-(p-chlorophenyl)ethane (p,p'-DDMS) to p,p'-DDNU were deemed slow in anaerobic sediment. Therefore, the present study confirmed all the degradation pathways involving reductive dechlorination and p,p'-DDE being a more important precursor for p,p'-DDMU than p,p'-DDD in anaerobic sediment, as proposed previously. On the other hand, the present study suggested that p,p'-DDMU instead of p,p'-DDMS was more likely the precursor for formation of high-order metabolites. Based on the current assessments, use of (DDD+DDE)/DDTs to indicate whether there is fresh DDT input may lead to large uncertainties if the concentrations of high-order metabolites are not negligible. Similarly, ecological risk assessment associated with DDT should be conducted with consideration of high-order DDT metabolites.

Household size explains successful malaria eradication

Malaria is prevalent in 108 countries and has been eradicated from 80 countries. Malaria has only permanently disappeared in Palestine and Maldives because of complete eradication of vectors. Otherwise the explanation varies from changes in animal husbandry, switching of Anopheles species, draining of wetlands, use of dichlorodiphenyltrichloroethane (DDT), or changes in the climate. Country data of malaria frequency was tested with a simple correlation test and a Chi Square test for household size, gross domestic product (GDP) per capita, population density and urbanization level. There was no correlation between malaria frequency and population density. Household size was the only factor with a specific threshold value when malaria disappeared, i.e. a household size lower than four members. This threshold value was also valid across all climate zones independently of 50-70 different vector species and 4(-5) different Plasmodium species. Only seven countries made an apparent exception. Although they hade a low average household size, malaria was predominantly prevalent in areas or provinces where the average household size was higher than four. China was the only country for which the provincial statistics were too crude for proper analysis. Malaria frequency also has a high negative correlation with GDP and urbanization. GDP per capita does not as such explain malaria trends, but affects urbanization and household size. Increasing urbanization level improves housing conditions with an increasing share of multi-storey buildings, which reduces human contact with the vectors. The importance of household size as the key explanatory variable for malaria prevalence implicates that land development, settlement planning and the planning of exploration of natural resources should be implemented in malaria eradication. Sudden and uncontrolled population movements into an area cause a rise of malaria cases. This can be seen in areas such as Rondonia and Mato Grosso in Brazil. Mosquito control alone cannot lead to malaria eradication, though it is essential for preventing epidemics. The extensive use of DDT in the 1940s and 1950s showed that in countries with a low household size eradication campaigns were successful but in countries with a household size above four members malaria returned with the DDT ban.

Historical Perspectives on Malaria: The Rockefeller Antimalaria Strategy in the 20th Century

Malaria, a serious disease for all of human history, was not effectively handled until methods for control of its insect vector, the Anopheles mosquito, were developed at the beginning of the 20th century. The Rockefeller Foundation's antimalaria program spread vector-control strategies throughout the world, and its adoption of dichlorodiphenyltrichloroethane during World War II created an especially powerful and effective malaria control strategy. However, insect resistance to dichlorodiphenyltrichloroethane and restrictions on dichlorodiphenyltrichloroethane use due to its long-term environmental effects are factors in the persistence of malaria as a serious health problem. Mt Sinai J Med 76:468-473, 2009. (c) 2009 Mount Sinai School of Medicine.

Organochlorine pesticides and polychlorinated biphenyls in soil and water samples in the Northeastern part of São Paulo State, Brazil

Detailed analyses of persistent organic pollutants (POPs) such as organochlorine pesticides (OCPs), hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs) and congeners of polychlorinated biphenyls (PCBs) in soil and surface water from the northeastern São Paulo, Brazil allowed the evaluation of the contamination status, distribution and possible pollution sources. The pesticides and PCBs demonstrated markedly different distributions, reflecting different agricultural, domestic and industrial usage in each region studied. The ranges of HCH, DDT, and PCBs concentrations in the soil samples were 0.05–0.92, 0.12–11.01, 0.02–0.25 ng g −1 dry wt, respectively, and in the surface water samples were 0.02–0.6, 0.02–0.58 and 0.02–0.5 ng l −1, respectively. Overall elevated levels of DDT and PCB were recorded in region 2, a site very close to melting, automotive batteries industries, and agricultural practice regions. High ratios of metabolites of DDT to DDT isomers revealed the recent use of DDT in this environment. The sources of contamination are closely related to human activities, such as domestic and industrial discharge, street runoff, agricultural pesticides and soil erosion, due to deforestation as well as atmospheric transport.

Toxicology and the environment: An IUPAC teaching program for chemists

Increasingly, chemists are faced with legislation requiring assessment of hazard and risk associated with the production, use, and disposal of chemicals. In addition, the general public are concerned about the dangers that they hear may result from the widespread use of chemicals. They look to the chemist for explanations and assume that chemists understand such matters. When they discover that chemists are often ignorant of the potential of chemicals to cause harm, their confidence in the profession is lost and chemophobia may result. In 1993, IUPAC agreed on a joint project between the Toxicology Commission and the Committee on Teaching of Chemistry to address the issue of the teaching of toxicology in the chemistry curriculum. Part of the project was a distance learning program, which is available through the Internet and on CD.1 The program currently consists of seven modules, one of which deals specifically with environmental toxicology. The contents of each unit will be explained as each has some input into environmental matters and green/sustainable chemistry. The program is aimed at teacher and student alike, and each module has self-assessment exercises at the end of the module. Additionally, there is material on health and safety, ethical matters, and a case study of the use of dichlorodiphenyltrichloroethane (DDT).

Neurochemical Targets and Behavioral Effects of Organohalogen Compounds: An Update

Organohalogen compounds (OHCs) have been used and still are used extensively as pesticides, flame retardants, hydraulic fluids, and in other industrial applications. These compounds are stable, most often lipophilic, and may therefore easily biomagnify. Today these compounds are found distributed both in human tissue, including breast milk, and in wildlife animals. In the late 1960s and early 1970s, high levels of the polychlorinated biphenyls (PCBs) and the pesticide dichlorodiphenyl trichloroethane (DDT) were detected in the environment. In the 1970s it was discovered that PCBs and some chlorinated pesticides, such as lindane, have neurotoxic potentials after both acute and chronic exposure. Although the use of PCBs, DDT, and other halogenated pesticides has been reduced, and environmental levels of these compounds are slowly diminishing, other halogenated compounds with potential of toxic effects are being found in the environment. These include the brominated flame retardants, chlorinated paraffins (PCAs), and perfluorinated compounds, whose levels are increasing. It is now established that several OHCs have neurobehavioral effects, indicating adverse effects on the central nervous system (CNS). For instance, several reports have shown that OHCs alter neurotransmitter functions in CNS and Ca2+ homeostatic processes, induce protein kinase C (PKC) and phospholipase A2 (PLA2) mobilization, and induce oxidative stress. In this review we summarize the findings of the neurobehavioral and neurochemical effects of some of the major OHCs with our main focus on the PCBs. Further, we try to elucidate, on the basis of available literature, the possible implications of these findings on human health.

Changes in productivity and contaminants in bald eagles nesting along the lower Columbia River, USA

Previous studies documented poor productivity of bald eagles (Haliaeetus leucocephalus) in the lower Columbia River (LCR), USA, and elevated p,p'-dichlorodiphenyldichloroethylene (DDE), polychlorinated biphenyls (PCBs), dioxins, and furans in eagle eggs. From 1994 to 1995, we collected partially incubated eggs at 19 of 43 occupied territories along the LCR and compared productivity and egg contaminants to values obtained in the mid-1980s. We found higher productivity at new nesting sites along the river, yet productivity at 23 older breeding territories remained low and was not different (p = 0.713) between studies. Eggshell thickness at older territories had not improved (p = 0.404), and eggshells averaged 11% thinner than shells measured before dichlorodiphenyltrichloroethane use. Decreases in DDE (p = 0.022) and total PCBs (p = 0.0004) in eggs from older breeding areas occurred between study periods. Productivity was not correlated to contaminants, but DDE, PCBs, and dioxin-like chemicals exceeded estimated no-effect values. Some dioxin-like contaminants in eggs were correlated to nest location, with highest concentrations occurring toward the river's mouth where productivity was lowest. Although total productivity increased due to the success of new nesting pairs in the region, egg contaminants remain high enough to impair reproduction at older territories and, over time, may alter productivity of new pairs nesting near the river's mouth.

Evaluation of the concentration of HCH, DDT, HCB, PCB and PAH in the sediments along the lower stretch of Hugli estuary, West Bengal, northeast India

Detailed analyses of persistent organic pollutants (POPs) such as hexachlorocyclohexane (HCH) isomers (HCHs), dichlorodiphenyltrichloro ethane (DDT) and its metabolites (DDTs), hexachlorobenzene (HCB) and congeners of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) in surface sediments from the coastal estuarine environment of West Bengal, northeast India allowed the evaluation of the contamination status, distribution and possible pollution sources. HCH, DDT, HCB, PCB and PAH were identified compounds in all the samples, whereas the concentrations of chlorinated pesticides (trans-eptachlorepoxide, dieldrin, endrin, metaoxychlor and mirex) were below the detection limits and were not of great concern. The pesticides did demonstrate markedly different distributions reflecting different agricultural and domestic usage in the region. The range of concentrations of HCH, HCB, DDT and PCBs in the sediments were 0.11–0.40, <0.05–0.98, 0.18–1.93 and 0.18–2.33 ng/g dry wt, respectively. Overall elevated levels of HCB, DDT and PCB were recorded at Babughat, a very closely located site of the metropolitan megacity Calcutta. Fluoranthene (flu) and pyrene (py), the dominant 4-ring PAHs, also showed an abrupt elevated concentrations at Babughat with values of 214 and 144 ng/g dry wt, respectively. Among the isomers and metabolites of HCH, DDT and PCB, α-HCH, pp′-DDT and PCB 101, PCB 118, PCB 153 and PCB 138 were found to be dominant. High ratios of metabolites of DDT to ΣDDTs reveal recent use of DDT in this coastal environment. Fluoranthene, pyrene, 1,2-benzo(a)anthracene and chrysene formed the dominant congeners out of 19 identified PAHs. The sources of contamination are closely related to human activities such as domestic and industrial discharge, automobile exhausts, street runoff, slum sewage, agricultural chemicals and soil erosion due to deforestation as well as atmospheric transport. This study is compared to other coastal and estuarine environments in India and abroad. The baseline data can be used for regular ecological monitoring, considering the industrial and agricultural growth around this important estuarine ecosystem.

Nonmalarial infant deaths and DDT use for malaria control.

Although dichlorodiphenyl trichloroethane (DDT) is being banned worldwide, countries in sub-Saharan Africa have sought exemptions for malaria control. Few studies show illness in children from the use of DDT, and the possibility of risks to them from DDT use has been minimized. However, plausible if inconclusive studies associate DDT with more preterm births and shorter duration of lactation, which raise the possibility that DDT does indeed have such toxicity. Assuming that these associations are causal, we estimated the increase in infant deaths that might result from DDT spraying. The estimated increases are of the same order of magnitude as the decreases from effective malaria control. Unintended consequences of DDT use need to be part of the discussion of modern vector control policy.