Production Of DDT Research Articles

Degree of phenyl chlorination of DDT-related compounds as potential molecular indicator for industrial DDT emissions

The pesticide DDT (1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene) and its degradates are among the most persistent and abundant organochlorine contaminates in the environment, and DDT is still being produced in several Asian countries. In this study, we report for the first time on the detection of DDT-related compounds with one additional or missing chlorine atom at the phenyl group (DDX±Cl) in sediment and soil samples taken in the vicinity of former and current DDT production sites. These congeneric compounds most likely originate from production residues disposed of into the environment. In order to ensure an adequate identification and quantification of this novel organic pollutant group, individual DDX±Cl were synthesized as reference compounds by simulating an impure production of DDT in the laboratory. In contrast to DDX±Cl with (chloro)alkyl moieties, DDX±Cl with (chloro)alkenyl moieties cannot be unambiguous assigned by gas-chromatographic/mass spectrometric (GC/MS) fragmentation and elution orders. The occurrence of DDX±Cl in environmental samples allows to draw conclusions about the purity of the production process in the associated production sites. Moreover, they potentially can serve as molecular indicators to differentiate between industrial DDT emissions and insecticidal applications of DDT. This hypothesis has yet to be confirmed by further research.

Global trends in the production and use of DDT for control of malaria and other vector-borne diseases

BackgroundDDT was among the initial persistent organic pollutants listed under the Stockholm Convention and continues to be used for control of malaria and other vector-borne diseases in accordance with its provisions on acceptable purposes. Trends in the production and use of DDT were evaluated over the period 2001–2014.ResultsAvailable data on global production of DDT showed a 32% decline over the reporting period, from 5144 to 3491 metric tons of active ingredient p.a. Similarly, global use of DDT, for control of malaria and leishmaniasis, showed a 30% decline over the period 2001–2014, from 5388 metric tons p.a. to 3772 metric tons p.a. India has been by far the largest producer and user of DDT. In some countries, DDT is used in response to the development of resistance in malaria vectors against pyrethroid and carbamate insecticides. Some other countries have stopped using DDT, in compliance to the Convention, or in response to DDT resistance in malaria vectors. Progress has been made in establishing or amending national legal measures on DDT, with the majority of countries reportedly having measures in place that prohibit, or restrict, the production, import, export and use of DDT. Limitations in achieving the objectives of the Stockholm Convention with regard to DDT include major shortcomings in periodic reporting by Parties to the Stockholm Convention, and deficiencies in reporting to the DDT Register.ConclusionGlobal production and global use of DDT have shown a modest decline since the adoption of the Stockholm Convention.

DDT Paradox: Bouwman et al. Respond

In our commentary (Bouwman et al. 2011), we presented our centrist point of view on DDT, briefly, that despite DDT’s known protective effects against malaria, there is a need to eventually eliminate its use due, in part, to growing concerns about DDT’s human health impacts. How this can be misrepresented as anti-DDT by Tren and Roberts is simply astounding. The reference to “isolated studies” on health aspects of DDT by Tren and Roberts has no basis. Of the 22 epidemiological studies from 2009 that we cited, 12 showed that DDT was significantly associated with some condition. We also notice that their “thousands of studies” is not substantiated by references. The evidence we presented is consistent with that of Eskenazi et al. (2009) and justifies our recommendation to invoke precaution. Tren and Roberts refer to the recent Convention of the Parties of the Stockholm Convention (COP-SC) and the DDT Expert Group’s report to the COP-SC (UNEP 2011b). The report stated that In certain settings, there is a continued need for DDT for malaria vector control, until locally appropriate and cost-effective alternatives are deployed for a sustainable transition away from DDT. (UNEP 2011b) Moreover, the COP-SC report (UNEP 2011a) stated that “there was broad support for the recommendation by the DDT expert group that DDT was needed in some countries for disease vector control.” It is simply impossible to construe this statement as “anti-DDT.” Most, if not all, of the actions considered by Tren and Roberts as “anti-DDT” can be aligned with a centrist point of view, because most countries involved are Parties to the SC. The COP-SC final report (UNEP 2011a) stated that “there was broad agreement regarding the need to combat malaria and to reduce and eventually eliminate the production and use of DDT.” Regarding the World Health Organization (WHO) assessment of DDT (WHO 2011) quoted in their letter, Tren and Roberts fail to add the qualification included in the same paragraph, namely, In some areas, the exposures in treated residences have been higher than potential levels of concern. Efforts are needed to implement best practices to protect residents in treated households from exposures arising from IRS [indoor residual spray]. Of particular concern would be women of childbearing age who live in DDT IRS-treated dwellings and transfer of DDT and DDE to the fetus in pregnancy and to the infant via lactation. This is what we concluded in our commentary (Bouwman et al. 2011). WHO procedures recommend the removal of furniture and food from houses to be sprayed, as well as a no-entry period (Najera and Zaim 2002). This implies an explanatory obligation toward the households why this has to be done. Nowhere in our commentary did we actually argue “that households should be informed about” the possible effects of DDT, as purported by Tren and Roberts. We maintain however, that the use of any insecticide in IRS raises ethical issues. This requires further investigation; the implications for IRS are yet unknown. We defined our position as centrist because we acknowledge the role of DDT in malaria vector control as well as the urgency to move away from DDT once suitable, safe, and sustainable alternatives are in place. Our position is based on available evidence; invoking precaution, we suggest, is the best approach to address the paradox.

Production and use of DDT containing antifouling paint resulted in high DDTs residue in three paint factory sites and two shipyard sites, China

This study provides the first intensive investigation of Dichlorodiphenyltrichloroethanes (DDT) distribution in typical paint factories and shipyards in China where DDT containing antifouling paint were mass produced and used respectively. DDTs were analyzed in soil, sludge and sediment samples collected from three major paint factories and two shipyards. The results showed that the total DDTs concentrations detected in paint factory and shipyard sites ranged from 0.06 to 8387.24 mg kg −1. In comparison with paint factory sites, the shipyard sites were much more seriously contaminated. However, for both kinds of sites, the DDTs level was found to be largely affected by history and capacity of production and use of DDT containing antifouling paint. (DDE + DDD)/DDT ratios indicated that DDT containing antifouling paint could serve as important fresh input sources for DDTs. It can be seen that most samples in shipyards were in ranges where heavy contamination and potential ecological risk were identified.

DDT Controversy in the Debate on Safe and Effective Malaria Vector Control

The expert group of the Stockholm Convention on DDT utilised for malaria vector control met in Geneva on 10th to 12th November 201'3 The goal of this meeting was to assess the current situation of DDT use and alternatives to DDT, and to make new recommendations for disease vector control. The Committee will report to the fifth meeting of the Conference of the Parties (COP5), to be held on 25th to 29th April 2011 in Geneva. Even though the Stockholm Convention seeks and supports a phase-out of the insecticide, the use of DDT in malaria vector control is increasing. In this regard and alongside the DDT expert group meeting, a controversial panel discussion took place in Geneva on 12th November 201'3 This event provided a platform for invited experts from various fields and with different backgrounds to discuss new developments related to DDT used in malaria vector control as well as alternative solutions. Representatives from governments, international organizations, research institutions, the industry and NGOs debated on the pros and cons of DDT and alternatives for effective malaria control. The debate on DDT use in malaria vector control was an interesting exchange and provided new insights such as information about non-chemical alternatives, decreasing production of DDT, and industry’s efforts in pushing alternatives to DDT. Most panellists highlighted the importance of enhancing the application of available sustainable alternatives to DDT and pushing forward Integrated Vector Management (IVM) in the fight against malaria. However, some panelists also argued that DDT is effective and that negative health impacts are not proven.

DDT in Malaria Control: Roberts and Tren Respond

Herren and Mbogo’s critique of our response (Tren and Roberts 2010) to van den Berg (2009) is lacking in substance. In their letter, they attack our work by characterizing our advocacy for using DDT to control malaria as a distraction from larger malaria control issues. These authors apparently discount the fact that some African countries are presently making highly effective use of DDT to reduce both malaria deaths and malaria infections. Countries that use DDT benefit from its spatial repellent action that stops mosquitoes from entering houses and transmitting disease, and no alternative insecticide does this (Roberts and Tren 2010). In addition, Herren and Mbogo apparently do not understand that our advocacy is consistent with that exhibited by the malaria control community, with hundreds signing a petition to prevent DDT elimination through Stockholm Convention negotiations. If DDT had been eliminated, countries presently using DDT would have been deprived of its benefits for protecting health and saving lives. Herren and Mbogo claim that our response to van den Berg’s commentary (van den Berg 2009) was fixated on DDT, in lieu of addressing the larger issues of what should be done to control malaria. In our letter (Roberts and Tren 2010), we addressed what we considered to be an attack on DDT use. How could we have responded without addressing the issues in van den Berg’s commentary? Herren and Mbogo mischaracterize our position vis-a-vis DDT and alternative insecticides by asserting that we are reducing the malaria control debate to a simplistic equation of malaria or DDT. In fact, we have a public record of supporting the use of insecticide-treated nets and the use of alternative insecticides for malaria control. However, we have repeatedly emphasized that, for obvious reasons, insecticide-treated nets are not the only solution for malaria control. In fact, we object to a theme of nets and nets alone as much as we would object to a theme of DDT and DDT alone. Basically, there is no single-solution approach to malaria control. All tools are needed—not just those that are currently in vogue. Herren and Mbogo state that they are fully aware that malaria is a worse outcome than possible health effects of DDT. We agree with them and appreciate their willingness to admit this, because their admission opposes published speculations that DDT might be causing more harm than good (Chen and Rogan 2003). Herren and Mbogo conclude that we “do more to fuel those ‘interminable debates’ [DDT or no DDT for malaria control] than to meaningfully inform decisions that will save people’s lives.” It seems that these authors ignore the fundamental fact that we do not elaborate on alternative approaches to malaria control because the alternatives are not presently under threat of elimination. The alternatives are being used and should continue to be used, but the future is far less certain for DDT. Advocacy saved DDT from being eliminated during the original negotiations for the Stockholm Convention, and lives are being saved and diseases prevented as a consequence. The idea that the threat is over and that DDT is now available to those countries making effective use of it is wrong. The Stockholm Convention Secretariat is now planning to stop all production of DDT in 2017 and eliminate it entirely from use in malaria control programs in 2020 (UN Environment Program 2010). The Stockholm Convention Secretariat plans to prevent future uses of DDT, even though there is no cost-effective replacement for DDT. Given these circumstances, Herren and Mbogo should expect the interminable debates to become even more polemic in the future. As for the big issues of what should be done to control malaria, our position is clear: Decisions should be based on scientific evidence of what actually works, on local circumstances, and on what proves to be the most cost-effective in terms of reducing disease and preventing human deaths.

Contaminant exposure and reproductive success of ospreys (Pandion haliaetus) nesting in Chesapeake Bay regions of concern.

The Chesapeake Bay osprey population has more than doubled in size since restrictions were placed on the production and use of DDT and other toxic organochlorine contaminants in the 1970s. Ospreys are now nesting in the most highly polluted portions of the Bay. In 2000 and 2001, contaminant exposure and reproduction were monitored in ospreys nesting in regions of concern, including Baltimore Harbor and the Patapsco River, the Anacostia and middle Potomac rivers, and the Elizabeth River, and a presumed reference site consisting of the South, West, and Rhode rivers. A "sample egg" from each study nest was collected for contaminant analysis, and the fate of eggs remaining in each nest (n = 14-16/site) was monitored at 7- to 10-day intervals from egg incubation through fledging of young. Ospreys fledged young in regions of concern (observed success: 0.88-1.53 fledglings/active nest), although productivity was marginal for sustaining local populations in Baltimore Harbor and the Patapsco River and in the Anacostia and middle Potomac rivers. Concentrations of p,p'-DDE and many other organochlorine pesticides or metabolites, total PCBs, some arylhydrocarbon receptor-active PCB congeners and polybrominated diphenyl ether congeners, and perfluorooctanesulfonate were often greater in sample eggs from regions of concern compared to the reference site. Nonetheless, logistic regression analyses did not provide evidence linking marginal productivity to p,p'-DDE, total PCBs, or arylhydrocarbon receptor-active PCB congener exposure in regions of concern. In view of the moderate concentrations of total PCBs in eggs from the reference site, concerns related to new and emerging toxicants, and the absence of ecotoxicological data for terrestrial vertebrates in many Bay tributaries, a more thorough spatial evaluation of contaminant exposure in ospreys throughout the Chesapeake may be warranted.

Anaerobic-aerobic biodegradation of DDT (dichlorodiphenyl trichloroethane) in soils.

) is a pesticide that belongs to the group of organochlorines. It has beenextensively used since the Second World War all over the world and, even though its useis banned or restricted in many countries because of its deleterious effects, it is stillcommonly found in the environment, especially in the soil, due to its strong adsorption tosolid particles, which results in a great persistency (EPA, 1986). Some investigationshave reported that the DDT present in the soil can be degraded in two years, while othershave found that the process can take from fifteen to twenty years or more (Alexander,1994).The degradation products of DDT are mainly the dechlorination products DDE and DDD.The pathway can be DDT → DDE → DDD, or from DDT to DDD directly. These routeshave not been completely established, even after 40 years of studies (Wayland et al.,1991). In anaerobic marine sediments DDE is readily dechlorinated to DDMU (Quensenet al., 1998).In less developed countries, the use of DDT still continues in order to control diseasessuch as malaria and dengue (Wayland et al., 1991; Cebrian, 1998). So far, no chemicalcompound has been found that brings together DDT’s properties and effectiveness. InMexico, the use of DDT is higher than in any other Latin American country (PAHO,1994). Mexico used about 1000 tons of DDT in 1992 (Sharpe, 1995). The production ofDDT in Mexico is mostly for its own use. Though production has diminished since 1970,it has remained stable since 1985 (Lopez-Carrillo et al., 1996). In a study carried out inthe state of Veracruz in Mexico, DDT and DDE were determined in the adipose tissue ofpeople. These compounds were present in all the cases analyzed and the highest levelswere found in a suburban zone. Average DDT concentration was 24.82 mg/kg, veryhigh compared to the results in other countries (Waliszewski et al., 1995).In recent years, there has been renewed research interest in DDT, since it has beenassociated with several health problems, including the increased risk of breast cancer inwomen and alterations in reproductive functions in men (Cebrian, 1998).DDT is a chlorinated organic compound that is highly resistant to degradation bybiological, photolithical and chemical means, given that its molecular structure containschlorinated aliphatic and aromatic structures that impart great chemical stability.Because of this, DDT is a recalcitrant, toxic, persistent pollutant (Kannan et al., 1992).This explains the current interest in developing bioremediation processes for thiscompound.Current bioremediation processes typically use aerobic bacteria to degrade petroleum andother chemical wastes by oxidation of the compounds. However, it has been observedthat anaerobic systems are often more capable of degrading chlorinated pollutants byreductive dechlorination (Leahy and Brown, 1994). Some compounds, such aspolychlorinated biphenyls (PCBs) can be initially dechlorinated and partially degraded by

News Briefs: All production and use of DDT should be banned worldwide by 2007

News Briefs: All production and use of DDT should be banned worldwide by 2007

DDT, DDD, and DDE contamination of sediment in the Newark Bay estuary, New Jersey

Two hundred and forty-six surface and buried sediment samples from Newark Bay, New Jersey, and its major tributaries (Passaic River, Hackensack River, Newark Bay, Arthur Kill, Elizabeth River, and Kill Van Kull) were assayed for p,p′-dichlorodiphenyltrichloroethane (p,p′-DDT), p,p′-dichlorodiphenyldichloroethane (p,p′-DDD), and p,p′-dichlorodiphenylchloroethylene (p,p′-DDE) between February 1990 and March 1993. Chronological profiles in sediments from pre-1940 to the present were determined by radioisotope activities of 210Pb and 137Cs. The concentrations of these chemicals were compared to National Oceanic and Atmospheric Administration (NOAA) benchmark sediment values (Long and Morgan 1991). The objectives were to (a) determine the spatial and temporal distributions of DDT compounds in sediments, (b) identify possible sources, and (c) assess the potential for sediment toxicity within the estuary. Mean concentrations in surface sediments in individual waterways ranged from 5 to 473 μg/kg for p,p′-DDT, 18 to 429 μg/kg for p,p′-DDD, and 5 to 111 μg/kg for p,p′-DDE. A regional background mean concentration of approximately 100–300 μg/kg Σp,p′-DDT (sum of p,p′-DDT, p,p′-DDD, and p,p′-DDE) was measured in surface sediments throughout the estuary, with the exception of the Arthur Kill, where mean concentrations exceeded 700 μg/kg. The elevated concentrations found in recently deposited surface sediments in the Arthur Kill may be due to the presence of ongoing sources. The highest concentrations in buried sediments occurred in the lower Passaic River at depths corresponding to historical deposits from 1940 to 1970, the peak time period for production and usage of DDT in the United States. Comparisons to NOAA benchmark sediment toxicity values indicate that p,p′-DDT, p,p′-DDD, and p,p′-DDE concentrations in surface sediments may pose a potential hazard to fish, shellfish, and other benthic and demersal organisms in some portions of the estuary, particularly in the upper and lower Arthur Kill.

DDT in the biosphere: where does it go?

The worldwide pattern of movement of DDT residues appears to be from the land through the atmosphere into the oceans and into the oceanic abyss. Calculations based on the fragmentary data available on. rates of movement and sizes of various pools of DDT residues lead to the conclusion that concentrations in the atmosphere and in the mixed layer of the oceans lag by only a few years behind the amounts of DDT used annually throughout the world. A model suggests that maximum concentrations of DDT residues occurred in air in 1966 and will occur in the mixed layer of the oceans in 1971. The biota probably contains in total less than 1/30 of 1 year's production of DDT during the mid-1960's, a very small amount in proportion to the total potentially available. The reason for the biota's failure to absorb larger quantities and to be affected much more severely is unclear. The analysis suggests that mere good fortune has protected man and the rest of the biota from much higher concentrations, thus emphasizing the need to determine the details of the movement of DDT residues and other toxins through the biosphere and to move swiftly to bring world use of such toxins under rational control based on firm knowledge of local and worldwide cycles and hazards.

The Effect of Various Condensing Agents and Inert Solvents in the Production of DDT

At the present time almost all DDT, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, produced commercially is made by a process based on the classic and original synthesis of Zeidler.(4) This method consists of condensing chloral or chloral hydrate with chlorobenzene through the action of concentrated sulfuric acid or oleum. Several isomers are possible. According to Gunther,(2) technical DDT produced by the Brothman continuous process contains 70% of the p,p'-isomer, 18% of the o,p'-isomer, and 6% of the o,o'-isomer, the balance being ash, volatile, and unidentified material. Little mention has been made in the literature of new methods of synthesizing DDT. A student at the Fresno State College(') is said to have used zinc chloride in place of sulfuric acid as a condensing agent, but this has not yet been confirmed by other reports. Rueggeberg and Torrans(3) have condensed chloral hydrate and chlorobenzene through the action of chlorosulfonic acid to produce a 77% yield of DDT. In order to obtain satisfactory yields of DDT by the condensation of chloral with chlorobenzene through the action of sulfuric acid, a large excess of acid and chlorobenzene are necessary. The object of this paper is to investigate the use of other condensing agents and the use of inert solvents. Zinc chloride, thionyl chloride, sulfuryl chloride, phosphoric acid, and phosphorus pentoxide were tried as condensing agents. Inert solvents such as carbon tetrachloride, chloroform, carbon disulfide, and skelly solvent were used as solvents for the DDT during its preparation using sulfuric acid as a condensing agent.

A Study of the Production of DDT

THOMAS T. CASTONGUAY and RICHARD L. FERM Chemical Engineering Department, University of Kansas. Although considerable private development has been carried out on the preparation of DDT, 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane, little data on the production of this compound has appeared in the literature. The classic and original synthesis by Zeidler'12) in 1874 is used as a basis for present day commercial production. Directions for the preparation of DDT on a laboratory scale by the condensation of chloral, or chloral hydrate, with chlorobenzene using sulfuric acid as a catalyst have been given by Zeidler,'12) Miiller,'10) Hughes, (7,8) Iris and Leyva,(9) Bailes, (1) and Darling.(8) Rueggeberg and Torrans' have used chlorosulfonic acid in place of sulfuric acid. In 1943 Brothman and Barish(2) designed a pilot plant for the continuous production of DDT using chloral, oleum, and an excess of chlorobenzene. Several different isomers are possible. According to Gunther,5) technical DDT produced by the Brothman continuous process contains 70% of the p,p'-isomer, 18% of the o,p'-isomer, and 6% of the o,o'-isomer, the balance being ash, volatile, and unidentified material. The composition of technical DDT has been studied by Haller and co-workers.(6)