Amount Of DDT Research Articles

Гигиеническая оценка риска для здоровья населения, обусловленного контаминацией пищевых продуктов хлорорганическими пестицидами

Accumulation of anthropogenic contaminants in food is one of the by-products of economic and other activities practiced by humankind. This study aimed to analyze the public health risks associated with ingestion of organochlorine pesticides (HCH, DDT) widely used in agriculture. The risk assessment was enabled by Nutri-prof software package; the data collected covered actual dietary patterns of 1798 people (823 men and 975 women) aged 18 to 65. Assessment of the level of contamination of food with organochlorine pesticides relied on the results of analysis of 16510 food product samples belonging to various groups. Bread and bread products, vegetables and melons, potatoes, milk and dairy products were shown to be the source of HCH in the amounts causing the greatest non-cancerogenic risk associated therewith. The list of products delivering the largest amounts of DDT into the body and thus posing the greatest non-cancerogenic risk associated therewith includes bread and bread products, vegetables and melons, meat and meat products, milk and dairy products. With the median DDT and HCH concentrations factored in, the highest joint cancerogenic risk level a person may be exposed to reaches the third range, which is acceptable for occupational groups. From the age of 45, consumption of bread and bread products leads to the related endocrine system risks growing beyond background levels, and from 65, these risks, considered negligible up to this age, become moderate. The results of this study support effectiveness of the sanitary and epidemiological food safety control system; the considered methodological approach to risk assessment allows making timely management decisions that account for the nature of work and dietary peculiarities.

PCDD/F formation during thermal desorption of p,p'-DDT contaminated soil.

Thermal treatment of polychlorinated biphenyls (PCB) contaminated soil was shown in earlier work to generate polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF). In this study, the PCDD/F were studied arising during the remediation of p,p'-DDT contaminated soil by thermal desorption. Three kinds of soil (sandy, clayey and lateritic soil) were tested to investigate the effect of soil texture on PCDD/F formation. Those soils were artificially polluted with p,p'-DDT, obtaining a concentration level of 100mg/kg. Thermal desorption experiments were conducted for 10min at 300°C in an air atmosphere. The total concentration of PCDD/F generated for three soils were 331, 803 and 865ng/kg, respectively, and TeCDD and TeCDF were dominant among all PCDD/F congeners. After thermal desorption, the total amount of PCDD/F generated both in soil and in off-gas correlated positively with the amount of DDT added to soil. In addition, a possible pathway of the formation of PCDD/F was presented.

Synthesis of Cu–Sb–S nanocrystals: insight into the mechanism of composition and crystal phase selection

In this work, Cu–Sb–S nanocrystals (NCs) with various compositions and crystal structures are realized by only tuning the amount of 1-dodecanethiol (DDT). When the DDT amount is 3.6, 5.5, 20.5, and 25.6 mmol, pure tetragonal Cu3SbS4, cubic Cu12Sb4S13, orthorhombic CuSbS2, and orthorhombic Cu3SbS3 NCs are respectively obtained. Systematic investigations demonstrate that different amounts of DDT are responsible for formation of the different compositions and crystal structures of the initial Cu2−xS seeds, which results into the formation of various Cu–Sb–S NCs. This reaction path is further verified by control experiments from successful preparation of Cu–Sb–S NCs comparable to that of the as-prepared ones directly from the reaction of Sb2S3 NCs with Cu2−xS seeds. The current study not only provides a facile and economical way to synthesize high-quality Cu–Sb–S NCs, but also opens a new route for preparation other I–V–VI multicomponent chalcogenides NCs, such as Cu–Bi–S systems.

Assessment of pollution in the Bizerte lagoon (Tunisia) by the combined use of chemical and biochemical markers in mussels, Mytilus galloprovincialis

In order to assess the environmental quality of the Bizerte lagoon (Tunisia), biomarker and contaminant levels were measured in Mediterranean mussels (Mytilus galloprovincialis) from five selected sites. Persistent organic pollutants (POPs) were quantified in whole body and enzyme activities such as acetylcholinesterase (AChE), catalase (CAT) and glutathione S-transferase (GST) in gills. Despite the relatively low levels of organic contaminants, the selected biomarkers responded differently according to the pollution level at the different sites. GST and AChE activities were correlated with the amount of DDTs in mussel tissues. These two enzymatic activities were also correlated to temperature and pH. No significant difference was observed for CAT activity. Principal component analysis showed a clear separation of sampling sites in three different assemblages which is consistent with POP body burden in mussels. Our results confirmed the usefulness of combining biomarker and chemical analyses in mussels to assess chemical pollution in the Bizerte lagoon.

Controllable synthesis of silver and silver sulfide nanocrystals via selective cleavage of chemical bonds

A one-step colloidal process has been adopted to prepare silver (Ag) and silver sulfide (Ag2S) nanocrystals, thus avoiding presynthesis of an organometallic precursor and the injection of a toxic phosphine agent. During the reaction, a layered intermediate compound is first formed, which then acts as a precursor, decomposing into the nanocrystals. The composition of the as-obtained products can be controlled by selective cleavage of S–C bonds or Ag–S bonds. Pure Ag2S nanocrystals can be obtained by directly heating silver acetate (Ag(OAc)) and n-dodecanethiol (DDT) at 200 ° C without any surfactant, and pure Ag nanocrystals can be synthesized successfully if the reaction temperature is reduced to 190 ° C and the amount of DDT is decreased to 1 ml in the presence of a non-coordinating organic solvent (1-octadecene, ODE). Otherwise, the mixture of Ag and Ag2S is obtained by directly heating Ag(OAc) in DDT by increasing the reaction temperature or in a mixture of DDT and ODE at 200 ° C. The formation mechanism has been discussed in detail in terms of selective S–C and Ag–S bond dissociation due to the nucleophilic attack of DDT and the lower bonding energy of Ag–S. Interestingly, some products can easily self-assemble into two- or three-dimensional (2D or 3D) highly ordered superlattice structures on a copper grid without any additional steps. The excess DDT plays a key role in the superlattice structure due to the bundling and interdigitation of the thiolate molecules adsorbed on the as-obtained nanocrystals.

Facile Synthesis of Mn-Doped ZnS Nanocrystals and Determination of Critical Temperature for Lattice Diffusion Process

High-quality Mn:ZnS doped nanocrystals (d-dots) with photoluminescence (PL) quantum yield (QY) of 50-70% have been synthesized based on nucleation-doping strategy by choosing 1-dodecanethiol (DDT) as the capping ligand. Controlling the growth of small-sized MnS core nanoclusters was successfully achieved by changing the injection temperature of sulfur precursor, the growth time of MnS nuclei, and the amount of DDT. Furthermore, MnS/ZnS core/shell d-dots with a diffusion layer at the interface between the MnS core and the ZnS shell were fabricated through an overcoating of the ZnS shell layer on the presynthesized MnS core nanoclusters. The resulting monodisperse d-dots exhibited spherical shape with a zinc-blende crystal structure. The critical temperature for lattice diffusion of Mn ions in the ZnS host lattice was determined to be about 260 degrees C by annealing the presynthesized and purified Mn:ZnS d-dots.

Concentrations of DDTs and Enantiomeric Fractions of Chiral DDTs in Agricultural Soils from Zhejiang Province, China, and Correlations with Total Organic Carbon and pH

Dichlorodiphenyltrichloroethanes (DDTs) are persistent organic pollutants that were widely used in China, especially eastern China, as insecticides. This work investigated the concentration, dissipation, and volatilization of DDTs and enantiomeric fractions (EFs) of o,p'-DDD and o,p'-DDT in agricultural soils collected in 2006 from 58 sites in Zhejiang province. Correlations between DDT residues and soil properties were assessed to determine the effect of soil properties on the environmental attenuation of DDTs. High concentrations and detection frequencies were found for DDTs in agricultural soils in the region even though large-scale use of DDTs was banned over 20 years ago. The amount of DDTs was about 485 tons in the upper 20 cm of the soil column of cropland in the province in 2010, with a dissipation half-life of ~9 years. The mass flux of DDTs was 43 ng m(-2) h(-1), which corresponds to emissions of 7.6 tons with an emission factor of 1.6% in 2006. The low p,p'-DDT/p,p'-DDE ratios and high o,p'-DDT/p,p'-DDT ratios suggest that there were no recent inputs of DDTs but fresh application of dicofol, which contains DDT (o,p'-DDT in particular) impurities. The significant positive correlation between concentrations of DDTs and total organic carbon content (TOC) indicates the distribution of DDTs fit a typical "secondary distribution" pattern. DEVrac of o,p'-DDD, which is defined as the absolute value of EFs subtracted from 0.5, was significantly related with most of the physicochemical and microbial soil properties. The most significant correlation is that between DEVrac of o,p'-DDD and soil pH (p < 0.001), indicating that the soil pH plays a key role in enantioselective residues of DDTs.

Synthesis of CdS, ZnS, and CdS/ZnS Core/Shell Nanocrystals Using Dodecanethiol

We report a new route to synthesize high quality zinc blende CdS and ZnS nanocrystals in noncoordinating solvent 1-octadecene, using dodecanethiol (DDT) molecules as both the sulfur source and surface capping ligands. Different reaction temperatures and Cd(Zn)/DDT molar ratios were tested to optimize the synthesis conditions. Absorption photoluminescence (PL) spectroscopy, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) pattern, and transmission electron microscopy (TEM) were used to characterize assynthesized nanocrystals. The narrow half width at the half-maximum on the long wavelength side of the firstexcitonic absorption peak and TEM images demonstrated nearly monodisperse size distributions of asprepared CdS, ZnS, and CdS/ZnS core/shell nanocrystals. Only trap emissions of the nanocrystals were detected when the amount of DDT was excessive, this came from the strong quenching effect of thiol groups on the nanocrystal surfaces. After overcoating with ZnS shells, band-gap emissions of CdS nanocrystals were partially recovered.

Levels of Agricultural Pesticides in Sediments and Irrigation Water from Tono and Vea in the Upper East of Ghana

Water and sediment samples were taken from selected irrigation dams located at Tono and Vea in the Upper East Region of Ghana and analyzed for organic pesticides using gas chromatography. Sixteen organic residues were identified of which thirteen had at least some trace concentrations ranging from 0.001 to 25.4 µg/L. It was found in the laboratory that the concentrations of DDT, BHC and heptachlor were above the upper limited recommended by WHO and the concentrations of DDT in both reservoirs were higher than 20 times the recommended limits. High concentrations of DDT were found in the water samples while the other two residues were identified in the sediments. The high DDT concentration in water was due to 1) the initial amount of DDT applied and the period in the reservoirs, 2) a half-life of 350 days suggested that much of the DDT originally used was not destroyed if applied less than this period, 3) its low solubility in water did not allow for dissolution and subsequent dispersal in water; 4) the indiscriminate uses of DDT for fishing as confirmed by the local people The high DDT level suggested that the water is not safe for many aquatic organisms and even humans. Generally the levels of these organic residues suggested that the dams have been polluted due to human activities such as farming and the unorthodox method of fishing. Therefore, steps should be taken to reduce the levels of DDT concentrations to preserve the aquatic life in the dams.

PERSISTENT ORGANIC POLLUTANTS: Melting Glaciers Release Frozen Toxicants

The melting of glacial ice that formed in the middle of the twentieth century may be a source of a cocktail of persistent, bioaccumulative toxic substances that can threaten human health and the environment, according to a study by Christian Bogdal, a postdoctoral research fellow at the Swiss Federal Institute of Technology, Zurich, and colleagues in the 1 November 2009 issue of Environmental Science & Technology. Their findings, along with those of a handful of other studies, suggest the release of toxics once bound within glaciers may be a little-recognized consequence of ongoing climate change. The Swiss team analyzed sediment samples taken from Lake Oberaar, a glacier-fed lake in central Switzerland. They measured sediment levels of several pollutants that would have entered the lake over the period 1953–2006 and compared the measurements with those from three lower-altitude Swiss lakes that aren’t glacier fed. The substances analyzed included 17 dioxins and furans, 18 polychlorinated biphenyls (PCBs), 10 synthetic musk compounds, DDT and two of its transformation products (DDE and DDD), 4 additional organochlorine pesticides (hexachlorobenzene, hexachlorocyclohexane, dieldrin, and heptachlor epoxide) and their transformation products, and polychlorinated naphthalenes. The Lake Oberaar and lower-altitude samples reflected a generally consistent pattern of increased influx of the compounds into the lakes from the 1950s through a peak in the 1960s–1970s, followed by a decrease to relatively low levels in the 1980s and 1990s. The exception was musk compounds, whose sediment influx was fairly steady from the 1950s to the mid-1990s. These patterns parallel the widespread increase in production and use of these substances from the 1950s through the 1970s, and the subsequent decline (except in the case of musk compounds) as concerns about toxic effects often resulted in restrictions or bans on use. These patterns also mesh with the premise that the primary source of the sediment toxics to that point was deposition of airborne pollutants generated in urban, industrial, and agricultural areas. Beginning in the late 1990s, however, the influx of all the compounds into Lake Oberaar—but not the lower-altitude lakes—increased moderately to sharply. In some cases, the new peak influxes were 2–5 times higher than the 1960s–1970s peaks. These increases coincide with a total reduction in Alpine glacier volume of about 12% between 1999 and 2008, according to a report by Daniel Farinotti and colleagues in the August 2009 issue of Global and Planetary Change. About one-quarter of that reduction occurred following the unusually hot summer of 2003. Bogdal and colleagues hypothesize that the sources of the later contaminant influxes they observed likely were not distant, because production and use of these chemicals had decreased substantially. Instead, they conclude the glacial meltwater was the source. Studies they are conducting at Lake Oberaar and elsewhere support this hypothesis, says Bogdal. The evidence to date suggests the release of these and other persistent toxics, such as lead and mercury, may be a concern for many glaciated settings. Among areas of potential concern, say Bogdal and other experts in this field, are locations in the Arctic region, Antarctica, the Alps, the Himalayas, and the Caucasus, Andes, Rocky, Cascade, and Sierra Nevada mountain ranges. “Melting of glaciers is releasing a huge amount of water containing dangerous contaminants used in the past,” says Roberta Bettinetti, an assistant professor of freshwater ecology at Italy’s University of Insubria. “Now these pollutants can contaminate great basins even at low altitudes where water is used for drinking and fishing purposes.” In the October 2008 issue of Chemosphere, Bettinetti and colleagues reported on their study of the toxic effects of melting glaciers on biota of two southern Alpine lakes. They found that the amount of DDT and its metabolites released by melting glacial ice increased the concentrations in lake mussels and fish above the threshold considered safe for human consumption. Silvana Galassi, a professor of ecology at the University of Milan and coauthor of that report, recommends implementation of monitoring to identify areas where mitigation, such as limiting fish consumption or avoiding disturbance of sediments, may be warranted.

Accumulation of DBPs in Human Breast Milk

ISEE-0538 Background and Objectives: All over the world the authorities are challenged to balance the risk presented by microbial pathogens and DBPs resulted from the disinfectant used to destroy them from drinking water. Unfortunately these toxic DBPs can be transferred from mother to infant via breastfeeding. The aim of this study was to determine these DBPs in water from distribution systems and its accumulation in human milk. Methods: DBPs such as THMs and HAAs from water were analyzed over the last 3 years on GC-ECD using HS-extraction. Starting with 2008, milk samples from 58 nursing mothers were collected and analyzed for these DBPs on GC-ECD-MS after separating the lipid content from milk. An interview was held with each of the mother based on a standard WHO questionnaire. A comparison study were performed between mother living in urban area using disinfected water and mothers living in rural area using untreated water from house well. Results: The most commonly determined DBPs from water were THMs with an average of TTHMs between 85 μg × l−1 −21 μg × l−1, higher values being measured in summer seasons. The HAAs concentration was notably lower, with an average of THAAs at 13 μg × l−1. In breast milk collected from women living in urban area we detected DBPs, with an average at 23 pg/lipid for ΣTHMs and 1.8 pg/lipid for ΣHAAs. The value of daily intake of these DBPs from mother's milk by children was calculated based on the formula of USEPA. Conclusions: It was observed that in the case of women from rural area the concentration of DBPs was extremely low, almost nonexistent but considerable amounts of DDT were detected in their case. The following results have been obtained of daily intake of these compounds: 0.0008–0.0011 for ΣHAAs (mg × kg−1), 0.09–0.0021 ΣTHMs (mg × kg−1) and 0.072–0.0095 for ΣDDT (mg × kg−1).

Biology in the Chemical Industry: Scientific Approaches to the Problem of Insecticide Resistance, 1920s–1960s

This paper examines the intensification of research and development into organic and inorganic insecticidal compounds during the first half of the twentieth century, and the involvement of biologists within the insecticide industry. It attempts to trace the history of resistance research, while highlighting the role of the biologist within the chemical industry prior to the biotechnology era.Specifically, this paper looks at the reaction of two private companies on the finding of resistance to insecticides: Geigy and Bayer. Geigy, who discovered the insecticidal properties of DDT, initially attributed resistance to ineffective application of insecticides or variable external factors. Only after doubling of the amount of DDT had failed to achieve the desired result, did the company undertake a biological research programme in an effort to understand resistance from a biological— as opposed to chemical— perspective. Ultimately, scientists both inside and outside the industry accepted the biological fact of resistance and the realisation that chemical control by itself would not be able to circumvent an insect population's ability to tolerate lethal dosages of chemical insecticides. The shift in the insecticide industry's approach to biological research is instructive in understanding how industry can approach complex issues.

Determination of DDT in model samples by using solid-phase extraction and indirect competitive enzyme immunoassay

Two-step indirect competitive enzyme immunoassay of DDT has been developed. The limit of detection and limit of quantification were 0.3 nmol l−1 and 4.2 nmol l−1, respectively. To shorten the analysis time, the one-step enzyme immunoassay has been developed by replacing anti-DDT antibody with the complex anti-DDT antibody-HRP. The anti-DDT antibody-HRP conjugate was prepared by periodate method. A concentration of the preparation was 1.9 mg·ml−1 and molar ratio Px/IgG was 1.87. The detection limit of the one-step ELISA reached 0.3 nmol l−1, but the sensitivity of assay was very poor. The two-step enzyme immunoassay of DDT has been adapted for the chemiluminescent detection of the complex antigen-antibody. The detectability of chemiluminescent ELISA was comparable with that of chromogenic ELISA. A limited number of the artificially contamined samples have been tested. All samples were prepared by solid-phase extraction by using the commercial Agilent Zorbax SPE C18 columns. A background was observed in most tested samples. The recoveries obtained from the analysis of DDT spikes reached values between 89.0–161.0%, and 81.5–111.6% at standard addition 50 μg·kg−1, and 200 μg·kg−1, respectively. The overestimated amounts of DDT were determined in spinach and nectarines at standard addition 50 μg·kg−1.

Can a Pollution Event be Detected Using a Single Biological Effects Monitoring Method?

The trends of malformation prevalence in embryos of dab, Limanda limanda, in the southern North Sea after the year 1990 mirrored the drop in major pollutants in the rivers draining into the German Bight. Despite this general decline, we detected a pollution event in the southern North Sea in winter 1995/1996 employing the prevalence of malformations in pelagic dab embryos as an indicator. An abrupt rise in malformation prevalence in the embryos of dab, corresponded to a dramatic increase in DDT levels in parent fish from the same area, indicating a hitherto unnoticed introduction of considerable quantities of DDT into the system.

Assessment of DDT accumulation by brine shrimp (Artemia salina) from filtered water and sewage effluent

The accumulation of a chlorinated pesticide, DDT, from filtered water and from sewage effluent by brine shrimp (Artemia salina) was investigated in a short‐term laboratory ecosystem. During 24‐h of contamination, Artemia was found to rapidly accumulate significant amounts of DDT from two aqueous environments with DDT ranging from 0.1 μg mL‐1 to 2.0 μg mL‐1. The highest levels of DDT in the body of Artemia were found in the 2.0 μg mL‐1 treatment group to be 1.24 μg g‐1 and 0.42 μg g‐1 (dry wt basis) in filtered water and in sewage effluent, respectively. A decreasing survival of the nauplii was observed with increasing DDT concentrations in both aqueous environments. Percentages of DDT accumulation by Anemia in both aqueous environments were also affected by the increase of DDT concentrations.

Estimation of DDT availability to DDT-degrading bacterium in soil by a direct extraction method of bacterial cells

The availability of DDT to a DDT-degrading bacterium, 26f in autoclaved soil was estimated as DDT amount in the bacterial cell fraction extracted directly from soil using a dispersion-centrifugation method. Recovery of the cells from soil was in the range of 30% to 65%. The bioavailable amount of DDT, expressed as the sum of DDT and its major metabolite DDD, was 0.25 nmol after one day of incubation when the soil contained 2.94 nmol as total.

Distribution of DDTs in the Sediment of Lake Biwa

An investigation was carried out to determine the residual tendency of DDT and its derivatives in the sediment of Lake Biwa, Japan, where the banning of DDT took effect some 15 years ago. Of the two basins shaping Lake Biwa, the frequency of detection of DDT was higher in the Northern Basin than in the Southern Basin. In the Southern Basin, the area of DDT detection was more confined than that of DDE detection. Therefore, it is reasonable to assume that DDT has been decomposing more rapidly in the Southern Basin than in the Northern Basin. Based on the profile obtained for the vertical distribution of DDTs, it can be inferred also that the amount of DDT and DDE flowing in from land has been decreasing in the past years. DDT has hardly been decomposing into DDE at the deeper part of the Lake.

Levels of organochlorine insecticides in human blood from Ahmedabad (rural), India.

Assessments of human exposure to persistent organochlorine insecticides (OCI) through biological monitoring offers a profound criteria to evaluate the magnitude of potential health risk, if any, due to use of these chemicals. Residues of these chemicals especially DDT and HCH have been identified and reviewed in man and his environment from different parts of the world however, by comparison very high levels of DDT and its metabolites have been reported in human body fat, blood and milk samples in India. Since there is a definite relationship between the amount of DDT and its residues in blood and those present in human fat depot, blood can be easily be used for assessing the total body burden of persistent OCI in various populations. In view of fragmentary reports on the levels of DDT and HCH in human blood samples from India which categorically pertain to the general population of urban areas like Delhi and Lucknow. The authors attempted to provide a database on residues of DDT and HCH including other cyclodiene compounds, e.g. heptachlor, heptachlor epoxide, aldrin, oxygchlordane, HCB and dieldrin in blood samples collected from general population of Ahmedabad (rural) area.

Occupational exposure to DDT among mosquito control sprayers

DDT, a broad action insecticide whose use is restricted or banned in most industrialized countries is still often used for vector control in many tropical and developing countries. Despite the fact that DDT is accumulative and persistant in the ecosystem use of such substitutes as malathion or propoxur is not popular because these increases costs by 3.4 to 8.5 fold. As such DDT is economically attractive to poorer countries. As far as can be ascertained no systemic poisoning has resulted from occupational exposure to DDT. Due to the large particle size, the amount of DDT inhaled by workers is far less than the amount reaching exposed portions of skin. As such occupational exposure is mainly dermal or tropical. Occupational exposure to DDT studies have been done before. The present study is an analysis of some characteristics, (i.e. age, body size, relationship between plasma vitamin A and DDE levels, and smoking habits), of occupational exposure to DDT among spraymen in a Zimbabwe population.

Computer Simulation of Ddt Distribution in Palos Verdes Shelf Sediments

Prior to the imposition of effective source‐control measures in 1970, large quantities of DDT were discharged to the Los Angeles County municipal sewer system and, subsequently, to the Pacific Ocean. A fraction of this material accumulated among sediments of the Palos Verdes shelf. While the bulk of the DDT lies 10–40 cm below the sediment surface, its fate may be affected by future wastewater‐treatment decisions at the Joint Water Pollution Control Plant (JWPCP), Los Angeles County's 385‐mgd treatment plant. To assess the impact of impending JWPCP secondary treatment requirements on shelf sediment quality (processes that potentially affect the distribution of chemical tracers among those sediments, including background sedimentation rate), contributions from effluent‐related solids, sediment mixing, and diffusive transport were incorporated in mathematical models. Model projections of surface‐sediment quality at the most heavily contaminated sites are sensitive to projected effluent solids concentrations...