Inhaltsverzeichnis
Auswahl der wissenschaftlichen Literatur zum Thema „DDT (Insecticide) Environmental aspects“
Geben Sie eine Quelle nach APA, MLA, Chicago, Harvard und anderen Zitierweisen an
Machen Sie sich mit den Listen der aktuellen Artikel, Bücher, Dissertationen, Berichten und anderer wissenschaftlichen Quellen zum Thema "DDT (Insecticide) Environmental aspects" bekannt.
Neben jedem Werk im Literaturverzeichnis ist die Option "Zur Bibliographie hinzufügen" verfügbar. Nutzen Sie sie, wird Ihre bibliographische Angabe des gewählten Werkes nach der nötigen Zitierweise (APA, MLA, Harvard, Chicago, Vancouver usw.) automatisch gestaltet.
Sie können auch den vollen Text der wissenschaftlichen Publikation im PDF-Format herunterladen und eine Online-Annotation der Arbeit lesen, wenn die relevanten Parameter in den Metadaten verfügbar sind.
Zeitschriftenartikel zum Thema "DDT (Insecticide) Environmental aspects"
1
Kampango, Ayubo, Emma F. Hocke, Helle Hansson, Peter Furu, Khamis A. Haji, Jean-Philippe David, Flemming Konradsen, et al. "High DDT resistance without apparent association to kdr and Glutathione-S-transferase (GST) gene mutations in Aedes aegypti population at hotel compounds in Zanzibar." PLOS Neglected Tropical Diseases 16, no. 5 (May 16, 2022): e0010355. http://dx.doi.org/10.1371/journal.pntd.0010355.
Der volle Inhalt der QuelleAnnotation:
Global efforts to control Aedes mosquito-transmitted pathogens still rely heavily on insecticides. However, available information on vector resistance is mainly restricted to mosquito populations located in residential and public areas, whereas commercial settings, such as hotels are overlooked. This may obscure the real magnitude of the insecticide resistance problem and lead to ineffective vector control and resistance management. We investigated the profile of insecticide susceptibility of Aedes aegypti mosquitoes occurring at selected hotel compounds on Zanzibar Island. At least 100 adults Ae. aegypti females from larvae collected at four hotel compounds were exposed to papers impregnated with discriminant concentrations of DDT (4%), permethrin (0.75%), 0.05 deltamethrin (0.05%), propoxur (0.1%) and bendiocarb (0.1%) to determine their susceptibility profile. Allele-specific qPCR and sequencing analysis were applied to determine the possible association between observed resistance and presence of single nucleotide polymorphisms (SNPs) in the voltage-gated sodium channel gene (VGSC) linked to DDT/pyrethroid cross-resistance. Additionally, we explored the possible involvement of Glutathione-S-Transferase gene (GSTe2) mutations for the observed resistance profile. In vivo resistance bioassay indicated that Ae. aegypti at studied sites were highly resistant to DDT, mortality rate ranged from 26.3% to 55.3% and, moderately resistant to deltamethrin with a mortality rate between 79% to and 100%. However, genotyping of kdr mutations affecting the voltage-gated sodium channel only showed a low frequency of the V1016G mutation (n = 5; 0.97%). Moreover, for GSTe2, seven non-synonymous SNPs were detected (L111S, C115F, P117S, E132A, I150V, E178A and A198E) across two distinct haplotypes, but none of these were significantly associated with the observed resistance to DDT. Our findings suggest that cross-resistance to DDT/deltamethrin at hotel compounds in Zanzibar is not primarily mediated by mutations in VGSC. Moreover, the role of identified GSTe2 mutations in the resistance against DDT remains inconclusive. We encourage further studies to investigate the role of other potential insecticide resistance markers.
2
Guimarães, Raphael Mendonça, Carmen Ildes Rodrigues Fróes Asmus, and Armando Meyer. "DDT reintroduction for malaria control: the cost-benefit debate for public health." Cadernos de Saúde Pública 23, no. 12 (December 2007): 2835–44. http://dx.doi.org/10.1590/s0102-311x2007001200004.
Der volle Inhalt der QuelleAnnotation:
DDT is a persistent insecticide that was widely used in the world from the 1940s until the 70s, when it was banned in the United States and other countries. Most of its toxic effects are not observed in the acute forms, but particularly after chronic exposure. These long-term issues include reproductive effects, varying according to the time of life in which the individuals were exposed. The aims of the current study were to review the principal toxicological effects of DDT on reproduction, stratifying by physiological periods of exposure, and based on the magnitude of these effects, to discuss the cost-benefit relationship of reintroducing DDT with the specifically defined vector control criteria.
3
Dores, Eliana Freire Gaspar de Carvalho, Leandro Carbo, and Adley Bergson Gonçalves de Abreu. "Serum DDT in malaria vector control sprayers in Mato Grosso State, Brazil." Cadernos de Saúde Pública 19, no. 2 (April 2003): 429–37. http://dx.doi.org/10.1590/s0102-311x2003000200009.
Der volle Inhalt der QuelleAnnotation:
DDT was used intensively in vector control programs in Mato Grosso State until 1997. The present study aimed to determine DDT concentrations in blood samples from Brazilian National Health Foundation workers in Mato Grosso. Blood samples were analyzed from 41 sprayers, 20 drivers, and 14 unexposed workers, collected in June 1999 and October 2000 in two regions of the State (Sinop and Cáceres). Sprayers and drivers were occupationally exposed, and no significant differences were found in serum DDT levels between these two groups in either region. Likewise, no significant differences were found in p,p'DDE and total DDT levels between Cáceres and Sinop. However, p,p'DDT levels were higher in Sinop due to the intensive use of this insecticide in the region in recent years. The two regions together showed the following results: total DDT ranging from 7.50µg/L to 875.5µg/L (median = 135.5µg/L) for sprayers; from 34.5µg/L to 562.3µg/L (median = 147.7µg/L) for drivers; and from undetected to 94.8µg/L (median = 22.5µg/L) for unexposed workers.
4
Poniman, Tri Retnaningsih Soeprobowowati, and Muhammad Helmi. "Geospatial distributions of organochlorine insecticide in shallot agriculture land at Wanasari sub-district, Brebes regency, Central Java, Indonesia." E3S Web of Conferences 202 (2020): 06009. http://dx.doi.org/10.1051/e3sconf/202020206009.
Der volle Inhalt der QuelleAnnotation:
The organochlorine insecticide is a POPs compound that was monitored according to the Stockholm convention in 2003 because it can cause environmental damage and threaten human health. The study of the distribution of organochlorine insecticides on onion farms has been carried out in the village area in Wanasari sub-District and Brebes Regency. This study was conducted in March-June 2019, with the scope of soil sampling, organochlorine insecticide residue analysis, and spline interpolation. To determine the number of organochlorine insecticide residues using the SNI 06-6991.1-2004 method, while to determine the distribution pattern using the Spline interpolation method with the ArcGIS 10.4. In preparing geospatial residues, we use the ratio of the maximum residual limit (MRLs) of each organochlorine active ingredient. These research sites can be categorized as severe pollution of OCPs insecticides. In this study OCPs residues (Aldrin, Lindane, and Heptachlor, DDT, Endrin, and Dieldrin) can be found with concentrations above the MRLs requirements. OCPs residues with very high range characteristics are shown by Aldrin, DDT, Endrin, and Dieldrin each of more than 50% of the total observed land area. Point numbers six detected all OCPs residues were observed with concentrations exceeding MRLs.
5
Deb, Rinki, Rudra Pratap Singh, Prabhas Kumar Mishra, Lisa Hitchins, Emma Reid, Arti Manorama Barwa, Debanjan Patra, et al. "Impact of IRS: Four-years of entomological surveillance of the Indian Visceral Leishmaniases elimination programme." PLOS Neglected Tropical Diseases 15, no. 8 (August 9, 2021): e0009101. http://dx.doi.org/10.1371/journal.pntd.0009101.
Der volle Inhalt der QuelleAnnotation:
Background In 2005, Bangladesh, India and Nepal agreed to eliminate visceral leishmaniasis (VL) as a public health problem. The approach to this was through improved case detection and treatment, and controlling transmission by the sand fly vector Phlebotomus argentipes, with indoor residual spraying (IRS) of insecticide. Initially, India applied DDT with stirrup pumps for IRS, however, this did not reduce transmission. After 2015 onwards, the pyrethroid alpha-cypermethrin was applied with compression pumps, and entomological surveillance was initiated in 2016. Methods Eight sentinel sites were established in the Indian states of Bihar, Jharkhand and West Bengal. IRS coverage was monitored by household survey, quality of insecticide application was measured by HPLC, presence and abundance of the VL vector was monitored by CDC light traps, insecticide resistance was measured with WHO diagnostic assays and case incidence was determined from the VL case register KAMIS. Results Complete treatment of houses with IRS increased across all sites from 57% in 2016 to 70% of houses in 2019, rising to >80% if partial house IRS coverage is included (except West Bengal). The quality of insecticide application has improved compared to previous studies, average doses of insecticide on filters papers ranged from 1.52 times the target dose of 25mg/m2 alpha-cypermethrin in 2019 to 1.67 times in 2018. Resistance to DDT has continued to increase, but the vector was not resistant to carbamates, organophosphates or pyrethroids. The annual and seasonal abundance of P. argentipes declined between 2016 to 2019 with an overall infection rate of 0.03%. This was associated with a decline in VL incidence for the blocks represented by the sentinel sites from 1.16 per 10,000 population in 2016 to 0.51 per 10,000 in 2019. Conclusion Through effective case detection and management reducing the infection reservoirs for P. argentipes in the human population combined with IRS keeping P. argentipes abundance and infectivity low has reduced VL transmission. This combination of effective case management and vector control has now brought India within reach of the VL elimination targets.
6
Mbabazi, Jolocam. "DDT in indoor residual spraying: human health aspects." International Journal of Environmental Studies 70, no. 4 (August 2013): 663–64. http://dx.doi.org/10.1080/00207233.2013.813714.
Der volle Inhalt der Quelle
7
Tkachenko, I. V. "Hygienic assessment of potential ecotoxicological risk of the use of new insecticide spiromesifen in agriculture of Ukraine." Environment & Health, no. 4 (101) (November 2021): 62–67. http://dx.doi.org/10.32402/dovkil2021.04.062.
Der volle Inhalt der QuelleAnnotation:
Objective: The aim of our work was to study the potential ecotoxicological hazard of a new chemical from the class of tetramic and tetronic acid derivatives - the insecticide spiromesifen, taking into account its physico-chemical properties and impact on the environmental objects. Materials and methods: An assessment of the potential danger of spiromesifen use for ecosystems was carried out on the basis of the calculation of the ecotoxicological hazard (ecotox) by N.N. Melnikov’s method. The field studies were carried out in different agro-climatic zones of Ukraine. The treatment of vineyards and apple trees was carried out at the maximum consumption rates of spiromesifen. Results: According to the literary data and our research, it was found that in the soil-and-climatic conditions of Ukraine, the ecotoxicological risk, when using the new insecticide spiromesifen, is 10,000 times and 7,000 times low than the analogous characteristics of DDT. Ecotox abamectin is 154 times low than ecotox DDT. This makes preparations, based on these substances, more promising and competitive among other pesticides in agricultural use. We can conclude that spiromesifen does not pose a threat to terrestrial ecosystems and health of the population.
8
Collins, Emma L., Jody E. Phelan, Magdalena Hubner, Anton Spadar, Monica Campos, Daniel Ward, Holly Acford-Palmer, et al. "A next generation targeted amplicon sequencing method to screen for insecticide resistance mutations in Aedes aegypti populations reveals a rdl mutation in mosquitoes from Cabo Verde." PLOS Neglected Tropical Diseases 16, no. 12 (December 13, 2022): e0010935. http://dx.doi.org/10.1371/journal.pntd.0010935.
Der volle Inhalt der QuelleAnnotation:
Aedes mosquito vectors transmit many viruses of global health concern, including dengue, chikungunya and Zika. These vector-borne viral diseases have a limited number of treatment options, and vaccines vary in their effectiveness. Consequently, integrated vector management is a primary strategy for disease control. However, the increasing emergence and spread of insecticide resistance is threatening the efficacy of vector control methods. Identifying mutations associated with resistance in vector populations is important to monitor the occurrence and evolution of insecticide resistance and inform control strategies. Rapid and cost-effective genome sequencing approaches are urgently needed. Here we present an adaptable targeted amplicon approach for cost-effective implementation within next generation sequencing platforms. This approach can identify single nucleotide polymorphisms (SNPs) and small insertions and deletions (indels) in genes involved in insecticide resistance in Aedes aegypti mosquitoes. We designed and tested eleven amplicons, which included segments of the ace-1 (carbamate target), the Voltage-Gated Sodium Channel (vgsc; pyrethroids, DDT and organochlorines), and rdl (dieldrin) genes; thereby covering established knockdown resistance (kdr) mutations (e.g., S989P, I1011M/V, V1016G/I and F1534C), with the potential to identify novel ones. The amplicon assays were designed with internal barcodes, to facilitate multiplexing of large numbers of mosquitoes at low cost, and were sequenced using an Illumina platform. Our approach was evaluated on 152 Ae. aegypti mosquitoes collected in Cabo Verde, an archipelago with a history of arbovirus outbreaks. The amplicon sequence data revealed 146 SNPs, including four non-synonymous polymorphisms in the vgsc gene, one in ace-1 and the 296S rdl mutation previously associated with resistance to organochlorines. The 296S rdl mutation was identified in 98% of mosquitoes screened, consistent with the past use of an organochlorine compound (e.g., DDT). Overall, our work shows that targeted amplicon sequencing is a rapid, robust, and cost-effective tool that can be used to perform high throughput monitoring of insecticide resistance.
9
Galván-Portillo, Marcia, Carlos Jiménez-Gutiérrez, Luisa Torres-Sánchez, and Lizbeth López-Carrillo. "Food consumption and adipose tissue DDT levels in Mexican women." Cadernos de Saúde Pública 18, no. 2 (April 2002): 447–52. http://dx.doi.org/10.1590/s0102-311x2002000200009.
Der volle Inhalt der QuelleAnnotation:
This article analyzes food consumption in relation to levels of DDE (the principal metabolite of DDT) in the adipose tissue of 207 Mexican women residing in States with high and low exposure to DDT. Data on the women's dietary habits and childbearing history were obtained from a personal interview. Adipose tissue DDE levels were measured by gas-liquid chromatography and compared by analysis of variance (ANOVA) and multiple linear regression. Adipose tissue DDE levels increased significantly with age (p = 0.005) and residence in coastal areas (p = 0.002) and non-significantly with the consumption of onion, cauliflower, prickly pear, squash blossoms, sweet corn, broad beans, chili pepper sauce, ham, and fish. Even so, during breastfeeding there was a non-significant reduction in these levels. The findings suggest that certain foods serve as vehicles for DDE residues and confirm that breastfeeding is a mechanism for the elimination of this insecticide, which accumulates over the years in the human body.
10
Maunder, John W. "Strategic aspects of insecticide resistance in head lice." Journal of the Royal Society of Health 111, no. 1 (February 1991): 24–26. http://dx.doi.org/10.1177/146642409111100109.
Der volle Inhalt der QuelleDissertationen zum Thema "DDT (Insecticide) Environmental aspects"
1
Kantachote, Duangporn. "The use of microbial inoculants to enhance DDT degradation in contaminated soil." Title page, contents and abstract only, 2001. http://web4.library.adelaide.edu.au/theses/09PH/09phk165.pdf.
Der volle Inhalt der Quelle
2
Morodi, Thabiso John. "To spray or not to spray with DDT to control malaria : a case study in environmental ethics." Thesis, Stellenbosch : Stellenbosch University, 2003. http://hdl.handle.net/10019.1/53698.
Der volle Inhalt der QuelleAnnotation:
Thesis (MPhil)--Stellenbosch University, 2003.<br>Full text to be digitised and attached to bibliographic record.<br>ENGLISH ABSTRACT: This assignment is devoted to an in depth analysis of the pro- and the contra-positions
in the long-standing and costly debate about the question whether to spray with DDT
or not in the fight against malaria. I argue that the dilemma whether or not to spray
with DDT is born out of a political agenda, hype, exaggeration and misinformation of
the first order.
Radical environmentalists appear to insist that DDT is a principal contributor of
environmental degradation, and the major cause of death amongst wildlife and
humans. Worse still, many Western people seem to be under the impression that
mosquitoes cannot cause so much human misery as purported, and that malaria is
caused by some kind of plant form of life, or even a virus.
The proponents of DDT, on the other hand, appear to be convinced that DDT is a
saviour of humankind, and argue that the horrors associated with DDT are
exaggerated and baseless, as they are not backed by scientific inquiry. Proponents of
DDT also believe that anything that is overused may kill, even ordinary table salt.
Inthis assignment, both of these positions are scrutinized. On the basis of an historical
overview in Chapter I of the history of the use of DDT, and the emergence of the
debate about DDT in the wake of Rachel Carson's Silent Spring (1962), Chapter 2 is
devoted to an evaluation of seven basic arguments against the use of DDT, while in
Chapter 3 six arguments for the use of DDT are weighed. In Chapter 4 a resolution of
the dilemma is proposed in which a case is made for a limited use of DDT only for
indoor spraying of huts and houses against malaria mosquitoes until such time as a
less dangerous alternative for DDT is found that can be used as effectively in the fight
against malaria. As such, this case is informed by the strong moral conviction that we
cannot allow poor people of colour to die because of a general ban on the use of DDT.
Further research on this ethical debate is encouraged.<br>AFRIKAANSE OPSOMMING: Hierdie werkstuk is toegespits op 'n in-diepte analise van die pro- en kontra-posisies
in die voortslepende, asook duur debat oor die gebruik van DDT al dan nie in die
bekamping van Malaria. Ek argumenteer dat die dilemma rondom die vraag of DDT
gebruik moet word of nie, aangewakker word deur politieke agendas, sensasie,
oordrywing en foutiewe informasie van die eerste orde.
Radikale omgewingsgesindes dring oënskynlik daarop aan dat die gebruik van DDT
'n hoof-oorsaak is van die agteruitgang van die omgewing, asook 'n primêre oorsaak
van dood onder wild en mense. Erger nog, dit wil voorkom of heelwat Westerse
mense onder die indruk is dat muskiete nie werklik soveel menslike lyding kan
veroorsaak as wat voorgegee word nie, en dat malaria eerder veroorsaak word deur 'n
sekere soort plantvorm van lewe, of selfs deur 'n virus.
Die voorstaanders van DDT, aan die ander kant, is klaarblyklik oortuig dat DDT 'n
redder van die mensdom is, en argumenteer dat die gruwels wat geassosieer word met
DDT 'n grondelose oordrywing is, aangesien dit nie deur wetenskaplike ondersoek
gesteun word nie. Voorstaanders van DDT glo verder dat enige stof wat in oormaat
gebruik word, die dood kan veroorsaak, selfs gewone tafelsout.
In hierdie werkstuk word albei hierdie posisies krities bestudeer en bespreek. Op
grond van 'n historiese oorsig in Hoofstuk 1 oor die gebruik van DDT, en die ontstaan
van die debat oor DDT na aanleiding van Rachel Carson se Silent Spring (1962),
word Hoofstuk: 2 gewy aan 'n evaluasie van sewe basiese argumente teen die gebruik
van DDT, terwyl in Hoofstuk 3 ses argumente vir die gebruik van DDT oorweeg
word. In Hoofstuk 4 word 'n voorstel gemaak vir die resolusie van die dilemma deur
'n saak uit te maak vir die beperkte gebruik van DDT, nl. slegs vir binneshuise
gebruik in hutte en huise teen malaria-muskiete tot tyd en wyl 'n minder gevaarlike
alternatief vir DDT gevind word wat net so effektief sal wees in die stryd teen
malaria. As sulks word hierdie studie gerugsteun deur die sterk morele oortuiging dat
ons nie kan toelaat dat mense van kleur sterf as gevolg van 'n algemene verbod op die
gebruik van DDT nie.
Verdere navorsing oor hierdie etiese debat word aangemoedig.
3
Chan, Kit Yan. "Dietary exposure, human body loadings, and health risk assessment of persistent organic pollutants at two major electronic waste recycling sites in China." HKBU Institutional Repository, 2008. http://repository.hkbu.edu.hk/etd_ra/943.
Der volle Inhalt der Quelle
4
Mmualefe, Lesego Cecilia. "Sample preparation for pesticide analysis in water and sediments a case study of the Okavango Delta, Botswana." Thesis, Rhodes University, 2010. http://hdl.handle.net/10962/d1005006.
Der volle Inhalt der QuelleAnnotation:
This thesis presents a first ever extensive analysis of pesticides in water and sediments from the Okavango Delta, Botswana, employing green sample preparation techniques that require small volumes of organic solvents hence generating negligible volumes of organic solvent waste. Pesticides were extracted and pre-concentrated from water by solid phase extraction (SPE) and headspace solid phase microextraction (HS-SPME) while supercritical fluid extraction (SFE) and pressurized fluid extraction (PFE) were employed for sediments. Subsequent analysis was carried out on a gas chromatograph with electron capture detection and analytes were unequivocally confirmed by high resolution mass spectrometric detection. Hexachlorobenzene (HCB), trans-chlordane, 4,4′-DDD and 4,4′-DDE were detected after optimized HS-SPME in several water samples from the lower Delta at concentrations ranging from 2.4 to 61.4 μg L-1 that are much higher than the 0.1 μg L-1 maximum limit of individual organochlorine pesticides in drinking water set by the European Community Directive. The same samples were cleaned with ISOLUTE C18 SPE sorbent with an optimal acetone/n-hexane (1:1 v/v) mixture for the elution of analytes. No pesticides were detected after SPE clean-up and pre-concentration. HCB, aldrin and 4, 4‟-DDT were identified in sediments after SFE at concentration ranges of 1.1 - 30.3, 0.5 – 15.2 and 1.4 – 55.4 μg/g, respectively. There was an increase of pesticides concentrations in the direction of water flow from the Panhandle (point of entry) to the lower delta. DDE, fatty acids and phthalates were detected after PFE with optimized extraction solvent and temperature. The presence of DDT metabolites in the water and sediments from the Okavango Delta confirm historical exposure to the pesticide. However their cumulative concentration increase in the water-flow direction calls for further investigation of point sources for the long-term preservation of the Delta. The green sample preparation techniques and low toxicity solvents employed in this thesis are thus recommended for routine environmental monitoring exercises.
5
McDougal, Rebecca, and n/a. "DDT residue degradation by soil bacteria." University of Otago. Department of Microbiology & Immunology, 2007. http://adt.otago.ac.nz./public/adt-NZDU20070914.142931.
Der volle Inhalt der QuelleAnnotation:
1,1,1-trichloro-2,2-bis(4-chlorophenyl)-ethane (DDT) residues (DDTr) are widespread and persistent environmental contaminants, and have been classed as priority pollutants by the United Nations Environment Programme (UNEP). DDTr are potent endocrine disrupting molecules, and have been associated with reproductive abnormalities in juvenile alligators and rats. Microorganisms that metabolise DDTr both aerobically and anaerobically have been isolated and characterised. Bacteria that degrade DDTr aerobically typically utilise a dioxygenase to initiate degradative reactions through ring-hydroxylation, and convert DDTr to 4-chlorobenzoate without further degradation. Terrabacter sp. strain DDE-1 was isolated from DDTr-contaminated soil from Canterbury, New Zealand, and aerobically degrades 1,1-dichloro-2,2-bis-(4-chlorophenyl)-ethylene (DDE) to 4-chlorobenzoate, when grown in the presence of biphenyl (BP). The intermediates of degradation were inferred to be the end products of dioxygenase activity. Sequencing of a large linear plasmid, pBPH-1, from strain DDE-1 identified a cluster of genes with high levels of sequence similarity to BP-degradation genes from Rhodococcus spp. and Pseudomonas spp. This plasmid is lost at high frequency producing the plasmid-cured strain MJ-2, which has lost the ability to degrade BP or DDE. The aim of this study was to confirm that DDE-degradation in strain DDE-1 is encoded by the bph operon located on pBPH-1. No genetic systems to study gene function in either DDE-1 or MJ-2 could be developed using an array of broad-host range vectors. However, heterologous expression of the bph genes in Rhodococcus erythropolis strain TA422 was successful, with the recombinant strain TA425, obtaining the ability to utilise BP and DDE as a sole source of carbon and energy. DDE-1 was shown to convert indole to indigo, but MJ-2 could not, indicating that the biphenyl dioxygenase located on pBPH-1 is responsible for this activity. The bph genes from strain DDE-1 also conferred the ability to produce indigo from indole on strain TA425, confirming successful expression of the functional biphenyl dioxygenase in this strain. Despite several attempts to show quantitative degradation in strain TA425 using gas chromatography, the results were inconclusive Further analysis is needed to provide unequivocal evidence of DDE-degradation by strain TA425. Attempts to express the bph genes in rhizosphere-colonising bacteria, such a Rhizobium spp. or Pseudomonas spp., were unsuccessful, as evidenced by the inability to produce indigo, hence the lack of a functional biphenyl dioxygenase. However, RT-PCR did indeed indicate that P. aeruginosa strain Fin1 produced a bphA1 transcript, indicating that an error is occurring post-transcriptionally in these strains, to prevent production of the functional enzyme.
New Zealand has recently been shown to contain hotspots of DDTr-contamination. The second aim of this study was to determine the prevalence of DDTr-degrading bacteria and to gain insight into the types of bacteria that inhabit sites contaminated with DDTr. To investigate this, culture-dependent and culture-independent techniques were employed. Enrichment for DDTr-degrading bacteria yielded species of Rhodococcus and Ralstonia using DDTr-overlayer plate assays. The polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE) were used to amplify and analyse the 16S rDNA and 16S rRNA for the identification of dominant and active bacteria in soil samples. The results of this analysis identified bacteria such as Williamsia spp. and Gordonia spp. that degrade other types of pollutants. This analysis did not identify a predominance of Rhodococcus or Ralstonia spp., or other bacteria that have been shown to degrade DDTr. To identify ecologically relevant members of the bacterial communities in DDTr-contaminated soils, and potentially important metabolic pathways, identification of ring-hydroxylating dioxygenase (RHD) genes was performed. PCR and restriction fragment length polymorphism (RFLP) analysis were employed together with phylogenetic analyses. The results showed that the RHD genes identified, clustered separately to those genes previously characterised from cultivated bacteria. Among these genes, one phylogenetic group was most closely related to the dioxygenase genes from Ralstonia eutropha H850, which is potent PCB-degrading bacterium that possesses a dioxygenase with a wide substrate range for many types of heavily chlorinated, PCB congeners. The identification of a predominance of genes with similarity to phenyl-propionate dioxygenases has been not been recognised previously in soil studies.
6
Siu, Ka-yan Sky, and 蕭加欣. "DDT as a malarial vector control method and its potential risks to human reproductive health and neonatal development." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2007. http://hub.hku.hk/bib/B3972458X.
Der volle Inhalt der Quelle
7
Medeiros, Louise de Souza [UNESP]. "Toxidade aguda e risco ambiental do inseticida teflubenzuron para Daphnia magna, Lemna minor e Poecilia reticulata." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/86698.
Der volle Inhalt der QuelleAnnotation:
Made available in DSpace on 2014-06-11T19:22:23Z (GMT). No. of bitstreams: 0
Previous issue date: 2008-04-22Bitstream added on 2014-06-13T20:28:40Z : No. of bitstreams: 1
medeiros_ls_me_jabo.pdf: 334435 bytes, checksum: 9100b99eed78123f4f48b7158f17a02f (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>Os agrotóxicos aplicados nas áreas agrícolas podem ser carreados, por diversos mecanismos, até os corpos d’água da rede hidrográfica. Além disso, estes produtos são comumente utilizados na aqüicultura para o controle de parasitoses. O teflubenzuron (TFB) é um inseticida registrado em alguns países da Europa para o controle de parasitas de peixes. Os possíveis efeitos tóxicos e risco ambiental do TFB podem ser avaliados inicialmente em condições de laboratório por meio de testes de toxicidade aguda com organismos-teste eleitos internacionalmente. Os objetivos deste trabalho foram avaliar a toxicidade aguda e o risco de intoxicação ambiental do uso agrícola e em aqüicultura do TFB, com base nos valores de CE50 e CL50 estimados em testes com Daphnia magna, Lemna minor e Poecilia reticulata, utilizados como organismos bioindicadores. Os testes de ecotoxicidade aguda foram realizados de acordo com normas nacionais e internacionais para estas espécies. A CE50-48h estimada para D. magna foi 0,00026 mg.L- 1, o que caracteriza este inseticida como altamente tóxico para esta espécie. Para L. minor, a CE50-7d estimada foi 1.176,16 mg.L-1, e para P. reticulata CL50-96h, 2.707,87 mg.L- 1, que classificam o TFB como praticamente não-tóxico para estas duas espécies. Devido à alta toxicidade do TFB para daphnídeos, mesmo em pequenas contaminações, pode causar desequilíbrio na cadeia alimentar aquática. Para minimizar o risco ambiental, o TFB pode ser utilizado de forma controlada e diluído em quantidades restritas de água.<br>The pesticides used in agriculture areas can be transported to water bodies of the local hydrographic basin in several ways. Moreover, these chemicals are commonly used in aquaculture to fish parasite control. The teflubenzuron (TFB) is a registered insecticide in some European countries to this use. The possible effects of the TFB and environmental risk can be evaluated initially in laboratory conditions by tests of acute toxicity with internationally elected organisms. The objectives of this study were to evaluate the acute toxicity and the environmental risk due to agriculture and aquaculture use of TFB, based on the values of EC50 and LC50 estimated in tests with Daphnia magna, Lemna minor and Poecilia reticulata, internationally used as bioindicators organisms. The acute ecotoxicity tests were performed in accordance with national and international standards for these species. The EC50-48h estimated to D. magna was 0,00026 mg.L-1, which characterizes that as very highly toxic insecticide for this species. For L. minor, EC50-7d was estimated 1.176,16 mg.L-1, and P. reticulata LC50-96h, 2.707,87 mg.L-1, which classified the TFB as practically non-toxic to these species. Due to the high toxicity of the TFB to daphnids, even in little contamination, can cause a loss of equilibrium in the aquatic food chain. To minimize the environmental risk, the TFB can be used in a controlled way and diluted in limited quantities of water.
8
Souza, Jaqueline Pérola [UNESP]. "Toxicidade aguda e risco ambiental do diflubenzuron para Daphnia magna, Poecilia reticulata e Lemna minor na ausência e presença de sedimento." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/86694.
Der volle Inhalt der QuelleAnnotation:
Made available in DSpace on 2014-06-11T19:22:22Z (GMT). No. of bitstreams: 0
Previous issue date: 2008-03-07Bitstream added on 2014-06-13T19:27:38Z : No. of bitstreams: 1
souza_jp_me_jabo.pdf: 1313453 bytes, checksum: 4c61c83068fdecf5e8c6a9ee5b5f525e (MD5)<br>Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)<br>O inseticida diflubenzuron (DFB), comercializado como Dimilin®, é empregado em pisciculturas no tratamento de ecotoparasitoses em peixes. Este composto inibe a síntese de quitina, componente do exoesqueleto dos parasitas. A utilização deste inseticida se deve à sua baixa toxicidade aos peixes e eficácia no controle dos ectoparasitas. Porém, no ambiente aquático o DFB pode ser tóxico à espécies sensíveis e não-alvos, a concentração empregada no tratamento das ectoparasitoses é de 2 mg.L-1. Os objetivos deste estudo foram avaliar a toxicidade do DFB para as espécies de Daphnia magna, Poecilia reticulata e Lemna minor, classificar o produto quanto à sua toxicidade e risco ambiental e avaliar o efeito do sedimento na biodisponibilidade do DFB na água. Os organismos-teste foram submetidos a concentrações crescentes do inseticida em salas climatizadas do Laboratório de Ecotoxicologia da FCAV-UNESP. Os testes com D. magna foram realizados em volume de 10 mL a 20° C e cinco organismos neonatos por concentração, durante 48 horas na presença e ausência de sedimento. Os peixes (P. reticulata) foram expostos às concentrações do DFB por 96 horas em testes na presença e ausência de sedimento. O volume final foi de 3000 mL e cinco animais por concentração à 25° C. As plantas de L. minor foram expostas ao DFB por sete dias na presença e ausência de sedimento. O volume final foi de 100 mL e 12 frondes por concentração à 24° C. Os testes foram realizados com três réplicas incluindo o controle. As CE50-48h calculadas para D. magna foram de 0,56 μg.L-1 e 1,51 μg.L-1 na ausência e presença de sedimento respectivamente; as CL50-96h para P. reticulata foram 152,00 mg.L-1 e 277,83 mg.L-1 na ausência e presença de sedimento respectivamente; e as CE50-7dias para L. minor foram 459,50 mg.L-1 e 698,25 mg.L-1 na ausência e presença de sedimento respectivamente...<br>The insecticide diflubenzuron (DFB), marketed as Dimilin®, is used in fish farms to treat ectoparasites in fishes. This compound inhibits the chitin synthesis, exoskeleton component of the parasites. The use of this insecticide is due to its low toxicity for fish and effectiveness in the control of ectoparasites. However, the DFB in the aquatic environmental can be toxic to sensitive species and non-targed, the concentration used in the treatment of ectoparasites is 2 mg.L-1. The aims of this study were to evaluate the toxicity of the DFB for the species of Daphnia magna, Poecilia reticulata and Lemna minor, classify the product as to their toxicity and environmental risk and evaluate the effect of sediment on the bioavailability of the DFB in the water. The organisms-test were submitted to increasing concentrations of insecticide in air conditioned rooms of the Laboratory of Ecotoxicology FCAV-UNESP. Tests with D. magna were performed in volume of 10 mL at 20° C and five organisms neonates (6 and 24 hours of age) in each concentration, for 48 hours in the presence and absence of sediment. Fishes (P. reticulata) were exposed to concentrations of the DFB for 96 hours in tests in the presence and absence of sediment. The final volume was 3000 mL and five animals per concentration to 25° C. The plants of L. minor were exposed to the DFB for seven days in the presence and absence of sediment. The final volume was 100 mL and 12 fronds by concentration to 24° C. The tests were performed with three repetitions incluing the control. The EC50-48h estimeds for D. magna were 0.56 and 1.51 μg.L-1 in the absence and presence of sediment respectively; the LC50-96h for P. reticulata were 152.00 mg.L-1 and 277.83 mg.L-1 in the absence and presence of sediment respectively; and the EC50-7dias to L. minor were 459.50 mg.L-1 and 698.25 mg.L-1 in the absence and presence of sediment respectively...(Complete abstract, click electronic access below)
9
Medeiros, Louise de Souza. "Toxidade aguda e risco ambiental do inseticida teflubenzuron para Daphnia magna, Lemna minor e Poecilia reticulata /." Jaboticabal : [s.n.], 2008. http://hdl.handle.net/11449/86698.
Der volle Inhalt der QuelleAnnotation:
Orientador: Joaquim Gonçalves Machado Neto<br>Banca: Julio Vicente Lombardi<br>Banca: Robinson Antonio Pitelli<br>Resumo: Os agrotóxicos aplicados nas áreas agrícolas podem ser carreados, por diversos mecanismos, até os corpos d'água da rede hidrográfica. Além disso, estes produtos são comumente utilizados na aqüicultura para o controle de parasitoses. O teflubenzuron (TFB) é um inseticida registrado em alguns países da Europa para o controle de parasitas de peixes. Os possíveis efeitos tóxicos e risco ambiental do TFB podem ser avaliados inicialmente em condições de laboratório por meio de testes de toxicidade aguda com organismos-teste eleitos internacionalmente. Os objetivos deste trabalho foram avaliar a toxicidade aguda e o risco de intoxicação ambiental do uso agrícola e em aqüicultura do TFB, com base nos valores de CE50 e CL50 estimados em testes com Daphnia magna, Lemna minor e Poecilia reticulata, utilizados como organismos bioindicadores. Os testes de ecotoxicidade aguda foram realizados de acordo com normas nacionais e internacionais para estas espécies. A CE50-48h estimada para D. magna foi 0,00026 mg.L- 1, o que caracteriza este inseticida como altamente tóxico para esta espécie. Para L. minor, a CE50-7d estimada foi 1.176,16 mg.L-1, e para P. reticulata CL50-96h, 2.707,87 mg.L- 1, que classificam o TFB como praticamente não-tóxico para estas duas espécies. Devido à alta toxicidade do TFB para daphnídeos, mesmo em pequenas contaminações, pode causar desequilíbrio na cadeia alimentar aquática. Para minimizar o risco ambiental, o TFB pode ser utilizado de forma controlada e diluído em quantidades restritas de água.<br>Abstract: The pesticides used in agriculture areas can be transported to water bodies of the local hydrographic basin in several ways. Moreover, these chemicals are commonly used in aquaculture to fish parasite control. The teflubenzuron (TFB) is a registered insecticide in some European countries to this use. The possible effects of the TFB and environmental risk can be evaluated initially in laboratory conditions by tests of acute toxicity with internationally elected organisms. The objectives of this study were to evaluate the acute toxicity and the environmental risk due to agriculture and aquaculture use of TFB, based on the values of EC50 and LC50 estimated in tests with Daphnia magna, Lemna minor and Poecilia reticulata, internationally used as bioindicators organisms. The acute ecotoxicity tests were performed in accordance with national and international standards for these species. The EC50-48h estimated to D. magna was 0,00026 mg.L-1, which characterizes that as very highly toxic insecticide for this species. For L. minor, EC50-7d was estimated 1.176,16 mg.L-1, and P. reticulata LC50-96h, 2.707,87 mg.L-1, which classified the TFB as practically non-toxic to these species. Due to the high toxicity of the TFB to daphnids, even in little contamination, can cause a loss of equilibrium in the aquatic food chain. To minimize the environmental risk, the TFB can be used in a controlled way and diluted in limited quantities of water.<br>Mestre
10
Souza, Jaqueline Pérola. "Toxicidade aguda e risco ambiental do diflubenzuron para Daphnia magna, Poecilia reticulata e Lemna minor na ausência e presença de sedimento /." Jaboticabal : [s.n.], 2008. http://hdl.handle.net/11449/86694.
Der volle Inhalt der QuelleAnnotation:
Orientador: Joaquim Gonçalves Machado Neto<br>Banca: Julio Vicente Lombardi<br>Banca: Robinson Antonio Pitelli<br>Resumo: O inseticida diflubenzuron (DFB), comercializado como Dimilin®, é empregado em pisciculturas no tratamento de ecotoparasitoses em peixes. Este composto inibe a síntese de quitina, componente do exoesqueleto dos parasitas. A utilização deste inseticida se deve à sua baixa toxicidade aos peixes e eficácia no controle dos ectoparasitas. Porém, no ambiente aquático o DFB pode ser tóxico à espécies sensíveis e não-alvos, a concentração empregada no tratamento das ectoparasitoses é de 2 mg.L-1. Os objetivos deste estudo foram avaliar a toxicidade do DFB para as espécies de Daphnia magna, Poecilia reticulata e Lemna minor, classificar o produto quanto à sua toxicidade e risco ambiental e avaliar o efeito do sedimento na biodisponibilidade do DFB na água. Os organismos-teste foram submetidos a concentrações crescentes do inseticida em salas climatizadas do Laboratório de Ecotoxicologia da FCAV-UNESP. Os testes com D. magna foram realizados em volume de 10 mL a 20° C e cinco organismos neonatos por concentração, durante 48 horas na presença e ausência de sedimento. Os peixes (P. reticulata) foram expostos às concentrações do DFB por 96 horas em testes na presença e ausência de sedimento. O volume final foi de 3000 mL e cinco animais por concentração à 25° C. As plantas de L. minor foram expostas ao DFB por sete dias na presença e ausência de sedimento. O volume final foi de 100 mL e 12 frondes por concentração à 24° C. Os testes foram realizados com três réplicas incluindo o controle. As CE50-48h calculadas para D. magna foram de 0,56 μg.L-1 e 1,51 μg.L-1 na ausência e presença de sedimento respectivamente; as CL50-96h para P. reticulata foram 152,00 mg.L-1 e 277,83 mg.L-1 na ausência e presença de sedimento respectivamente; e as CE50-7dias para L. minor foram 459,50 mg.L-1 e 698,25 mg.L-1 na ausência e presença de sedimento respectivamente...(Resumo completo, clicar acesso eletrônico abaixo)<br>Abstract: The insecticide diflubenzuron (DFB), marketed as Dimilin®, is used in fish farms to treat ectoparasites in fishes. This compound inhibits the chitin synthesis, exoskeleton component of the parasites. The use of this insecticide is due to its low toxicity for fish and effectiveness in the control of ectoparasites. However, the DFB in the aquatic environmental can be toxic to sensitive species and non-targed, the concentration used in the treatment of ectoparasites is 2 mg.L-1. The aims of this study were to evaluate the toxicity of the DFB for the species of Daphnia magna, Poecilia reticulata and Lemna minor, classify the product as to their toxicity and environmental risk and evaluate the effect of sediment on the bioavailability of the DFB in the water. The organisms-test were submitted to increasing concentrations of insecticide in air conditioned rooms of the Laboratory of Ecotoxicology FCAV-UNESP. Tests with D. magna were performed in volume of 10 mL at 20° C and five organisms neonates (6 and 24 hours of age) in each concentration, for 48 hours in the presence and absence of sediment. Fishes (P. reticulata) were exposed to concentrations of the DFB for 96 hours in tests in the presence and absence of sediment. The final volume was 3000 mL and five animals per concentration to 25° C. The plants of L. minor were exposed to the DFB for seven days in the presence and absence of sediment. The final volume was 100 mL and 12 fronds by concentration to 24° C. The tests were performed with three repetitions incluing the control. The EC50-48h estimeds for D. magna were 0.56 and 1.51 μg.L-1 in the absence and presence of sediment respectively; the LC50-96h for P. reticulata were 152.00 mg.L-1 and 277.83 mg.L-1 in the absence and presence of sediment respectively; and the EC50-7dias to L. minor were 459.50 mg.L-1 and 698.25 mg.L-1 in the absence and presence of sediment respectively...(Complete abstract, click electronic access below)<br>Mestre
Bücher zum Thema "DDT (Insecticide) Environmental aspects"
1
Canada. Commercial Chemicals Evaluation Branch. DDT: Scientific justification. Ottawa, Ont: Environment Canada, 1997.
Den vollen Inhalt der Quelle finden
2
Rinella, Joseph F. Persistence of the DDT pesticide inthe Yakima River Basin, Washington. (Reston, VA): U.S. Dept. of the Interior, U.S. Geological Survey, 1993.
Den vollen Inhalt der Quelle finden
3
Rinella, Joseph F. Persistence of the DDT pesticide in the Yakima River Basin, Washington. [Reston, VA]: U.S. Dept. of the Interior, U.S. Geological Survey, 1993.
Den vollen Inhalt der Quelle finden
4
The true story of DDT, PCB, and Dioxin. Wrocław: Wydawnictwo Chemiczne, 2005.
Den vollen Inhalt der Quelle finden
5
Roger, Bate, and Liberty Institute (New Delhi, India), eds. When politics kills: Malaria and the DDT story. New Delhi: Liberty Institute, 2000.
Den vollen Inhalt der Quelle finden
6
Rogowski, David. Verifying 303(d) DDT/DDE and Dieldrin listings for the upper Yakima River. [Olympia, Wash.]: Washington State Dept. of Ecology, 2000.
Den vollen Inhalt der Quelle finden
7
Serdar, Dave. DDT in Osoyoos Lake fish. Olympia, WA: Washington State Dept. of Ecology, Environmental Assessment Program, Watershed Ecology Section, 1998.
Den vollen Inhalt der Quelle finden
8
The role of science in environmental policy making: Hearing before the Committee on Environment and Public Works, United States Senate, One Hundred Ninth Congress, first session, September 28, 2005. Washington: U.S. G.P.O., 2008.
Den vollen Inhalt der Quelle finden
9
Peterschmidt, Mark. Lower Okanogan DDT PCB: Water quality implementation plan (detailed implementation plan). Yakima, WA: Washington State Dept. of Ecology, 2006.
Den vollen Inhalt der Quelle finden
10
Peterschmidt, Mark. Lower Okanogan DDT PCB: Water quality implementation plan (detailed implementation plan). Yakima, WA: Washington State Dept. of Ecology, 2006.
Den vollen Inhalt der Quelle findenBuchteile zum Thema "DDT (Insecticide) Environmental aspects"
1
Wurster, Charles F. "EDF, Barely an Organization, Getting Its Act Together." In DDT Wars. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190219413.003.0010.
Der volle Inhalt der QuelleAnnotation:
The late 1960s and early 1970s was a world of increasing political unrest on many fronts. In January 1969, Richard Nixon replaced Lyndon Johnson as president. Public support for the war in Vietnam was diminishing and there were widespread antiwar demonstrations. Environmental awareness and concerns were rapidly increasing. Air and water pollution were increasingly severe. A huge oil spill dumped 100,000 barrels of crude oil onto the beaches of Santa Barbara, California. The Cuyahoga River in Ohio caught fire. Students buried automobiles on college campuses. Lake Erie could no longer support fish. The great whales were being killed in record numbers. People were apprehensive about pesticides. The Bald Eagle, national symbol, was disappearing. The first Earth Day was launched in 1970. Responding to this public outcry, the National Environmental Policy Act passed Congress almost unanimously and became law on January 1, 1970; the Clean Air Act became law in 1970, the Clean Water Act in 1972, and the Endangered Species Act in 1973; and the Federal Insecticide, Fungicide and Rodenticide Act was rewritten in 1972. Rachel Carson’s Silent Spring had appeared in 1962 and generated a sizable public reaction, but pesticide policies had changed very little by 1970. This was the milieu in which EDF sought to pursue its goals of a national ban on DDT and the development of environmental law. Reaching those goals would require a much more substantial organization than EDF was in 1969; at that time it was little more than a board of trustees with plenty of ideas but no staff, no office, and almost no money. Most of those trustees were going about their normal lives with EDF concerns more like a hobby than a profession. Their dedication was strong and very real, but a strategic game plan was barely in sight. There were additional impediments when compared with today’s world. Forty-five years ago communications barely resembled what we have now. Most television sets were black-and-white with small screens and large bulky bodies, although color TV was arriving slowly. There were no computers or cell phones.
2
Wurster, Charles F. "Time to Go After the Feds." In DDT Wars. Oxford University Press, 2015. http://dx.doi.org/10.1093/oso/9780190219413.003.0012.
Der volle Inhalt der QuelleAnnotation:
By the fall of 1969 we knew we had to challenge pesticide regulation by the federal government if we were to ultimately prevail against DDT, but we did not know how to do it. We had the science well in hand and knew how to present it, with literally hundreds of scientists prepared to testify within their areas of expertise. We did not have the organizational structure to launch such an effort at the federal level, however, and we were certainly short of money. At about that time Joseph L. Sax, then the leading proponent of the development of environmental law at the University of Michigan Law School, suggested that we contact the newly founded Center for Law and Social Policy (CLASP), a public-interest law firm in Washington, DC. Joe was a member of the CLASP board. He insisted that DDT was in violation of the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA) and that the U.S. Department of Agriculture (USDA) was not enforcing FIFRA. I therefore called and talked at length with James W. Moorman (Fig. 7.1), attorney for CLASP, describing the DDT problem and proposed action against USDA. “If we are going to do this, then you are going to come down here and help me put the case together,” said Jim firmly. That was not music to my ears: I had other things I needed to do, but shortly I was on my way to Washington. CLASP was in a rundown part of Washington, and my “housing” consisted of sleeping on an old mattress in their dusty attic. But we got to work and wrote a petition to USDA in about a week. The petition was a formal legal request that the FIFRA registrations for DDT be canceled. The petition also requested that USDA suspend the registrations while it was considering their cancellation. We had no illusions that USDA would grant our request, but it was Jim’s advice that we go to USDA for administrative relief before seeking cancellation and suspension from the courts.
3
"Factors That Influence Toxicity." In Environmental Toxicology, edited by Sigmund F. Zakrzewski. Oxford University Press, 2002. http://dx.doi.org/10.1093/oso/9780195148114.003.0009.
Der volle Inhalt der QuelleAnnotation:
The more species are removed from each other in evolutionary development, the greater is the likelihood of differences in response to toxic agents. One obvious difference that affects toxicity is the size of the organisms. Much less toxin is needed to kill a small insect than a considerably larger mammal (everything else being equal). In addition, there is an inverse relationship between the weight of an animal and its surface area; the smaller the animal, the larger its surface area per gram of weight. Thus, the weight ratio of a human being (70 kg) to a rat (200 g) is 350, but the surface area ratio of a human being to a rat is only 55. Roughly, the surface area of an animal (S) can be calculated as follows: S(m2) = weight (kg)2/3/10. This type of calculation is important when one is considering the selective eradication of an uneconomical species, such as certain insects, by spraying an area with insecticide. The goal is to control the insects without harming wildlife, livestock, and human beings. Other factors, such as the rate of percutaneous absorption, also have to be considered. For instance, it has been shown that DDT (dichlorodiphenyltrichloroethane) is about equally toxic to insects and mammals when given by injection, yet when applied externally it is considerably more toxic to insects. This toxicity is due not only to the difference of the surface area:- body weight ratio, but also to the fact that the chitinous exoskeleton of the insect is more permeable to DDT than unprotected mammalian skin (1). Of course, in real-life situations (i.e., outside the laboratory), most mammalian skin is covered by fur, which gives the animals additional protection. The foregoing discussion is not meant to imply that unrestricted spraying with pesticides (especially chlorinated hydrocarbons, which are fat-soluble and poorly biodegradable) is environmentally sound. Problems with their use include lack of selectivity among insect species; leaching into watersheds and groundwater; and bioaccumulation in the food chain. These problems will be discussed in detail in Chapter 11. Metabolic-pathway differences among species may provide another rationale for achieving selective toxicity