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At least 163 records · Page 9Linked to original sources

Unmasking the truth behind endocrine disruptors.

The increase in reproductive cancers and developmental problems over the past 70 years has led researchers to suspect environmental influences as a root cause. Evidence from wildlife and laboratory studies suggests that exposure to endocrine disruptors (EnDs) may be the cause. An EnD is a foreign substance or mixture that alters the function of the endocrine system. They can be found in food, water, soil, or air. Research into their possible role provides an opportunity to decrease modifiable risk factors.

Air Pollution↗

[Conservation of tap water in metallo-plastic bags: observed modifications and possible health risks].

Conservation of tap water kept in soft plastic bags and stocked at different temperatures (20, 37 and 55 degrees C) and its health incidences were studied over one year by samples taken at regular intervals. Pollutants generated were studied by investigating the consequences of the choice of the plastic and of the aseptic agent used at different temperatures versus the length of the period of contact. Microbiological, chemical, and physico-chemical characteristics reported here showed the existence of an exchange between the contents and the container. The presence of two toxic substances indicates that one should be careful when using inadequate material. This is a matter to think about without further speculation.

Environmental Health↗

Survey of phthalate pollution in arable soils in China.

The problem of pollution by phthalates is of global concern due to their widespread occurrence, toxicity and endocrine disruption properties. The contamination by phthalates such as dimethyl phthalate (DMP), diethyl phthalate (DEP), di-n-butyl phthalate (DBP) and di(2-ethylhexyl) phthalate (DEHP) in 23 arable soils throughout China was investigated to evaluate the present pollution situation. The survey results demonstrated that phthalates were ubiquitous pollutants in soils in China. The total concentrations of phthalates differed from one location to another, and ranged from 0.89 to 10.03 mg kg(-1) with a median concentration of 3.43 mg kg(-1). Among the phthalates, DEHP was dominant and detected in all 23 soils. DEP and DBP were also in abundance, and DMP was rarely detected. Similar contamination patterns were observed in all 23 soils. A distinct feature of phthalate pollution in China was that the average concentration in northern China was higher than that in southern China. In addition, a close relationship was observed between the concentration of phthalates in soils and the consumption of agricultural film. The correlation showed that the application of agriculture film might be a significant pollution source of phthalates in arable soils of China. The potential risk of phthalates in soils was assessed on the basis of current guide values and limits.

Agriculture↗

PVC removal from mixed plastics by triboelectrostatic separation.

Ever increasing oil price and the constant growth in generation of waste plastics stimulate a research on material separation for recycling of waste plastics. At present, most waste plastics cause serious environmental problems due to the disposal by reclamation and incineration. Particularly, polyvinyl chloride (PVC) materials among waste plastics generates hazardous HCl gas, dioxins containing Cl, and so on, which lead to air pollution and shorten the life of incinerator, and it makes difficultly recycling of other plastics. Therefore, we designed a bench scale triboelectrostatic separator for PVC removal from mixed plastics (polyvinyl chloride/polyethylene terephthalate), and then carried out material separation tests. In triboelectrostatic separation, PVC and PET particles are charged negatively and positively, respectively, due to the difference of the work function of plastics in tribo charger of the fluidized-bed, and are separated by means of splitter through an opposite electric field. In this study, the charge efficiency of PVC and PET was strongly dependent on the tribo charger material (polypropylene), relative humidity (below 30%), air velocity (over 10 m/s), and mixture ratio (PET:PVC=1:1). At the optimum conditions (electrode potential of 20 kV and splitter position of -2 cm), PVC rejection and PET recovery in PET products were 99.60 and 98.10%, respectively, and the reproducibility of optimal test was very good (+/-1%). In addition, as a change of splitter position, we developed the technique to recover high purity PET (over 99.99%) although PET recovery decreases by degrees.

Air Movements↗

[Air pollution in the vicinity of streets].

Air samples were collected in plastic bags simultaneously at various measuring points in the close range of streets. When examining the various bag materials, Teflon bags showed the smallest deviations in direct analyses and in analyses of up to two hours after the drawing of samples. The following methods were used for the analysis of the air samples collected in the bags: coulometry for CO and SO2, chemiluminescence for NO/NO2, chromotrophic acid for CH2O and flame ionization for hydrocarbons. The various components were measured close to a highway and near streets in residential and business areas. The simultaneously drawn samples showed a marked dependence on traffic frequency, type of built-up area along the streets as well as meteorological conditions. An opinion survey among adjacent residents on annoyance caused by air pollution and noise resulted in distinct differences between the sections with different traffic intensity.

Air Pollutants↗

[Occupational contact of women with methylmethacrylate and the negative tendency in the process of child-bearing].

The study of women exposed to methyl methacrylate (MMA) in the workplace revealed the increased incidence of spontaneous abortions (SA). When women contacted with MMA at the MAC levels, the incidence of SA did not exceed the control levels, but the newborns were recorded to have congenital malformations, cases of hypoxia, signs of prematurity, hypotrophy, which necessitates to make stricter specifications for MAC in the workplace air and/or to lead women of childbearing age from the enterprises manufacturing MMA- and its based acrylic plastic.

Air Pollutants, Occupational↗

Emission of PCDD/F, PCB, and HCB from combustion of firewood and pellets in residential stoves and boilers.

To assess potential emissions of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and hexachlorobenzene (HCB) from residential combustion of biofuels, experiments were performed in which various types of pellets and firewood were combusted in four types of stoves and boilers, with both full and reduced rates of air supply. Intermittent combustion of wood pellets resulted in emissions of 11 ng-(WHO-TEQ)/kg combusted fuel (dry weight). A modern, environmentally certified boiler yielded somewhat lower emissions of PCCD/F and PCB than a wood stove. Both gave <0.1 ng(WHO-TEQ)/m3n (1.3-6.5 ng(WHO-TEQ)/kg) and considerably lower emissions than an old boiler (7.0-13 ng(WHO-TEQ)/kg). No positive effect on emissions could be observed in full air combustion (simulating the use of a heat storage tank) compared to combustion with reduced air. Two of the wood combustion experiments included paper and plastic waste fuels. Chlorine-containing plastic waste gave rise to high emissions: ca. 310 ng(WHO-TEQ)/ kg over the whole combustion cycle. The homologue profiles of PCDD/Fs show characteristic differences between ashes and flue gas from combustions with different levels of air supply. These differences do not, however, seem to have any correlation to the relative amount of toxic congeners.

Air Pollutants↗

Diethylhexylphthalate as an environmental contaminant--a review.

Di(2-ethylhexyl)phthalate (DEHP) is a priority pollutant in several countries; annual production amounts to 3-4 million tonnes. Approximately 95% is used as a plasticizer in polyvinylchloride (PVC). DEHP is emitted to the environment during the production of plastics and plastic products, during their use and after disposal. In the environment, physico-chemical degradation of DEHP is practically non-existent. Biodegradation occurs readily under aerobic conditions (t1/2 = 2-4 weeks), but not under anaerobic conditions. The acute toxicity of DEHP to mammals is low. Many subchronic and chronic effects have, however, been identified. The most important of these are: influence on the liver and energy metabolism, teratogenicity, adverse effects on male reproductive organs, carcinogenicity and influence on the immune system. On the basis of figures concerning human exposure, most of these effects are not likely to occur. With respect to carcinogenicity the situation is uncertain, especially for some risk groups. The ecotoxicology of DEHP is especially relevant for aquatic communities where data are contradictory: several authors have found adverse effects on Daphnia and fish species after exposure to the present environmental concentrations; others, however, produced less alarming results. Emissions of DEHP can be reduced by the biological treatment of wastewater and waste gas, the use of alternative plasticizers in PVC or the substitution of other plastics for PVC.

Abnormalities, Drug-Induced↗

Toxicology and occupational hazards of new materials and processes in metal surface treatment, powder metallurgy, technical ceramics, and fiber-reinforced plastics.

Many new materials and processes are about to find their way from the research laboratory into industry. The present paper describes some of these processes and provides an overview of possible occupational hazards and a list of chemicals used or produced in the processes. The technological areas that are considered are metal surface treatment (ion implantation, physical and chemical vapor deposition, plasma spraying), powder metallurgy, advanced technical ceramics, and fiber-reinforced plastics.

Air Pollutants, Occupational↗

Inhibition of coral fertilisation and larval metamorphosis by tributyltin and copper.

Fertilisation and larval metamorphosis of reef-building corals are important life history events leading to recruitment of juvenile corals to reef populations. Little is known of the sensitivity of these early life phases to pollution, or their relative susceptibility to certain toxicants compared with established coral colonies. Inhibition of fertilisation and larval metamorphosis of the coral Acropora millepora (Ehrenberg, 1834) was assessed in response to solutions of the antifoulants tributyltin (TBT) and copper (Cu) using laboratory-based bioassays. Nominal concentrations that inhibited 50% fertilisation and metamorphosis (IC50) were calculated from 4 h fertilisation and 24 h metamorphosis assays and were based on introduced dose. Cu was most potent towards fertilisation with an IC50 of 17.4 micrograms/l. TBT however, proved more toxic to larval metamorphosis having an IC50 of 2.0 micrograms/l. Inert surfaces coated with either Cu- or TBT-based antifouling paint also inhibited fertilisation and metamorphosis. The degree of inhibition was correlated with surface area of the paint coating. These results indicate fertilisation and metamorphosis of coral can be sensitive to active components of antifouling paints.

Animals↗

[Air pollution due to the burning of thermoplastics II (author's transl)].

Following on from the first publication, (12) concerning the burning of plastics, another 13 chemical pure polymers were burnt in an electric oven to determine the level of solid and gaseous air pollution caused by their stackgases. All 13 polymers are highly combustible but require different burning temperatures (300-900 degrees C) in order to be burnt completely (i.e. without ashrest). With the exception of PMMA and PTFE, all plastics leave a very heavy tar- and soot deposit after burning. At the other end of the scale, burning at low temperature (300 degrees C) gives rise to high concentrations of alipathic aldehyds. The pH of the exhaust-gases, dissolved in water, is neutral to strong acid (PTFE), and will cause a severe corrosion. The nitrogen-containing polymers pollute by forming cyanides, nitrogenoxides and ammonia. PTFE gives off high concentrations of fluorid into the air. PMMA decomposes in its monomer methylmethacrylate and forms large amounts of aliphatic aldehyds. ABS and SBR cause a styrene pollution.

Air Pollutants↗