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At least 1,135 records · Page 63Linked to original sources
PubMed1988

Calibration of a solid state nuclear track detector for the measurement of indoor levels of radon and its daughters.

Time-integrated measurements of environmental radiation levels are commonly carried out using solid state nuclear track detectors (SSNTD). These detectors are particularly suitable for monitoring indoor radiation, however they should be calibrated for the measurement of the levels of radon (Rn) and its daughters likely to be found in dwellings. This paper reports the results of experiments conducted to calibrate cellulose nitrate film. LR-115 type II, which is used for the measurement of Rn levels in indoor environments of dwellings in India. The detector was exposed to varying concentrations of Rn inside an exposure chamber both in Bare and in Cup with membrane modes. We obtained calibration factors of 1.05 x 10(-3) tracks cm2 day-1 per pCi m-3 (2.84 x 10(-2) tracks cm-2 day-1 per Bq m-3) and 4.8 x 10(2) tracks cm-2 day-1 per WL of Rn.

Climate↗
PubMed1989

The assessment of air and soil as contributors of some trace metals to vegetable plants. II. Translocation of atmospheric and laboratory-generated cadmium aerosols to and within vegetable plants.

Radish, spinach and lettuce were grown in the field on 109Cd-labelled soil. Efficient transfer to the plant was observed with concentration factors [Cd concn. in plant (dry wt) divided by Cd concn. in soil (dry wt)] of between 0.30 and 2.00. Soil uptake of Cd accounted for only 69-64% of Cd in the plants, the remainder arising from atmospheric deposition. By fumigating radish, lettuce and carrot with Cd aerosol in a wind tunnel and harvesting and analysis subsequent to further growth, translocation of Cd to non-exposed parts of plants was demonstrated. The percentage of deposited Cd which is translocated in the wind-tunnel-fumigated plants is small (0.6-4%), but is larger in plants grown in the field (28-36%) or in a laboratory growth cabinet (12-35%).

Aerosols↗
PubMed1989

Formaldehyde exposure at various workplaces.

The results of formaldehyde determinations in the air at various workplaces in the period 1980-1988 are presented. The airborne concentrations varied between less than 0.01 and 10.9 mg m-3 (mean 0.7 mg m-3). For ambient air monitoring, active sampling and capillary gas chromatography are reliable and sensitive methods. Formic acid excretion in urine is an unspecific and insensitive biological indicator for monitoring low-dose formaldehyde exposure.

Air Pollutants, Occupational↗
PubMed1990

The environmental half-lives and mean residence times of contaminants in dust for an urban environment: Barrow-in-Furness.

Radiocaesium contamination of dusts from external (road and school yards) and internal (house) environments within Barrow-in-Furness was found to be derived from the primary input event of Chernobyl fallout. The specific activity of radiocaesium in the dust reservoirs studied, decreased exponentially, enabling environmental half-lives to be calculated (190-370 day). The broad similarity of these half-lives indicated that secondary contamination processes, such as atmospheric deposition of resuspended dust, cause all the internal and external reservoirs to be linked into a system encompassing much of Barrow-in-Furness. Mean residence times of external dust were derived from the calculated environmental half-lives and measurements of atmospheric deposition (150-250 day). These mean residence times are dependent on local processes and are thus site specific, whilst the environmental half-lives represent an integration of all the processes operating in Barrow-in-Furness.

Accidents↗
PubMed1990

Measurements of the equilibrium factor for 222Rn daughters in dwellings in India.

As part of an ongoing project to assess the population dose from indoor radon and its daughters in India, a set of parallel measurements was made in more than 150 houses of different types to estimate indoor radon and progeny levels. Time-integrated solid state nuclear track detectors were employed for the measurement of radon concentration and potential alpha energy exposure level. From these values the equilibrium factor (F) between radon and its progeny was estimated for each house. An average F value of 0.39 was obtained.

Housing↗
PubMed1991

Trace elements in street and house dusts: sources and speciation.

The sources and speciation of trace elements in street and house dusts are reviewed. Soil is a major component of both dusts, but a number of elements are enriched in both materials. These include Pb, Zn, Cu, Cd, As, Sb, Cr, Ca, Na, Au, Cl and Br. They arise from a number of contributing and polluting sources. In the case of house dust, some elements, such as Cu, Co, As, Sb, Zn, Cd, Au, Cl, C and Pb, are produced in the house. There are a number of problems associated with the determination of the speciation of trace elements in dusts. These include the low concentrations of many of the elements, and the interpretation of the results from selective sequential extractions. The mobility and potential availability of the trace elements from dust lies in the order Cd greater than Zn, Pb greater than Mn, Cu greater Fe.

Air Pollutants↗
PubMed1992

Lead in household dust.

The lead content of 55 samples of dust collected from vacuum cleaner bags from various parts of Denmark has been determined. The concentrations found ranged from 1.5-48.9 ppm lead in the dry dust, the geometric mean being 9 ppm which is comparable to the mean concentration of lead in Danish arable soil. No correlation was found between traffic density and concentration of lead in the dusts.

Denmark↗
PubMed1983

The influence of environmental variables on amphetamine-induced activity in the preweanling rat.

The present experiments investigated how environmental stimuli influence a behavioral response to amphetamine treatment in preweanling rats. In the first experiment, 15-day-old rats received either 1 mg/kg d-amphetamine or saline and were observed in the presence of their home shavings or in a novel cage. Results showed that although familiar cues from the home bedding decreased activity of the saline treated pups, these cues did not influence the activity-enhancing effect of amphetamine. In Experiment 2, 15-day-old pups were placed in a cage with an anesthetized adult conspecific and non-directed activity, around the cage, as well as directed activity on top of the adult were recorded. Following amphetamine treatment, animals tested with a conspecific showed no increase in non-directed activity, a finding which replicates previous observations. In the present experiment, however, a significant increase was seen in the activity directed towards or on top of the anesthetized adult. These experiments reveal that familiar cues per se are not sufficient to influence amphetamine-induced activity in young rats. Activity is influenced, specifically if familiar cues are associated with a discrete object. In the presence of a familiar stimulus, non-directed activity is decreased and directed activity is enhanced. These data are discussed in terms of clinical findings which show that amphetamine acts to focus, or direct activity of the hyperactive child, and further underlines the importance of environmental variables in influencing the amphetamine response.

Aging↗
PubMed1984

Cholecystokinin accelerates the rate of habituation to a novel environment.

Cholecystokinin (CCK8), an octapeptide present in high concentrations in both gut and brain, has been proposed as a putative satiety signal in a variety of species. Exploratory and social behaviors in particular are inhibited by exogenously administered CCK8. One hypothesis for the mechanism by which CCK reduces feeding and exploration is that CCK8 is reducing arousal and attention to environmental stimuli. This possibility was tested by analyzing the rate of habituation to the novelty of objects placed in an unfamiliar arena. A video-tracking computer-assisted animal behavior monitor measured four parameters of exploratory behaviors in rats pretreated with intraperitoneal CCK8. During the first 30 minutes in the novel environment, CCK8-treated animals showed a reduced latency to cessation of exploration as compared to saline controls. In repeated five minute sessions on consecutive days, CCK8 treatment accelerated the decline in exploration over daily sessions. Pentobarbital, a known sedative, induced low levels of exploration throughout the repeated daily sessions. These data suggest that CCK8 is inducing a more rapid rate of habituation to the novelty of environmental stimuli. An accelerated rate of habituation might underlie some of the satiety-related behavioral effects of this peptide.

Animals↗
PubMed1991

Particle penetration into the automotive interior. I. Influence of vehicle speed and ventilatory mode.

Penetration of particulate aeroallergens into the interiors of two, new, similar Chrysler Corporation passenger vehicles (having no evidence of intrinsic microbial contamination) was studied on a large circular test track during periods of high pollen and spore prevalence. Impactor collections were obtained at front and rear seat points and at the track center during periods with (1) windows and vents closed and air conditioning on, (2) windows closed, vents open, and no air conditioning, and (3) air conditioner off, front windows open, and vents closed. These conditions were examined sequentially during travel at 40, 50, 60, and 80 kph. Particle recoveries within the two, new, similar Chrysler Corporation passenger vehicles did not vary with the speed of travel, either overall or with regard to each of the three ventilatory modalities. In addition, collections at front and rear seat sampling points were comparable. Highest interior aeroallergen levels were recorded with WO, and yet, these levels averaged only half the concurrent outside concentrations at track center. Recoveries within the cars were well below recoveries obtained outside when windows were closed (both VO and AC modes). These findings suggest window ventilation as an overriding factor determining particle ingress into moving vehicles. Efforts to delineate additional determinants of exposure by direct sampling are feasible and would appear essential in formulating realistic strategies of avoidance.

Aerosols↗
PubMed1985

Mutagenic/carcinogenic agents in indoor pollutants; the dinitropyrenes generated by kerosene heaters and fuel gas and liquefied petroleum gas burners.

Incomplete combustion of kerosene heater, and fuel gas and liquefied petroleum gas-burner emissions produces indoor pollutants that may be carcinogenic. The incomplete-combustion products from each type of appliance were therefore collected by adsorption on about 3 g of XAD-2 resin, and were extracted with benzene-methanol as a solvent for determination and identification of mutagens in the Salmonella-microsome test system. Benzene-methanol extracts of the particulates generated by a heater and two burners showed extreme mutagenicity for strains TA97 and TA98 without S9 mix. Based on the results of analysis, a combination of high performance liquid chromatography (h.p.l.c.) and gas chromatography (GC), about 40-80% of the direct-acting mutagenicity in each crude extract showed the same h.p.l.c. and GC retention times as dinitropyrenes (1,3-, 1,6- and 1,8-isomers), and 1-nitropyrene. Moreover, other nitroarenes, 2-nitrofluorene, 1,5- and 1,8-dinitronaphthalene, and 4,4'-dinitrobiphenyl, were detectable in almost all samples, but their contribution to the mutagenicity of each extract was very low. Kerosene heaters were found to generate small amounts (0.2 ng/h) of dinitropyrenes, which are potential mutagens/carcinogens, only after 1 h of operation.

Air Pollutants↗
PubMed1986

Sister-chromatid exchanges in lymphocytes of anatomy students exposed to formaldehyde-embalming solution.

Sister-chromatid exchanges measured in the peripheral lymphocytes of 8 non-smoking persons after exposure to formaldehyde-embalming solution during a 10-week anatomy class showed a small (P = 0.02) average increase when compared with samples obtained from the same individuals immediately before exposure began. Breathing-zone air samples collected during dissection procedures showed a mean concentration of 1.2 ppm (1.5 mg/m3) formaldehyde.

Adult↗
PubMedDate not supplied

Effects of conditioned fear and environmental novelty on plasma beta-endorphin in the rat.

The levels of rat plasma beta-endorphin-like immunoreactivity following a 30 min exposure to (1) an unfamiliar operant chamber, (2) an unfamiliar operant chamber providing a VI-5 second schedule of 3 mA, 1 sec footshocks, or (3) a familiar chamber providing no shocks, but previously paired with unavoidable shocks were compared to control values from animals left undisturbed in their familiar home cages. The shocked group showed ten-fold elevations of beta-endorphin-like immunoreactivity compared to the undisturbed control animals, while conditioned rats showed a smaller two-fold elevation when re-exposed to a chamber in which they had previously been shocked. Two of five rats exposed merely to an unfamiliar chamber showed elevations, but there was no statistically reliable group effect. Such procedures may be useful for controlled and parametric studies of the mobilization of pituitary or brain pools of beta-endorphin under conditions involving merely anticipation of pain rather than the actual activation of ascending nervous pain pathways.

Animals↗
PubMed1982

Urine calcium concentrations in bullfrog tadpoles kept in tap water or high calcium environment, with special reference to ultimobranchialectomy.

1. Urine calcium concentrations were determined in intact and ultimobranchialectomized bullfrog tadpoles kept in tap water (Ca: 8.5 and 19.7 mg/100 ml), urine calcium levels did not show significant increases. 3. In ultimobranchialectomized tadpoles, hypercalciuria concomitant with the rise in serum calcium levels in recognized under both conditions of high calcium water and tap water. 4. It was suggested that in bullfrog tadpoles ultimobranchial glands do not exert effective influences on the renal handling of calcium.

Acclimatization↗
PubMed1986

Ammonia levels in the whelping nests of farmed raccoon dogs and polecats.

Ammonia concentrations were measured in the nests of farmed raccoon dogs (Nyctereutes-procyonoides Gray, 1834) and polecats (Mustela putorius) at weaning time. Ammonia levels in the nests of raccoon dogs and polecats varied from 1 to 43 ppm and from 0 to 5 ppm, respectively. In the raccoon dog, with increasing litter size, the ammonia concentrations tended to increase exponentially. In the polecat, no marked relationship between litter size and ammonia levels were found. The results show that no special adaptations are required in farm life because even the highest ammonia concentrations measured were below the harmful level.

Ammonia↗