[The influence of the greenhouse effect on vegetation--results of studies in England]

Studies on the effects of an increased concentration of carbon dioxide on terrestrial ecosystems have produced results on plant growth in general and on growth of forests in particular. Deciduous trees and conifers react differently to increased atmospheric CO2. In most instances, an increased growth rate can be expected. Higher CO2 concentrations can thus compensate for or alleviate other environmental stresses. Economically important species (e.g. cotton) exhibit growth retardation in the presence of increased CO2 concentrations. Raised temperatures stimulate not only growth of trees but also of typical weeds. A few scenarios of expected changes in future vegetations following a global raise in temperature are depicted.

Public exposure to environmental tobacco smoke

Airborne particulate matter has been collected by personal samplers in public indoor areas and travel situations with environmental tobacco smoke pollution. Following extraction, the samples were assayed for mutagenicity in the presence of S9 with a sensitive microsuspension test using Salmonella TA98. The mutagenic responses of indoor air from public areas were much higher than those of ambient outdoor air. Depending on the circumstances, the mutagenic response varied in trains and airplanes but the results show that physical separation of non-smoking sections from smoking sections is necessary in order to achieve genuine non-smoking areas. Chemical fractionation and mutagenicity assay of the basic fraction show that Salmonella mutagenicity of airborne particulate matter might be used as a tobacco smoke-specific indicator, as the basic fraction of environmental tobacco smoke contains a large part of the mutagenic activity whereas this is not the case for outdoor ambient airborne particulate matter.

Effects of SO2 exposure on allergic sensitization in the guinea pig

The effect of sulfur dioxide (SO2) exposure on local bronchial sensitization to inhaled antigen was studied in the guinea pig. Exposure to SO2 (0.1 to 16.6 ppm) was performed in a 20 L exposure chamber for 8 hours on 5 consecutive days, while temperature, moisture, and concentration of SO2 were monitored and kept constant. SO2 concentrations were measured hourly by Schiff's reaction. On the last 3 days, SO2 exposure was followed by inhalation of nebulized ovalbumin (OA) for 45 minutes. One week later, specific bronchial provocation with inhaled OA (0.1%) followed by plethysmographic measurements of airway obstruction were performed every 2 days during a 2-week period. Specific antibodies against OA were measured in serum and bronchoalveolar fluid by a direct enzyme immunoassay. The SO2-exposed group (N = 17) demonstrated 67% to 100% positive bronchial reactions to inhaled OA, depending on the concentration of SO2, whereas the control group without previous SO2 exposure (N = 14) demonstrated bronchial reactions in only one animal (7%: p less than 0.05). The degree of bronchial obstruction was significantly higher in the exposed group, compared to the control group, for all SO2 concentrations (p less than 0.05). OA-specific antibodies in serum and bronchoalveolar fluid increased in SO2-exposed groups significantly, compared to the control group (p less than 0.05). It is concluded from these results that exposure to SO2 in low and medium concentrations can facilitate local allergic sensitization in the guinea pig.

Mutagenic and clastogenic activity of direct-acting components from air pollutants of the Silesian industrial region

Sequential elution solvent chromatography (SESC) developed by Farcasiu for characterization of coal liquids was used for the fractionation of benzene extracts of airborne particulate pollutants. Mutagenic and clastogenic activity of SESC fractions was determined by the Salmonella/microsome test and the assay for V79 cell chromosomal aberrations (CAs), respectively. Five out of 8 obtained fractions showed differentiated, direct and indirect mutagenic activity. Selected 'direct' fractions, examined by the rodent cell chromosome aberration test, also gave a clastogenic response that increased with prolonged treatment time. The SESC system combined with 2 biological assays, the Ames test and the CAs test, seems to be a useful method for examination of genotoxic components of environmental pollutants.

Prenatal induction of benzo(a)pyrene hydroxylases in mice

1. Benzo(a)pyrene hydroxylase (BPH) activity was measured in homogenates of fetal liver (day 18) or of whole-embryos of mice on day 9, 10 or 12 of gestation after maternal pretreatment with B(a)P on 3 consecutive days. A 3H-liberation assay with 3H-B(a)P labelled either generally or at the 6-position was used. The values obtained with the embryonic/fetal tissues were compared with those found in maternal liver. 2. Three oral doses of 17.5 mg B(a)P/kg body wt were found to just significantly induce BPH in maternal liver. An induction was observed after pretreatment with 24 mg B(a)P/kg body wt in 9-, 10- or 12-day-old whole-embryos, but the Vmax reached was only 10-20% (1% on day 9) of that of adult non-induced liver. The Km (6-hydroxylation) for all tissues tested were in the same range (600-900 nM). The induction was demonstrable in embryos at tissue levels about one order of magnitude lower than those required for induction in maternal liver. 3. Treatment with 25 mg B(a)P/kg body wt on 3 consecutive days was required to induce BPH in fetal liver on day 18 of gestation. The required B(a)P tissue concentrations were about one half of those necessary for induction in maternal liver. 4. Among a variety of other polycyclic hydrocarbons only chrysene showed an inducing potency similar to that of B(a)P in adult and fetal liver. For all compounds tested there was no correlation found in the inducing potency between adult and fetal liver (e.g. coronene).(ABSTRACT TRUNCATED AT 250 WORDS)

Induction of rat hepatic cytochromes P-450 by environmental nitropolycyclic aromatic hydrocarbons

Nitrated polycyclic aromatic hydrocarbons (PAHs) are environmental contaminants that result from various incomplete combustion processes. We have examined the activity of hepatic microsomal enzymes in rats pretreated with a series of environmentally occurring nitrated PAHs including: 1- and 4-nitropyrene, 1,3-, 1,6- and 1,8-dinitropyrene, 6-nitrochrysene, 7-nitrobenz[a]anthracene, 3-nitrofluoranthene, and 1-, 3-, and 6-nitrobenzo[a]pyrene. None of the compounds increased the cytochrome P-450 content more than 2-fold. 1,8-Dinitropyrene, 6-nitrochrysene, and 1- and 3-nitrobenzo[a]pyrene significantly increased arylhydrocarbon hydroxylase activity 2- to 8-fold higher than solvent-treated controls. The induction of 7-ethoxycoumarin O-deethylase activity paralleled that found with arylhydrocarbon hydroxylase. The maximum induction of aminopyrine N-demethylase was only 1.5-fold, and none of the nitrated PAHs caused significant increases in epoxide hydrase or NADPH-cytochrome c reductase. 1-Nitropyrene reductase activity was induced by each of the compounds with the exception of 6-nitrobenzo[a]pyrene. The greatest increase was caused by 1-nitrobenzo[a]pyrene followed by 1,3-dinitropyrene, 3-nitrobenzo[a]pyrene and 6-nitrochrysene. These data suggest that nitrated PAHs may potentiate the effects of subsequent exposures to various chemical carcinogens.

Inhibition of lymphocyte blastogenesis by serum leachates of fly ash

Samples of 8 ashes were leached with canine serum for 24 h to remove metal ions from the particle surfaces. The particles were removed by filtration, and the concentrations of 11 metal ions in the serum leachates were determined by atomic absorption spectrophotometry. The leachate samples were evaluated using the canine whole-blood lymphocyte stimulation test (WB/LST). The serum extracts of oil-related ashes were highly inhibitory, while lower biological activity was observed for the extracts of coal ashes. The observed inhibition in the WB/LST was correlated with the concentration of each metal ion using Kendall's rank correlation test. The highest correlations were observed for Mn and V. The results are compared with previous WB/LST studies on pure metal salts.

Pilot survey of urinary porphyrins from persons transiently exposed to a PCB transformer fire

In rats and humans chronically exposed to large amounts of PCB (polychlorinated biphenyls) and PCDF (polychlorinated dibenzofurans), the urinary excretion of uroporphyrin and coproporphyrin are altered. However, porphyrin excretion in humans after acute transient low level exposure has not been evaluated. Following such an exposure in which bystanders and firefighters were in contact with smoke from a PCB transformer fire, we surveyed 90 self-referred individuals by questionnaire and by determining single 24 hour urinary excretion of uroporphyrin and coproporphyrin 2-4 weeks after the fire. Questionnaire variables that assessed exposure were not associated with the magnitude of either uroporphyrin or coproporphyrin excretion. Uroporphyrin excretion was slightly elevated in nine subjects (range 66-106 micrograms/24 hours, normal less than 60), which is much less than in clinical cases of porphyria cutanea tarda. Uroporphyrin excretion was inversely correlated with coproporphyrin excretion (r = -0.3844, p = 0.0002). For 5 subjects (3 with elevated initial uroporphyrin excretion) retested at 3-4 weeks after the fire, all 5 showed increases in uroporphyrin and decreases in coproporphyrin excretion when compared to initial determinations. These two reciprocal relationships would be the expected result from inhibition of uroporphyrinogen decarboxylase, a known experimental effect of PCB and PCDF in mice. Overall, urinary porphyrin excretions were not altered or sensitive measures of exposure.

Balbc/3T3 cell transformation response to extracts of organic air samples as seen by their survival in aggregate form

Extracts of organic matter from samples of airborne particulate matter have been shown to possess components capable of transforming mammalian cells. This study was done to determine if Balbc/3T3 cells exposed to extracts of air samples could, unlike their normal counterparts, in the absence of a surface for attachment, divide on agar to form aggregates, and if these cells would demonstrate a dose-response phenomenon. Untreated and solvent treated control cells failed to form large aggregates and showed a decline in viable cell number over a 6-day period. Cells treated with either cyclohexane or acetone extracts of airborne particulate matter showed a dose-response increase in cell number along with the formation of progressively larger aggregates, findings similar to those seen with the positive, benzo[a]pyrene (BaP), control. Furthermore, these findings are in direct agreement with those in the simultaneously performed standard cell transformation assay which required 21 days to perform. Results show that survival in aggregate form is a rapid in vitro test system capable of detecting potentially carcinogenic activity in complex environmental mixtures.

Respiratory effects of photochemical oxidant air pollution in exercising adolescents

Healthy volunteers 12 to 15 yr of age (46 boys, 13 girls) were exposed to purified air and to smoggy Los Angeles ambient air on different occasions. The studies were performed in random order approximately 2 wk apart. They included 1 h of continuous bicycle exercise (mean ventilation, 32 L/min) plus brief warm-up and cool-down periods. Symptoms and forced expiratory performance were recorded preexposure in purified air, immediately postexposure, and after 1 h recovery in purified air. Mean exposure temperature was 32 degrees C, and mean relative humidity was 45%. In ambient exposure, pollutant concentrations averaged 0.144 ppm for ozone and 153 micrograms/m3 for total suspended particulates. Group mean FEV1 decreased during ambient exposure (p less than 0.01) and only partially recovered during the following 1 h. Unlike adults studied previously, this subject group reported no significant increase in respiratory symptoms accompanying changes in FEV1. Adolescents may be less aware of early respiratory irritation by oxidants and thus more at risk from ambient exposures than are adults.

The effects of aerosols of carbamylcholine, serotonin and propranolol on the ventilatory response to CO2 in guinea pigs and comparison with the effects of histamine and sulfuric acid

A new method is introduced to recognize the acute pulmonary effect of airborne contaminants in guinea pigs. The method avoids anaesthesia and invasive techniques and requires minimal restraint of the animal. To recognize the acute pulmonary effect, the inspiratory volume of the animal was increased by continuous inhalation of a mixture containing 10% CO2 in 18% O2 and 72% N2. Once a plateau increase in inspiratory volume was reached, the aerosol to be studied was added to this mixture and its effect in reducing inspiratory volume measured. By exposing the animals to different exposure concentrations of carbamylcholine, serotonin and propranolol aerosols, concentration-response relationships were obtained which permitted comparison of their potency. Comparisons were also made with histamine and sulfuric acid aerosols previously studied.

Alterations in macrophage functions by environmental chemicals

The establishment of infectious diseases is rarely entirely attributed to a single entity, but instead is the result of a primary stress and one or more secondary factors that interfere with homeostasis and the ability of the host to cope with the primary etiologic assault. Any environmental chemical that can suppress the normal functioning of the host's body defenses would be expected to increase the risk of the host to such diseases. Within the lung, the alveolar macrophages are the crucial elements responsible for defending the body against such airborne viable agents. The effects of inhaled gases and particulates on these defense cells are a major concern of the environmental health scientist since such chemicals have the capability of adversely affecting the integrity and functioning of these pulmonary defense cells. The objective of this report is to provide an overview that will improve our understanding of how a variety of environmental chemicals can alter the biochemical, physiological and immunological functioning of these cells.

Effect of atmospheric ammonia on pullets at point of lay

Results obtained show that pullets exposed to 200 ppm atmospheric ammonia for 17 days had a reduced feed intake and reduced growth rate when compared to controls. After the ammonia exposure period at point of lay, percent egg production was less and mortality greater for the ammonia exposed group versus the controls.

Effect of bedding changes and room ventilation rates on blood and brain ammonia levels in normal rats and rats with portacaval shunts

Normal rats and rats with portacaval shunts were exposed to low concentrations of atmospheric ammonia generated from decomposing urine and feces. The ammonia concentration in the atmosphere was varied by altering the effective ventilation rate, animal density in the enclosure, and bedding change frequency. Atmospheric ammonia concentrations in the animal holding areas varied inversely with the frequency of bedding change and the rate of air exchange. Significant differences were found between normal and shunted animals in blood ammonia and alkaline phosphatase; brain ammonia, glutamate, and glutamine; and body weight. However, these alterations were the same regardless of the atmospheric ammonia concentration; there were no differences within the control group or shunted group housed in the different conditions. The findings suggest that in the range of ammonia concentrations in this study (0 to 9 ppm), ammonia taken in through the respiratory tract is not accumulated in the body to any significant extent.

[Normal values of methemoglobinemia in a sample of Sardinian workers]

The susceptibility of hemoglobinic iron to oxidation in the ferric form by action of numerous industrial substances, suggested the use of metHbemia dosage in biological monitoring of professional exposure to such substances. In order to have useful reference values, the metHbemia of 975 male workers, from various parts of Sardinia, was measured at least 12 hours after last work shift. 95% of the examined population had metHbemia values lower than 0,86% of total Hb; such result has been compared with other normal values, found in literature and likely causes of the differences between such values have been discussed. On the basis of our results and on the examination of literature an intervention prospectus is suggested for biological monitoring of exposure to methemoglobinising substances.

Mutagenic detection of complex environmental mixtures using the Salmonella/arabinose-resistant assay system

The mutagenic sensitivity of SV50, the R-factor plasmid containing tester, of the Salmonella/arabinose-resistant assay system has been evaluated with different environmental complex mixtures, including extracts of airborne and diesel emission particles, oil-shale ash, nitrosated coal dust and water samples. The mutagenicities of all extracts were detectable with this assay. This study indicates that the arabinose-resistant assay with SV50 is useful for the detection of the mutagenic activity of environmental complex mixtures.

The respiratory health and lung function of Anglo-American children in a smelter town

Cooper smelters are large, usually isolated, sources of air pollution. Arizona has several such plants on the periphery of small communities. The smelters emit predominantly sulfur oxides and particulates, and the residents of these communities intermittently are exposed to high concentrations (24-h sulfur dioxide (SO2) = 250 to 500 micrograms/m3) of smelter smoke but little other pollution. This study compared the respiratory health of Anglo-American school children who lived in one smelter community with children living in another small community in Arizona that was free of smelter air pollution. The prevalence of cough, as determined by questionnaire, was 25.6% in the smelter town children and 14.3% in the nonsmelter town children (p less than 0.05). Pulmonary function at the study onset was equal in the two groups. Over the course of the 4 yr of study, lung function growth (measured as actual forced expiratory volume in one second (FEV1) after 4 yr of study minus predicted FEV1) was also equal in the smelter town and nonsmelter town children. These results suggest that children in smelter communities have slightly more cough when compared with children living in other communities, but no differences in initial lung function or lung function at yearly testing over the period of the study.

Synergism in the transformation of hamster embryo cells treated with formaldehyde and adenovirus

Formaldehyde is a large production volume chemical widely distributed in research laboratories, industrial workplaces, and home and personal environments. Inhalation studies with formaldehyde have documented its ability to produce squamous cell carcinomas in rats. When primary hamster embryo cells were treated by gaseous exposure to formaldehyde or by incorporation into the medium, a dose-related increase in the frequency of SA7 virus transformation was produced. The length of chemical treatment and the time interval before subsequent addition of transforming virus was critical, with two-hr treatment times as the most efficient. Treatment by gaseous exposure permitted utilization of lower treatment concentrations. Determination of formaldehyde concentrations in culture media of bioassay dishes treated by this method documented that 2.2 micrograms/ml produced significantly enhanced viral transformation. Exposure of hamster embryo cells to formaldehyde by these methods produces reproducible and quantitative genotoxic effects.

Air pollutant sulfur dioxide-induced alterations on the levels of lipids, lipid peroxidation and lipase activity in various regions of the rat brain

The exposure of rats to SO2 (10 p.p.m.) for one hour daily for 30 days caused depletion of total lipids in all brain areas. The contents of phospholipid were elevated in cerebellum and brain stem, but were depleted in cerebral hemisphere. Cholesterol levels showed an increase in various brain regions. On the other hand, gangliosides were increased in cerebellum and brain stem, but were decreased in cerebral hemisphere. Interestingly, cholesterol/phospholipid ratio was increased in different regions of the brain. Lipase activity was elevated in cerebral hemisphere. Lipid peroxidation showed marked increment in whole brain and in all the brain areas studied. The results suggest that SO2-exposure induces degradation of lipids. Interestingly, the lipid contents are affected differentially in the various parts of the brain.