Responses in the respiratory tract of rats following exposure to sulphuric acid aerosols for 5 or 28 days

Sulphuric acid mists have been classified by the International Agency for Research on Cancer as being carcinogenic to humans based on epidemiological findings of respiratory tract tumours. To determine if early changes in the respiratory tract following exposure to sulphuric acid (H(2)SO(4)) aerosols are consistent with the possible development of tumours after extended periods of exposure, groups of female rats were exposed to respirable aerosols of H(2)SO(4) at target concentrations of 0, 0.2, 1.0 or 5.0 mg m(-3) for 6 h per day for either 5 days or for 5 days a week over a 28-day period. Additional groups exposed to 0 or 5.0 mg m(-3) over the 28-day period were retained after exposure for 4 or 8 weeks to assess recovery. Histopathological examinations and quantitative cell proliferation measurements were conducted on the nasal passages, larynx and lung. Achieved concentrations were 0.3, 1.38 and 5.52 mg m(-3) H(2)SO(4). Histological and cell proliferative changes were confined to the larynx and no effects were seen in the nasal passages or lungs. At the two highest concentrations, squamous metaplasia accompanied by significant cell proliferation was apparent after 5 and 28 days of exposure and there was a reduction in the severity of the pathological changes following the recovery periods. No effects were seen at 0.3 mg m(-3) after 5 days of exposure and only minimal metaplastic change was seen after 28 days in a few animals and was not accompanied by cell proliferation. The toxicological relevance of these findings is discussed.

Analysis of individual versus group behavior of zebrafish: a model using pH sublethal effects

An image analysis biomonitoring system was used to evaluate sublethal effects of pH on the mean swimming velocity of zebrafish. Responses to stress were tested comparing individual and group responses. Group analysis indicated no effect for all acid pH and for pH 9.0-9.5. Individual analysis indicated behavioral differences for most acid pH and higher than 9.5. Sensitivity to sublethal pH was best assessed when using individual analysis. Zebrafish decreased hyperactivity and increased hypoactivity with more acid or alkaline pH. Individual approach allowed to determine hyperactivity or hypoactivity and the species' thresholds of exposure, which is critical for the management of impairments.

Sulfuric acid induces airway hyperresponsiveness to substance P in the guinea pig

We investigated whether sulfuric acid inhalation would cause hyperresponsiveness to substance P. Guinea pigs became dyspneic during a 1 h sulfuric acid exposure, but recovered by 24 h when they were challenged with substance P or histamine aerosols. Eight minutes after the start of challenge, animals were killed and excised lung gas volumes measured. Sulfuric acid slightly increased histamine responsiveness compared to controls. However, sulfuric acid caused a much more pronounced leftward shift in the dose response to substance P. Coadministration of the neutral endopeptidase (NEP) inhibitor, thiorphan, did not reduce sulfuric acid-related hyperresponsiveness to substance P. By 72 h, sensitization to substance P was absent. Histological evaluation of sulfuric acid-treated lungs revealed mild alveolitis at 24 h, but not at 72 h. We conclude that sulfuric acid produces a marked sensitization to substance P. Inactivation of NEP does not appear to account for this effect.

Sulfuric acid aerosol induces changes in alveolar surface tension in the guinea pig but not in the rat

The purpose of this study was to investigate the effects of an acid aerosol, at high concentration, on the surface properties of the extracellular fluid lining the airways and alveolae. Guinea pigs and rats were exposed to 43 mg/m3 and 94 mg/m3 of sulfuric acid aerosol mass median aerodynamic diameter (MMAD) 0.9 micron or water aerosol (control), respectively, for 4 hours in an exposure chamber. Surfactant material was extracted from bronchoalveolar lavage fluid (BAL) by centrifugation, and phospholipid, protein, and cell concentrations measured. The extract was reconstituted to 300 micrograms/mL of phospholipid, and its surface properties assessed with a captive bubble surfactometer. The minimum surface tension for the acid-exposed guinea pig BAL was 12.1 +/- 8.48 (mean +/- SD) mN/m, which was significantly higher than the control group, 2.0 +/- 0.43 (mean +/- SD) or the acid-exposed rats, 1.29 +/- 0.11 (mean +/- SD). The change in film area obtained by compressing the film from equilibrium surface tension (25 mN/m) to its minimum value (gamma min) was 62.9 +/- 13.83 (mean +/- SD)% for acid-exposed guinea pigs, compared to 16.3 +/- 5.77 (mean +/- SD)% for the control guinea pigs. The most sensitive index of surfactant inhibition was found to be the maximum film compressibility (Cmax) of the compression isotherm. This index was 119 times greater for the acid-exposed guinea pigs compared to control animals. These abnormalities were associated with an elevation of total protein (0.95 +/- 0.33 [mean +/- SD] mg/mL compared to 0.13 +/- 0.03 [mean +/- SD] mg/mL in controls) and polymorphonuclear leucocytes in the BAL. There was no change in total phospholipids. By contrast BAL retrieved from rats exposed to approximately twice the concentration of acid aerosol showed no cellular nor biochemical abnormalities and its surface tension properties were normal. We conclude that the abnormalities of surfactant activity in the acid-exposed guinea pigs result from the cellular and humoral responses of acute lung injury rather than a direct effect of acid.

Individual and combined effects of fluoranthene, phenanthrene, mannitol and sulfuric acid on marigold (Calendula officinalis)

A study was conducted to characterize marigold stress response to polycyclic aromatic hydrocarbons (PAHs) (oxidative stress inducers) with and without sulfuric acid (S.Acid; pH 3) (acid-stress inducer), and to evaluate reactive oxygen species (ROS) scavenging activity of mannitol (Mann). Marigold (Calendula officinalis) seedlings were grown in a greenhouse and fumigated with fluoranthene (FLU), phenanthrene (PHE), Mann, and S.Acid individually and in various combinations for 40 days. Various physiological and biochemical parameters among others were analyzed using standard methods. The results revealed that fumigation of FLU induced oxidative stress to the plants via ROS generation leading to negative effects on photosynthesis at near saturating irradiance (A_max), stomatal conductance (G_s), internal carbon dioxide concentration (C_i), leaf water relations and chlorophyll pigments. Significant per cent inhibition of A_max (54%), G_s (86%) and C_i (32%), as well as per cent reductions in chlorophyll a (Chl.a) (33%), Chl.b (34%), and total chlorophyll (Tot. Chl) (48%) contents were recorded in FLU fumigated treatment in comparison to control. Combination of Mann with FLU scavenged the generated ROS and substantially lowered the oxidative stress on the plants hence all the measured parameters were not significantly different from control. PHE fumigation had varied effects on marigold plants and was not as deleterious as FLU. Combined fumigation of S.Acid with both the PAHs had significant negative effect on leaf water relations, and positive effect on fresh and turgid weight of the plants but had no effect on the other measured parameters. The lowest proline contents and highest catalase and ascorbate peroxidase activities in FLU fumigated plants further confirmed that oxidative stress was imposed via the generation of ROS. From the results, it is evident that Mann could be an efficient scavenger of ROS-generated by FLU in the marigold plants. We recommend Mann to be widely used for the protection of higher plants from FLU-generated stress in the urban areas.

Mutagenesis of anaerobic cultures of Salmonella typhimurium by nitrosoguanidine, diethyl sulfate and 9-aminoacridine

Despite a previous report to the contrary, anaerobic cultures of Salmonella typhimurium strain LT2 hisG46 are revertible (although to a slightly reduced extent) by both N-methyl-N'-nitro-N-nitrosoguanidine and diethyl sulfate, while anaerobic cultures of a strain carrying the frameshift hisC3076 marker are fully revertible by 9-aminoacridine.

Erosion of the teeth due to sulphuric acid in the battery industry

This paper examines the effects of sulphuric acid on the teeth of workers in the storage battery industry. The manufacturing processes are described. A statistical analysis is given of the findings in a group of workers exposed to acid and an unexposed control group. It is found that only men exposed to acid mist display erosion of the incisor teeth and that the degree of erosion is classifiable into four groups. The clinical picture of each group is described. There is progressive destruction of the tooth crown from direct impingement of acid droplets. Advanced cases show almost complete loss of crown. Erosion ceases when lip level is reached. The erosion process is painless. The factors influencing the degree of erosion are investigated. These seem to be: length of exposure, lip level, and concentration of acid in the air. The differential diagnosis from other causes of tooth destruction is given. The findings of other workers in the field are compared. Several methods of prevention are discussed.

Metabolic response of vetiver grass (Chrysopogon zizanioides) to acid mine drainage

Acid mine drainage (AMD) is a sulfuric discharge containing metals and particulates that can spread to nearby water sources, imposing toxicity and physical stress to living things. We have shown that vetiver grass (Chrysopogon zizanioides) is capable of tolerating and treating AMD-impacted water from the abandoned Tab-Simco mining site from southern Illinois, though little is known about its tolerance mechanisms. We conducted metabolomic analyses of vetiver shoots and roots after relatively short- and long-term periods of exposure to Tab-Simco AMD. The metabolic shift of vetiver shoots was dramatic with longer-term AMD exposure, including upregulation of amino acid and glutathione metabolism, cellular respiration and photosynthesis pathways, with downregulation of phosphorylated metabolites. Meanwhile, the roots demonstrated drastic downregulation of phospholipids and phosphorylated metabolites, cellular respiration, glyoxylate metabolism, and amino acid metabolism. Vetiver accumulated ornithine and oxaloacetate in the shoots, which could function for nitrogen storage and various intracellular functions, respectively. Organic acids and glutathione were secreted from the roots for rhizospheric metal-chelation, whereas phosphorylated metabolites were recycled for phosphorus. These findings reveal AMD-induced metabolic shifts in vetiver grass, which are seemingly unique in comparison to independent abiotic stresses reported previously.

Photosynthetic and growth responses of Schima superba seedlings to sulfuric and nitric acid depositions

A continuing rise in acid deposition can cause forest degradation. In China, acid deposition has converted gradually from sulfuric acid deposition (SAD) to nitric acid deposition (NAD). However, the differing responses of photosynthesis and growth to depositions of sulfuric vs. nitric acid have not been well studied. In this study, 1-year-old seedlings of Schima superba, a dominant species in subtropical forests, were treated with two types of acid deposition SO4 (2-)/NO3 (-) ratios (8:1 and 0.7:1) with two applications (foliar spraying and soil drenching) at two pH levels (pH 3.5 and pH 2.5) over a period of 18 months. The results showed that the intensity, acid deposition type, and spraying method had significant effects on the physiological characteristics and growth performance of seedlings. Acid deposition at pH 2.5 via foliar application reduced photosynthesis and growth of S. superba, especially in the first year. Unlike SAD, NAD with high acidity potentially alleviated the negative effects of acidity on physiological properties and growth, probably due to a fertilization effect that improved foliar nitrogen and chlorophyll contents. Our results suggest that trees were damaged mainly by direct acid stress in the short term, whereas in the long term, soil acidification was also likely to be a major risk to forest ecosystems. Our data suggest that the shift in acid deposition type may complicate the ongoing challenge of anthropogenic acid deposition to ecosystem stability.

Pulmonary function and bronchial reactivity in human subjects with exposure to ozone and respirable sulfuric acid aerosol

The effect of 0.3 ppm ozone with a subsequent exposure to 100 micrograms/m3 sulfuric acid aerosol was studied in 12 nonsmoking subjects to determine if preexposure to ozone would sensitize them to sulfuric acid aerosol. Pulmonary function and bronchial reactivity measurements were made after single and sequential exposures to these pollutants. No significant changes in pulmonary function or bronchial reactivity to methacholine were observed. However, a decrease in bronchial reactivity approaching significance occurred after the 4-h exposure to 100 micrograms/m3, 0.13 microns sulfuric acid aerosol. We conclude that there are no readily apparent risks from sequential exposures of nonsmokers to low concentrations of ozone and sulfuric acid aerosol during light-to-moderate exercise.

Ventilatory responses in awake guinea pigs exposed to acid aerosols

This study reports experiments designed to evaluate the dose and temporal effects of an atmospheric pollutant, sulfuric acid (H2SO4) aerosol, on the dynamic components of the respiratory cycle. Ventilation was measured in a whole-body barometric plethysmograph in unanesthetized, unrestrained animals following a 4-h exposure to H2SO4 aerosol at 14.1, 20.1, or 43.3 mg/m3. Lung injury was assessed by histopathology and bronchoalveolar lavage (BAL). Aerosol exposure with H2SO4 caused marked alterations in both the magnitude and composition of the ventilatory response, which were both dose and time dependent. At the highest concentration tested, there was a significant increase in tidal volume (deltaVt) and a decrease in breathing frequency (f) immediately after exposure. Analysis of BAL fluid at this time showed increased inflammatory cells and protein in the acid exposed animals, and histology showed hyaline membranes and acute inflammatory cells in the proximal acinar region. By 24 h postexposure, f significantly increased whereas deltaVt decreased. This pattern of breathing was interspersed with short periods of apnea. The onset of rapid, shallow breathing was associated with histological evidence of diffuse pulmonary edema. By contrast, the immediate postexposure period at the lowest concentration of H2SO4 aerosol was characterized by a significant increase in f and little or no effect on deltaVt. These effects diminished with time, and at 24 h postexposure ventilatory parameters were indistinguishable from baseline values. An apparent crossover between the effects associated with the high and low exposure concentrations was seen at the intermediate exposure concentration; however, closer inspection of these findings on an animal-by-animal basis revealed two populations of animals with respiratory characteristics of either the high-exposure or low-exposure groups. The data suggest that the guinea pig exhibits complex interactions between dose and time to response that are consistent with the activation of neural reflexes. The indirect plethysmographic method provides a simple means to assess these responses in a model system that avoids the use of anesthetics, surgery, and restraint.

The pathogenesis of synergistic lung damage in mice by an environmental irritant (H2SO4) and particulate antigen

Daily inhalation by mice of an environmental irritant (H2SO4) followed by consequent respiratory immunization with a particulate antigen (sheep red blood cells, SRBC) induced severe interstitial pneumonitis. Inhalation of H2SO4 per se resulted in accumulation of i.v. injected globulin in the lungs of mice, without significant change in lung weight. In addition, when marker colloidal carbon particles were injected i.v. following H2SO4 inhalation, the carbon was rapidly trapped in the capillary wall in the lungs. Homologous anti-SRBC serum instilled into the respiratory tract followed by subsequent SRBC inhalation produced inflammation and injury similar to that generated by H2SO4 in combination with particulate antigen. It is postulated that following irritant inhalation, the permeability of alveolocapillary membranes increases, so that immune complexes formed by pre-existing circulating antibodies and inhaled antigen can initiate subsequent lung injury.

The use of Sunpatiens (Impatiens spp.) as a bioindicator of some simulated air pollutants--using an ornamental plant as bioindicator

Sunpatiens were exposed separately or combined to ozone gas (130 ppb), fluoranthene (10 microM) and sulphuric acid mists (pH 3) sprayed as simulated pollutants in chamber conditions for 21 d. The treatments negatively affected the gas (CO(2) and moisture) exchange, leaf chlorophyll fluorescence, and the leaf-quality expressed in chlorophyll value (SPAD). Fluoranthene and the acid individual negative effects on the measured eco-physiological variables were nearly the same on Sunpatiens; their effects became aggravated on combining the duo. The foliar symptom assessments of chlorosis, necrosis and stippling revealed severe damages in ozone containing treatments compared with other treatments. The presence of fluoranthene exuberate ozone negative effects on some of the plant eco-physiological status. Where mannitol (1mM) additions were contained in treatments, mitigation effects of the negative impact of pollutants resulted. These findings indicated that Sunpatiens can be used as an active bioindicator of singular and multiple pollutants in field conditions.

Effect of alcohol sulfate, linear alkylbenzene sulfonate and natural soap on the development of fertilized eggs of the mouse in vitro

Eggs from B6 x C3F1 female mice, which were fertilized in vitro with sperm from C3 x 101F1 male mice, were treated with synthetic surfactants, alcohol sulfate (AS) and linear alkylbenzene sulfonate (LAS), and natural soap for 1 h at the pronucleus stage, and then cultivated for 5 days. Eggs treated with AS or LAS at concentrations of less than 0.025% developed to the blastocyst stage as well as the untreated ones. At concentrations of AS or LAS higher than 0.03% no egg developed beyond the 1-cell stage. There appeared to be a threshold concentration between 0.025% and 0.03% of AS or LAS on the development of the mouse egg. However, natural soap had no effect on the development of the mouse egg up to 0.05%. When AS or LAS was applied to the culture medium throughout the cultivation of fertilized eggs for 5 days, there also appeared to be a threshold concentration between 0.01% and 0.025%, but not in the case of natural soap. The results provide additional support to our previous observations that AS and LAS can interrupt mouse pregnancy by killing fertilized eggs.

Effects of sulfur oxides on eicosanoids

Ultrafine metal oxides and SO2 react during coal combustion or smelting operations to form primary emissions coated with an acidic SOx layer. Ongoing work in this laboratory has examined the effects of sulfur oxides on pulmonary functions of guinea pigs. We have previously reported that 20 micrograms/m3 acidic sulfur oxide as a surface layer on ultrafine ZnO particles decreases lung volumes, decreases carbon monoxide diffusing capacity, and causes lung inflammation in guinea pigs after 4 daily 3-h exposures. It also produces bronchial hypersensitivity following a single 1-h exposure. The importance of this surface layer is demonstrated by our observation that 200 micrograms/m3 of sulfuric acid droplets of equivalent size are needed to produce the same degree of hypersensitivity. This study characterized the concentration-dependent effects of in vivo exposures to sulfur oxides on arachidonic acid metabolism in the guinea pig lung, and investigated the time course and the relation between eicosanoid composition and pulmonary functions. We focused specifically on four cyclooxygenase metabolites of arachidonic acid, that is, prostaglandins (PG) E1, F2 alpha, 6-keto prostaglandin F1 alpha, and thromboxane (Tx) B2, and two groups of sulfidopeptide leukotrienes (C4, D4, E4, and F4). Guinea pigs were exposed to ultrafine ZnO aerosol (count median diameter = 0.05 microns, sigma g = 1.80) with a layer of acidic sulfur oxide on the surface of the particles. Lung lavage was collected after exposures, and the levels of arachidonic acid metabolites were determined using radioimmunoassay (RIA). Concentration-dependent promotion of PGF2 alpha and concentration-dependent suppression of LtB4 were observed. The increased PGF2 alpha was associated with depressed vital capacity and diffusing capacity of the lungs measured in guinea pigs exposed to the same atmosphere described in a previous study. There is no causal relationship between the levels of other arachidonic acid metabolites and the pulmonary functional changes after exposures to these aerosols.

A mammalian cell variant in which 3-aminobenzamide does not potentiate the cytotoxicity of dimethyl sulphate

Variants of mouse leukaemia L1210 cells have been isolated in which cytotoxicity to dimethyl sulphate is not fully potentiated by ADP-ribosyl transferase inhibitor 3-aminobenzamide, as occurs in normal L1210 cells. These variants were selected after mutagenesis by growing the cells in dimethyl sulphate and 3-aminobenzamide. The characterisation of one of these variants is described. Variant 3 cells repair low doses of DNA damage in the presence of ADP-ribosyl transferase inhibitors. The Vmax of the ADP-ribosyl transferase enzyme in these cells is only increased 35% compared to normal wild-type L1210 cells. The basal DNA ligase I activity is increased 66% above wild-type whereas DNA ligase II activity appears to be unchanged. The most striking observation, however, is that the DNA ligase II activity is not increased after dimethyl sulphate treatment as occurs in wild-type L1210 cells. It seems that by increasing DNA ligase I levels these cells can survive DNA damage in the presence of 3-aminobenzamide. This variant (mutant) provides genetic evidence for our previously published hypothesis that (ADP-ribose)n biosynthesis is required for efficient DNA repair after DNA damage by monofunctional alkylating agents, because ADP-ribosyl transferase activity regulates DNA ligase activity. This variant is the first mammalian cell reported in which DNA ligase activity is altered, as far as we are aware. In yeast, a DNA ligase mutant has a cell division cycle (cdc) phenotype. Presumably, DNA ligase is essential for DNA synthesis, repair and recombination. The present variant provides further evidence that in mammalian cells, DNA ligase II activity is related to ADP-ribosyl transferase activity.

Cytotoxic and genotoxic effect in RTG-2 cell line exposed to selected biocides used in the disinfection of cooling towers

The cytotoxic and genotoxic effects induced by trichloroisocyanuric acid, Oxone, and sodium bromide, active principles included in formulations for cleaning and disinfection of cooling towers, were studied on RTG-2 cell line. Neutral red assay was used to determine the cellular viability. Toxicity ranking based on IC(50) values found that trichloroisocyanuric acid was the most cytotoxic biocide tested followed by Oxone, whereas sodium bromide resulted in a very low cytotoxicity. DNA damage has been evaluated on RTG-2 cultures by means of an in vitro assay based on the ability of PicoGreen fluorochrome to interact preferentially with dsDNA, and the results indicated that trichloroisocyanuric acid induced DNA strand breaks at concentrations above 1.2 mg/l, equivalent to 1/50-EC(50(48)), whereas exposures to Oxone and sodium bromide did not induce DNA damage at the maximal concentrations tested (1/10-EC(50(48))). These results confirm the suitability of this method for the screening of genotoxic effects of this type of aquatic pollutants, and we suggest their use in environmental risk assessment procedures.

Symptom base rates after chemical exposure for white, Hispanic and African-Americans

The results of a symptom checklist of three matched-pair studies (N = 460) of the following exposed groups are presented: Study 1, a primarily white community (N = 220) environmentally exposed to the pesticide metam sodium; Study 2, a Hispanic group (N = 180) who worked in a microelectronics plant and had extensive past exposure (M = 6.7 yrs) to multiple organic hydrocarbon solvents; and Study 3, an African-American group (N = 168) environmentally exposed to sulfuric acid. Each exposed group was compared to a matched (race, age +/- 3 years, gender, education +/- 2 years and number of children) unexposed reference group, resulting in 90 pairs for the white metam sodium group, 62 pairs for the Hispanic organic solvent group, and 78 pairs for the African-American sulfuric acid group. Symptom prevalence rates and relative risk ratios show very strong associations: in Study 1, the relative risk for all 33 symptoms ranged from 1.5 to 37; in Study 2, the relative risk for 31 of the symptoms ranged from 1.5 to 11.1; and in Study 3, the relative risk for 16 of the symptoms ranged from 1.5 to 6. Mann Whitney U results of each symptom indicate significantly greater symptomatology in the exposed vs. the reference groups in all three studies: in Study 1, at p < .01 for all 33 symptoms; in Study 2, at p < .01 for 31 symptoms, and p < .05 for one additional symptom; and in Study 3, at p < .01 for 24 symptoms and p < .05 for another three symptoms. These results suggest a robust symptom complex following chemical exposure regardless of specific chemical.