Characterization of controlled trials on probiotic supplementation to dairy calves: A scoping review

The objective of this scoping review was to identify, describe, and characterize the literature on probiotic supplementation in dairy calves. Eligible studies were nonrandomized, quasi-randomized and randomized controlled trials in English, Spanish, or Portuguese that evaluated the effect of probiotic supplementation on growth and health of dairy calves. The search strategies were based on a modification of the PICO (Population, Intervention, Comparator, Outcome) framework and used synonyms and words related to "dairy calves" (population), "probiotics" (intervention), and "growth and health measurements" (outcomes). No restrictions for publication year or language were applied. Searches were conducted in Biosis, CAB Abstracts, Medline, Scopus, and the Dissertations and Theses Database. In total, the search identified 4,467 records, of which 103 studies (110 controlled trials) met the inclusion criteria. The studies were published between 1980 and 2021 and originated from 28 countries. Trials were randomized (80.0%), nonrandomized (16.4%), and quasi-randomized (3.6%), ranging in sample size from 5 to 1,801 dairy calves (mode = 24; average = 64). Enrolled calves were frequently Holstein (74.5%), males (43.6%), and younger than 15 d at the beginning of probiotic supplementation (71.8%). Often, trials were conducted in research facilities (47.3%). Trials evaluated probiotics with single or multiple species of the same genus: Lactobacillus (26.4%), Saccharomyces (15.4%), Bacillus (10.0%), Enterococcus (3.6%), or multiple species of various genera (31.8%). Eight trials did not report the probiotic species used. Lactobacillus acidophilus and Enterococcus faecium were the species most supplemented to calves. The duration of probiotic supplementation ranged from 1 to 462 d (mode = 56; average = 50). In trials with a constant dose, it ranged from 4.0 × 106 to 3.7 × 1011 cfu/calf per day. Most probiotics were administered mixed solely into feed (88.5%; whole milk, milk replacer, starter, or total mixed ration) and less frequently orally as a drench or oral paste (7.9%). Most trials evaluated weight gain (88.2%) as a growth indicator and fecal consistency score (64.5%) as a health indicator. Our scoping review summarizes the breadth of controlled trials evaluating probiotic supplementation in dairy calves. Differences in intervention design (mode of probiotic administration, dose, and duration of probiotic supplementation) and outcomes evaluation (type and methods) justify future efforts toward standardized guidelines in clinical trials.

In vitro cytotoxicity testing of airborne formaldehyde collected in serum-free culture media

The purpose of this study was to identify a suitable sampling model for on-site toxicity assessment of soluble air contaminants such as formaldehyde, a well known industrial and indoor air contaminant. The in vitro cytotoxicity of formaldehyde, the selected model for soluble air contaminants, was studied using the MTS (tetrazolium salt) assay in two carcinoma cell lines, A549 epithelial lung and HepG2 hepatocarcinoma, and in skin fibroblasts. The cytotoxic effects of airborne formaldehyde were evaluated using test atmospheres in concentrations below 10 ppm (12.3 mg/m3), generated by a dynamic diffusion method and bubbled (0.3 L/min) through serum-free culture media for one or four hours. Human cells were treated with formaldehyde air samples, and cell viability was determined after four hours incubation. In parallel, the concentration of airborne formaldehyde was monitored, using the 3500 NIOSH method. Cell viability of the HepG2 cells exposed to formaldehyde air samples (8.75 ppm-4 h) was reduced to less than 50% (31.69/1.24%). The HepG2 cell lines were found to be more sensitive (IC50=103.799/23.55 mg/L) to formaldehyde than both A549 cell lines (IC50=198.369/9.54 mg/L) and skin fibroblasts (IC50=196.689/36.73 mg/L) (PB/0.01). An average of 96.8% was determined for collection efficiency of formaldehyde in serum-free culture media. The results of this study suggest that absorption of soluble air contaminants, such as formaldehyde, in serum-free culture media can be used as a suitable sampling model for on-site toxicity assessments.

Toxicity Assessment of Industrial Chemicals and Airborne Contaminants: Transition fromIn VivotoIn VitroTest Methods: A Review

Exposure to occupational and environmental contaminants is a major contributor to human health problems. Inhalation of gases, vapors, aerosols, and mixtures of these can cause a wide range of adverse health effects, ranging from simple irritation to systemic diseases. Despite significant achievements in the risk assessment of chemicals, the toxicological database, particularly for industrial chemicals, remains limited. Considering there are approximately 80,000 chemicals in commerce, and an extremely large number of chemical mixtures, in vivo testing of this large number is unachievable from both economical and practical perspectives. While in vitro methods are capable of rapidly providing toxicity information, regulatory agencies in general are still cautious about the replacement of whole-animal methods with new in vitro techniques. Although studying the toxic effects of inhaled chemicals is a complex subject, recent studies demonstrate that in vitro methods may have significant potential for assessing the toxicity of airborne contaminants. In this review, current toxicity test methods for risk evaluation of industrial chemicals and airborne contaminants are presented. To evaluate the potential applications of in vitro methods for studying respiratory toxicity, more recent models developed for toxicity testing of airborne contaminants are discussed.

Comparative in vitro cytotoxicity assessment of selected gaseous compounds in human alveolar epithelial cells

Exposure to airborne contaminants is significantly associated with human health risks, ranging from bronchial reactivity to morbidity and mortality due to acute intense or long term low level repeated exposures. However, the precise mechanisms that derive such effects are not always understood. Although inhalation studies are technologically complicated, correct hazard characterisation is essential for comparable risk assessment of inhaled materials. The aim of this study was to investigate the comparative in vitro cytotoxicity of selected gaseous contaminants in human lung cells. The cytotoxicity of nitrogen dioxide (NO(2)), sulphur dioxide (SO(2)) and ammonia (NH(3)) was investigated in A549- human pulmonary type II-like epithelial cell lines cultured on porous membranes in Snapwell inserts. A dynamic direct exposure method was established by utilizing the horizontal diffusion chamber system (Harvard Apparatus Inc, USA) for delivery of test atmospheres. Test atmospheres were generated using a dynamic direct dilution method and the concentration monitored by appropriate analytical methods. A diversified battery of in vitro assays including the MTS (tetrazolium salt; Promega), NRU (neutral red uptake; Sigma) and ATP (adenosine triphosphate; Promega) assays was implemented. Airborne IC(50) (50% inhibitory concentration) values were calculated based on the most sensitive assay for each test gas including NO(2) (IC(50)=11+/-3.54 ppm; NRU)>SO(2) (IC(50)=48+/-2.83 ppm; ATP)> and NH(3) (IC(50)=199+/-1.41 ppm; MTS). However, all in vitro assays revealed similar toxicity ranking for selected gaseous contaminants. Identical toxicity ranking was achieved using both in vitro and published in vivo data. This comparison suggests that results of in vitro methods are comparable to in vivo data and may provide greater sensitivity for respiratory toxicity studies of gaseous contaminants.

An experimental in vitro model for dynamic direct exposure of human cells to airborne contaminants

The aim of this study was to establish a dynamic in vitro model for direct exposure of human cells to gaseous contaminants to investigate the cellular responses to airborne chemical exposures. Nitrogen dioxide (NO2) was selected as a model gas compound. Standard test atmospheres were generated (2.5-10 ppm), using a dynamic direct dilution method. Human cells including: A549 pulmonary type II-like epithelial cell lines and skin fibroblasts were grown on porous membranes. Human cells on snapwell inserts were placed in horizontal diffusion chambers and exposed to various airborne concentrations of NO2 directly at the air/liquid interface for 1 h at 37 degrees C. Cytotoxicity of the test gas was investigated using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium), NRU (neutral red uptake) and ATP (Adenosine triphosphate) assays. Dose-dependent effects of NO2 were observed in human cells tested which resulted in a significant reduction of cell viability at concentrations normally encountered in workplace environments (p<0.05). Our findings suggest that the dynamic direct exposure method can be used for in vitro inhalational and dermal toxicity studies and potentially as an advanced technology for biomonitoring of airborne contaminants in future occupational and environmental toxicity assessments.

A novel in vitro exposure technique for toxicity testing of selected volatile organic compounds

Exposure to vapours of volatile chemicals is a major occupational and environmental health concern. Toxicity testing of volatile organic compounds (VOCs) has always faced significant technological problems due to their high volatility and/or low solubility. The aim of this study was to develop a practical and reproducible in vitro exposure technique for toxicity testing of VOCs. Standard test atmospheres of xylene and toluene were generated in glass chambers using a static method. Human cells including: A549-lung derived cell lines, HepG2-liver derived cell lines and skin fibroblasts, were grown in porous membranes and exposed to various airborne concentrations of selected VOCs directly at the air/liquid interface for 1 h at 37 degrees C. Cytotoxicity of test chemicals was investigated using the MTS (3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium) and NRU (neutral red uptake) assays following 24 h incubation. Airborne IC(50) (50% inhibitory concentration) values were determined using dose response curves for xylene (IC(50)=5350+/- 328 ppm, NRU; IC(50)=5750+/- 433 ppm, MTS in skin fibroblast) and toluene (IC(50)=0 500+/- 527 ppm, NRU; IC(50)=11,200 +/- 1,044 ppm, MTS in skin fibroblast). Our findings suggest that static direct exposure at the air/liquid interface is a practical and reproducible technique for toxicity testing of VOCs. Further, this technique can be used for inhalational and dermal toxicity studies of volatile chemicals in vitro as the exposure pattern in vivo is closely simulated by this method.

The toxicology of chlorine

Chlorine is a reactive gas used by humanity for over two centuries. Exposure to chlorine has occurred in a number of situations, including as a chemical warfare agent, in industrial and domestic exposures, and as a result of accidents and spills. The toxicology of chlorine is related almost entirely to effects in the respiratory system. A consistent symptomology occurs in both animals and humans. This ranges from sensory irritation, to irritation and bronchospasm, to cellular changes to bronchioles and alveoli, to development of pulmonary disease. While full recovery from such injuries remains the most likely outcome, there is little doubt that permanent loss of function is possible in severe cases. In all industrial applications of chlorine, occupational exposures to chlorine should be controlled to at least the recommended exposure standard. However, a focus of activity on ensuring that excursions (such as leaks or "gassing" incidents) above these values do not occur is likely to be more beneficial. Treatment of chlorine exposure is essentially symptomatic, with the efficacy of some treatments (such as corticosteroid therapy) still not well established.

Incompatibilities of chemicals

Chemical incompatibilities are potentially significant problems where hazardous chemicals are found. A number of chemical segregation systems have been developed which provide recommendations for the separation of incompatible chemicals. Three segregation systems were identified in this study: the UN Dangerous Goods system (which uses physical hazard as the main reason for segregation and has 14 categories), the US CHRIS system (which uses chemical reactivity and has 24 categories) and a third system which uses environmental risks (and has 25 categories). These systems were combined. Merging of each system was initially problematic, but became considerably easier once certain characteristics had been defined (such as flammability or water incompatibility). This gave a final merged incompatibility table containing 100 different segregation groups. This research study showed that it was possible to combine different segregation systems based on different criteria and that more comprehensive segregation systems can be developed. These can be of use in the decision-making process about where groups of chemicals may be used, and during the use of chemicals, where chemicals should not be combined. The use of more comprehensive segregation systems will also assist in developing proper measures for their control.

Integrating OHS, environmental, and quality management standards

A number of ideas, concepts and systems have emerged over the past 50 years, attempting to offer insights into improving the effectiveness of contemporary management. Many of these have become part of the management landscape. With the continuing publication of standards for (among others) quality, environment and safety management of Integrated Management Systems (IMS) offers efficiencies in management processes that are intuitively logical but on occasion, frustratingly illusive. The development of an IMS is sometimes carried out for the wrong reasons, and often with unforeseen consequences. The establishment of an IMS should not be taken lightly and should include lengthy design, considered consultation, flexible redesign, and staged implementation. However, once in place, an IMS offers the potential of a unifying approach for dealing with management systems.

Assessment of fogging resistance of anti-fog personal eye protection

The propensity for occupational eye protectors to fog in warm and moist conditions is often offered as a reason by workers not to wear occupational eye protection even where mandatory eye protection areas have been specified. A study of eye protection practices in the New South Wales coal mining industry identified the number one issue in underground coal mine conditions as being fogging of eye safety wear. Conventional anti-fog treatments and cleaners were considered by the miners as completely inadequate in these conditions. At the time of the study claims were being made for a new generation of lens treatments. These merited evaluation. Spectacles and goggles claimed to be fog resistant were obtained from manufacturers and suppliers and subjected to the test set out in BS EN 168 and the compliance criterion of BS EN 166. Some lenses claimed to be fog resistant failed the requirement, some new technology lenses showed arguably superior performance but failed the criterion of the standard. Modifications to the test procedure of BS EN 168 and acceptance criteria of BS EN 166 are proposed.

Human cell line toxicity of binary and ternary chemical mixtures in comparison to individual toxic effects of their components

Contaminated site projects involve health risk assessment procedures that must consider potential interactive effects of present contaminants. In order to establish a quick and reliable method that accounts for smaller than additive, additive, or greater than additive toxic effects, this study compared the cytotoxicity of 34 binary and ternary chemical mixtures of four structurally different chemicals to HeLa cells. Further, five blind samples of these mixtures or their components were tested to determine the ability to identify unknown mixtures. The colorimetric MTS in vitro cytotoxicity assay was used to detect cytotoxic effects after the cells were exposed for 1 h to serial dilutions of the mixtures. Experimental cytotoxicity data were compared and set against data predicted by a mathematical algorithm. They mainly showed additive effects of the components in mixture but also identified smaller than additive and greater than additive effects. A subjective classification scheme allowed evaluation of the toxicity of the blind samples in comparison to results from the study on binary and ternary mixtures tested before. This scheme focused on quantitative cytotoxicity data as well as on the slope of the concentration-effect curves and demonstrated the use of the MTS assay for human health risk assessments in the context of contaminated sites.

Using benchmarking to improve organizational communication

Best practice refers to those practices that lead to superior performance in a company or enterprise relative to industry or international leaders. Benchmarking of those activities that are critical to organizational performance is an important part of the identification and implementation of best-practice approaches. This article looks at communication as one aspect in the development of best practice in the management of safety, environment, and quality. A number of barriers to effective communication are identified, and benchmarks for the evaluation of organizational communication are suggested.

Integrating training systems for occupational health and safety, quality and environmental management

Quality, occupational health and safety, and environmental issues are three key areas that, along with productivity and service, must be managed effectively. Organizations face the need to develop integrated systems for the management of these areas. As organizations increasingly need to seek efficiencies, one field in which such integration can bring considerable gains is training. The present paper examines how the requirements for training in different areas overlap and how an integrated training program may be developed.

Equinins in equine neutrophils: quantification in tracheobronchial secretions as an aid in the diagnosis of chronic pulmonary disease

Equinins are a closely related group of proteins found in equine neutrophil granules. They demonstrate proteinase inhibiting activity restricted to microbial proteinase K and subtilisin, and they also possess antibacterial and antiviral properties. Antiproteinase K activity was measured in tracheobronchial secretions (TBS) of horses with mild (n = 15), moderate (n = 30) and severe (n = 16) chronic pulmonary disease, to determine its usefulness as an indicator of severity of disease and to measure neutrophil content. Determination of proteinase K inhibiting activity was based on a colorimetric assay measuring the suppression of 4-nitroaniline liberation from the synthetic substrate succinyl-L-alanyl-alanyl-alanin-4-nitroanilid, a process mediated by proteinase K. Proteinase K inhibiting activity proved to be a valid and simple indicator for assessing neutrophil content in TBS and a useful parameter to determine the severity of chronic pulmonary disease in the horse.

Use of EC criteria for determining health and environmental hazards for classification of chemicals for environmental risk

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The sensitivity and specificity of the MTS tetrazolium assay for detecting the in vitro cytotoxicity of 20 chemicals using human cell lines

A number of studies reported that the MTS in vitro cytotoxicity assay is a convenient method for assessing cell viability. The main features found with this assay are its ease of use, accuracy and rapid indication of toxicity. It might well be a useful tool in human health risk assessment if it can be shown that this assay also has an acceptable sensitivity and specificity. This is of interest particularly when exposure to unknown chemical substances requires the rapid detection and evaluation of toxic effects. In this study, the cytotoxicity of 20 chemicals selected from the MEIC priority list was determined with the MTS assay. Since it could be shown that interactions between detection reagents and test chemicals might influence the results of this assay, preliminary experiments were carried out such that artifactual results due to test chemical interference could be excluded from this study. IC50 (50% inhibitory concentration) were established for each test chemical in two human cell lines (F1-73 and HeLa) and later compared with published toxicity data of the same chemicals established with in vitro and in vivo toxicological test systems. Direct comparisons of the data showed a generally lower sensitivity of the MTS assay, which is influenced by biological test organisms, cell type and exposure time. In terms of the specificity of the MTS assay, the results showed a good correlation between data obtained with the MTS assay and published data. The lowest correlation was found when the MTS assay was compared with in vivo studies, however, this finding corresponds well with other published in vitro-in vivo correlations. The highest correlation was found when the MTS assay was compared with test systems using human cell lines or exposure times of 3-24 h. Since the sensitivity of the MTS assay might be increased using different cell types or by extended incubation, this assay is found to provide ideal features of a good measurement system that might also be used for on site toxicological assessments.

Occupational health and safety management systems

There is a need for OHS management systems that can be integrated with systems for the management of other organizational priorities including quality, environment, productivity, and the like. The present article presents an overview of the draft Australian/New Zealand Standard on Occupational Health and Safety Management Systems as a step toward the development of such integrated systems. This draft standard presents a five-stage process of OHS management. The five stages--commitment and policy, planning, implementation, measurement and evaluation, and management review and improvement--will create a cycle of activity that can lead to the continual improvement of processes and systems for OHS management in the workplace.

Pumice slurry as a crossinfection hazard in nonclinical (teaching) dental technology laboratories

This research sought to compare the microbiological status of pumice slurry in clinical and nonclinical dental laboratories. Samples were inoculated onto selective and nonselective media. Resultant colonies were counted and identified to genus or species level. In the nonclinical laboratory, counts were constant at approximately 10(7) to 10(8) cfu/g. Pseudomonads, staphylococci and Bacillus spp comprised the major pumice contaminants in both laboratories. It was concluded that nonclinical laboratories are not immune from the presence of potentially pathogenic microorganisms in pumice slurry. Disinfection reduces contamination by oral microorganisms.

Integration of occupational health and safety, environmental and quality management system standards

Occupational health and safety, environmental, and quality (SEQ) issues are commonly managed by three separate departments within organizations. Because of a number of commonalities in the three management systems, there could be a degree of overlap that might lead to inefficiencies. By integrating these three management systems into one SEQ system, the duplication of effort could be minimized and the health and safety, environmental, and quality issues could be managed by one common proactive approach. The draft Australian standard for an occupational health and safety (OHS) management system and the internationally accepted standards for environmental (ISO 14001) and quality (ISO 9001) management systems were analyzed to identify all requirements of the three management systems and integrate this into one SEQ management system standard.

Integrating quality, safety, and environment management systems

Internationally consistent ISO standards are in use, or are being developed, for quality systems, environmental management, and occupational health and safety. These standards outline a model for the management of quality, environment or safety. In many respects the process of developing management systems for these matters contains a number of common elements, including obtaining commitment from senior management; instituting consultative mechanisms; developing a policy; identifying components of the management program; resourcing, implementing, and reviewing the program; and integrating the program into the organization's strategic plan. The necessity of developing separate management systems for different organizational aspects is wasteful and inefficient. Better management systems will be developed if they are integrated into a single management structure.

Frequency and occurrence of LD50 values for materials in the workplace

The main routes of occupational exposure for chemicals encountered in occupational environments are by skin contact and by inhalation. Acute toxicity data were collected for all chemicals with Australian Exposure Standards. For the 582 chemical entities, data were available as follows: oral toxicity (364, 63%), dermal toxicity (154, 26%) and inhalational toxicity (171, 29%). No acute toxicity data were available for 177 of these chemicals (177, 30%). Chemicals with data for more than one acute toxicity test were limited to: oral/dermal (151, 26%), oral inhalation (131, 23%), dermal/inhalation (73, 13%) and oral/dermal/inhalation (70, 12%). Analysis of subsets of groups of chemicals indicated that toxicity data were available for many pesticides and organic chemicals, but not for inorganic chemicals. The lack of acute inhalational and dermal toxicity data for chemicals used extensively enough to warrant exposure standards is at variance with the amount of toxicity information for other categories of chemicals (e.g. agricultural chemicals, therapeutic substances and food additives). This may also indicate scant regard given to toxicological information in the exposure standard setting process.

Ultrasonographic findings in cows with cholestasis

Four cows with cholestasis, whose general condition was moderately to severely disturbed, were examined. Two of them had signs of colic, and one had severe pruritus. All of them had jaundice and three had dermatitis solaris. Bilirubinuria occurred in three of the cows and they all had increased concentrations of serum bilirubin and serum bile acids and increased activities of hepatic enzymes. An ultrasonographic examination of the liver and gallbladder revealed that in one cow only the extrahepatic bile ducts were dilated, in another only the intrahepatic bile ducts were dilated and in the other two both the intrahepatic and extrahepatic bile ducts were dilated. In three of the cows the gallbladder was severely dilated and the wall was thickened. Ultrasonographically, the bile appeared either anechoic or echogenic. Surgical or post mortem examinations revealed that the cholestasis in one cow was attributable to obstruction of the common hepatic duct in the area of the hepatic hilus, in two it was caused by obstruction of the common bile duct near the duodenal papilla, and in the fourth cow, the common bile duct was compressed by adhesions, resulting from peritonitis, which involved the liver, gallbladder and abdominal wall.

Best practice in workplace hazardous substances management

Chemical-induced injury and disease remains a significant problem in workers in industry. As a result of this problem, a number of national and international initiatives have recommended the development of conventions, regulations, and codes of practice to attempt to deal with the problems of hazardous substances at work. Within Australia, workplace hazardous substances regulations are in development which will impose legal obligations and responsibilities on the suppliers of hazardous substances and on the employers who use them. At the same time, internationally consistent ISO standards are in use, or are being developed, for quality systems, environmental management, and occupational health and safety. These standards outline a model for the management of quality, environment, or safety, and the processes involved are applicable to the management of hazardous substances. This process includes: obtaining commitment from senior management; instituting consultative mechanisms; developing a hazardous substances policy; identifying components of the hazardous substances management program; resourcing, implementing, and reviewing the program; and integrating the program into the organisation's strategic plan. Only by blending in a specific management program for hazardous substances into the overall planning of an organization will they be managed effectively and efficiently.

Classification of hazardous materials by oral, dermal, and inhalational toxicities

Currently, no toxicity classification system exists in any formal sense for dermal and inhalational toxicities (the main routes of exposure in occupational environments), and, different criteria are used by regulatory agencies in the classification of toxicity by these routes. Therefore, a comparison of the acute toxicity information available for 582 chemicals with exposure standards was made with a view to establishing such a toxicity classification system. By sorting data on the basis of oral toxicity values, and dividing these values into toxicity classes (such as slightly toxic, very toxic, supertoxic), a strong correlation was found to exist between oral and dermal toxicity values, and oral and inhalational toxicity values. Indeed, overlap across toxicity classes was very small, and in most cases, clear demarcations existed. A toxicity classification system is proposed from these data. This classification system is based on a comparison of actual toxicity data, and is a true reflection of the interrelationships between oral, dermal, and inhalational toxicities.

Workplace toxic incident notification: results of a survey of 16 factory sites in western Sydney

Workers in the chemical industry are often employed where there is a potential for significant exposure to hazardous materials. Many of these events go unrecorded and are not notified to agencies charged with the responsibility of regulating the workplace. Therefore, a survey was conducted of factories covering a range of activities where poisonous chemicals are in use, aimed at proactively reviewing toxic incident reporting, including (i) underlying principles of notification, (ii) any relevant criteria used in the reporting of incidents, and (ii) compliance with existing legislation. Sixteen factories in the Western Sydney area were inspected by a government safety inspector over a 4-month period. Forty-eight employees were interviewed and data describing 46 exposure events were obtained covering a 12-month period. In all, 10 incidents were identified as significant exposure events, with 5 events (11% of total) at 5 different factories (31% of sites inspected) involving 8 workers (17% of workers interviewed) being definite breaches of statutory accident reporting requirements. The survey revealed a failure by employers to notify significant toxic exposure events due to reluctance or ignorance and or lack of clarity of occupational health and safety regulations. It also revealed that substantial numbers of workers are exposed to incidents involving poisonous materials, and that with this nonnotification, regulatory agencies are largely unaware of their magnitude.

Some toxicological issues in chemical safety and regulation in an Australian context

This article considers the potential effects on the human body of toxic hazardous substances in general, along with advanced methods of detecting short- and long-term effects of exposure with reference to the results of recent research. In addition to occupational exposure, other contributors to an individual's overall toxic exposure load including environmental and home and lifestyle exposures are also considered in detail. Toxicological information (from diverse sources) and an awareness of the limitations of our present state of knowledge of toxicology are concluded to be important factors in developing chemical safety and regulatory criteria. Although there is some debate concerning the adequacy of the exposure standard-setting process, TWA measures are capable of giving reliable indications of the efficacy of control measures and procedures. Electroencephalogram (EEG) activity reflecting stimulus attention and decision time, electromyography measuring nerve conduction velocities, reaction time, and neuropsychological performance-using batteries of psychometric tests, may all be effective indicators of exposure, interaction with other factors, and long-term effects of exposure.

A prospective cohort study of the chronic effects of solvent exposure

The issue of the health effects of long-term exposure to solvents still attracts considerable debate, particularly among regulators and policymakers. This is especially true for studies of neurobehavioral effects. A major reason for this debate is that cross-sectional research designs are almost universally used in this area. Cross-sectional studies suffer from problems of possible confounding by a range of unknown factors and also usually from poor estimates of exposure. This study is an attempt to solve this problem by using an inception cohort design in which the subjects are measured at the beginning of their exposure and then at intervals while their exposure continues. Two hundred first-year apprentice vehicle spray painters were entered into the study within 6 months of beginning their apprenticeship together with a comparison group of 76 first-year apprentice electricians and 49 first-year apprentice metal fabricators. Measures of neurobehavioral function using a test battery based on an information-processing model were made at study entry and will be made annually. In addition apprentice's assessments of their own exposure are being made annually and compared with workplace-exposure assessments. So far measures have been made at the beginning of the second year for the entire cohort and at the beginning of the third year for one-third of the cohort. This paper is a description of the results for this one-third. The results suggest that there were no significant changes in neurobehavioral function in the first 2 years of exposure to solvents. However, the results of workplace monitoring suggest that exposure is considerably below current exposure standards for solvents during this time.

The genotoxicity of lead

Lead has been tested for genotoxic potential in a range of mutagenicity assays. Such studies report varying effects, and the results are equivocal. The reasons for this may be related to problems of the solubility of many lead compounds, their inability to dissolve in biological fluids, chemical interferences resulting in conflicting observations, the nonspecificity of the assays used, the delivery of toxic doses to specific genetic processes or the mediation of genotoxicity through indirect mechanisms. Occupational and environmental exposures to lead have also been associated with increases in chromosomal damage in humans at moderate to high exposures, although this evidence is contradictory. Where positive findings have been reported, many are related to exposure. The possibility that lead is genotoxic is by no means clear, but evidence is still accumulating.

Solvent exposure and related work practices amongst apprentice spray painters in automotive body repair workshops

As part of a multidisciplinary study into the health effects of solvents, workplace assessments and airborne solvent vapour monitoring was conducted in 46 spray painting workshops in the Sydney metropolitan area. Breathing-zone samples were taken from 50 apprentices and 14 experienced spray painters. An interview schedule was developed to obtain information about the use of acrylic or two-pack paint systems, the use of engineering controls, the use of personal protective equipment and the availability of material safety data sheets. Contaminants typical of the chemical products used in this industry were encountered (aromatic hydrocarbons, C5-C7 aliphatic hydrocarbons, ketones, esters). The results of airborne solvent monitoring indicate a total solvent exposure in the range 1-99% of a combined Worksafe Australia exposure standard, with a mean of 19%. Solvent exposure was highest when spraying acrylic paint in the open workshop and lowest when spraying two pack paint in a spray booth. Much the same personal protective equipment was available in all workshops, but wide variation in its use was observed. Material safety data sheets were not observed in any of the workshops.

Expression of procoagulant activity by equine lung macrophages: stimulation by blood lymphocytes

Increases in procoagulant activities (PCA) in equine lung macrophages were induced by non-adherent blood lymphocytes which were prestimulated with phytohaemagglutinin for 48 to 72 hours or by supernatants harvested from prestimulated blood lymphocyte cultures. However, prestimulated lymphocyte suspensions themselves expressed PCA which was most probably derived from contaminating monocytes. Because non-adherent cells from lymphocyte suspensions may have attached to adherent macrophages, cells within lymphocyte suspensions might have contributed to the PCAs expressed by lymphocyte-stimulated lung macrophages. Stimulation of lung macrophages for 24 hours by supernatants of phytohaemagglutinin-prestimulated blood lymphocytes induced a significantly greater PCA increase than stimulation by phytohaemagglutin alone. Thus, cytokines from lymphocyte cultures might have triggered or enhanced PCA induction. Direct stimulation of lung cell preparations with phytohaemagglutinin for 48 hours resulted in a progressive increase of PCA in only two of five specimens tested. The failure to induce PCA in three specimens could be due to the absence of sufficient numbers of T cells within the adherent lung cell preparations. In conclusion, PCA response of equine lung macrophages might be lymphocyte-stimulated in which case PCA might be a useful tool for monitoring the processes of cell-mediated immunity in horses.

Neutrophil migration induced by equine respiratory secretions, bronchoalveolar lavage fluids and culture supernatants of pulmonary lavage cells

Supernatants of equine respiratory secretions enhanced the migration of equine neutrophils into the lower compartments of Boyden chambers. Checkerboard analysis revealed that the neutrophil migration promoting activity (NMPA) of secretion specimens was in great part caused by chemokinesis, irrespective of the neutrophil score of the specimen. The NMPA of respiratory secretions was correlated neither with the neutrophil score of the secretion specimen nor with the severity of the chronic pulmonary disease. Respiratory secretions collected while horses were kept under low dust or under dusty housing conditions induced migration of neutrophils in the same order of magnitude. The number of migrated neutrophils and the procoagulant activity (PCA) within respiratory secretion specimens was positively correlated; however, the meaning of this finding is not yet clear. None of the nine cell-free supernatants of bronchoalveolar lavage fluid, which were assayed undiluted, induced significant neutrophil migration, although some samples contained up to 4.0 x 10(5) neutrophils/ml. In vitro culture of lung lavage cells, which mainly comprised macrophages and lymphocytes, without stimulation or with the addition of low doses of phytohemagglutinin (PHA) resulted in the secretion of NMPA which was in great part chemotactic. However, culture supernatants of lung cell preparations which were stimulated by lipopolysaccharide (LPS) or by PHA-prestimulated lymphocytes reduced the migration of neutrophils compared with the supernatants of control cells. NMPA within culture supernatants had a highly significant negative correlation with the PCA of macrophages within the lung cell preparations. Our results imply that a complicated and sophisticated regulation underlies neutrophil accumulation within the airways of horses affected with chronic pulmonary disease. Future experiments are required to assess the biological significance of the factors modulating neutrophil migration which are present in the respiratory secretions and in the culture supernatants of equine lung lavage cells.

Spontaneous and lipopolysaccharide-induced expression of procoagulant activity by equine lung macrophages in comparison with blood monocytes and blood neutrophils

The procoagulant activity (PCA) associated with equine bronchoalveolar lavage cells was determined and compared with that expressed by peripheral blood mononuclear cells and neutrophils. Lung cell preparations from horses affected with chronic pulmonary disease were included in all experiments and there was no difference in the qualitative type of response compared with lung cells which were obtained from healthy horses. Significant amounts of PCA were expressed by cells freshly procured from bronchoalveolar lavages of healthy and diseased horses. When adherent lung cells were kept in culture for some time, cell-associated PCA slightly decreased within 4 h, reached its lowest point after approximately 24 h and rose again during the second week of culture. In contrast, freshly isolated blood mononuclear cells or neutrophils expressed little PCA. Following culture for 24 h, mononuclear cells began to express increased PCA levels. Both cultivated lung cells (comprised mainly on alveolar macrophages) and blood mononuclear cells responded to LPS by dramatically increased PCA expression, whereas neutrophils showed a small augmentation of PCA on LPS stimulation. Fresh mononuclear cells and cultivated lung cells differed in their PCA response to LPS in several respects. Blood mononuclear cells were more sensitive to LPS than lung macrophages and responded to a 100-fold lower LPS concentration than the latter. Mononuclear cell-associated PCA peaked 4 h after stimulation whereas that of cultured macrophages continued to increase up to 24 h after stimulation. Lung macrophages cultured in adherence responded to LPS stimulation with a much higher PCA increase than macrophages cultured in suspension, in teflon containers. However, the culture vessel did not influence the PCA expressed by unstimulated cells. PCA expression depended to a large extent on transcription and translation, as evidenced by a 60-85% reduction of PCA in cycloheximide- or actinomycin D-treated, LPS-stimulated lung macrophages. PCA was largely cell-associated; only a small proportion of cell-associated PCA was shed into the medium. The PCA associated with mononuclear cells and with lung macrophages was tissue factor because of its dependence on clotting factor VII and its independence from clotting factor VIII. The expression of PCA by freshly isolated cells, the lower sensitivity to LPS, and the loss of PCA in the first 24 h of cultivation are indicative of in vivo activation of lung macrophages.

Separation of equine bronchopulmonary lavage cells by density gradient centrifugation and expression of procoagulant activity in unpurified cells and cell subpopulations

Bronchopulmonary lavage was performed in 10 healthy horses and in 39 horses with chronic pulmonary disease. The predominant cell types were macrophages in healthy horses and neutrophils in severely diseased horses. Procoagulant activity (PCA) was detected in all 32 cell-free supernatants examined and in all 49 unpurified cell suspensions. Cells were separated by centrifugation on discontinuous gradients prepared either with Percoll or with Metrizamide. Macrophages were enriched in subpopulations of low density. Neutrophils could not be purified by density gradient centrifugation using either gradient medium. PCAs of cell subpopulations were plotted against their respective macrophage, neutrophil, and lymphocyte content. PCA was positively correlated with macrophage content (P less than 0.001) and negatively correlated with neutrophil (P less than 0.02) and lymphocyte (P less than 0.001) content. Therefore, PCA of equine lung cells most likely originates from macrophages as shown in other species. The density shift of lung neutrophils requires further investigation.

A fresh start. Report of a one-day workshop on occupational asthma in the aluminium industry

The workshop was successful from a number of viewpoints. It achieved the general goal of a greater understanding of respiratory problems in the aluminium industry. A free exchange of information and attitudes occurred. While the prevalence of asthma was not high compared with other occupational asthmas, it was noteworthy. The industry had embarked on a programme for the development of standard criteria of diagnosis and of the collection of statistics that related to the condition. Some concerns remain. It is to be hoped that further developments will be derived from the workshop, including opportunities for research and for a better understanding of the occupational-health issues and practices in the primary aluminium industry in Australasia.

Procoagulant activity in respiratory tract secretions from horses with chronic pulmonary disease

Cell-free supernatants (sol phases), obtained after centrifugation (50,000 x g for 45 minutes) of respiratory tract secretions from horses with chronic pulmonary disease, were assayed for procoagulant activity (PCA) in a one-stage clotting assay. Of the 103 specimens tested, 59% (61) contained PCA. Procoagulant activity was detected most often in respiratory tract secretions of severely affected horses and was correlated with the quantity of neutrophils in the respiratory tract secretions. In 12 of the 17 secretions tested, the clotting time was decreased in a dose-dependent manner. However, in the coagulation assay, some reversal of PCA or inhibition of coagulation was observed in 4 secretion specimens when greater volumes of sol phase were added. Procoagulant activity was characterized tentatively as tissue factor, because it was temperature stable and was inhibited by phospholipase C and by concanavalin A. Clotting was induced in factor VIII-deficient human plasma; however, with the exception of 1 respiratory secretion specimen, clotting was not enhanced in factor VII-deficient human plasma. Procoagulant activity is a useful indicator of airway inflammation.

Putative serotonergic bipolar and amacrine cells in the chicken retina

Four populations of putative serotonergic cells could be detected in the chicken retina by histofluorescence and immunohistochemistry. Numerous (10,000/mm2) small (6 micron diameter) bipolar cells were located towards the middle of the inner nuclear layer, as were sparser (1000/mm2) larger (12 micron diameter) amacrine cells. Very sparse large (greater than 30 micron diameter) and more numerous small (12 micron diameter) ganglion cells were also detected. Prominent fibre plexuses were detected in the inner plexiform layer, close to the inner nuclear and ganglion cell layers, and appeared to be formed by the processes of the bipolar cells, amacrine cells and at least the large ganglion cells. Exogenous serotonin (5-HT) was detected in the chicken retina. From the effects of neurotoxins on 5-HT levels and 5-HT-like immunoreactivity (5-HTLI), most of this appeared to be associated with the amacrine cells. 5-HTLI bipolar cells were selectively destroyed by intravitreal injections of 5-10 nmol of kainic acid, while 5-HTLI amacrine cells were destroyed by N-methyl-D,L-aspartic acid and 5,7-dihydroxytryptamine. The sensitivity of the bipolar cells to kainic acid indicates that they are OFF-cells.

Influences of endogenous dopamine on carotid body discharge and ventilation

Ventilatory and carotid body responses to hypoxia have been related to the endogenous release of dopamine by use of the antagonist drug haloperidol. The published studies have produced conflicting data for ventilation. However, antagonist drugs can act at multiple anatomical sites, on multiple pharmacological receptors, often at different dosages, and have nonspecific actions at high dosage. For these reasons, we have undertaken a systematic study of haloperidol dose-response curves with particular emphasis on the lowest possible concentrations of drug. In five cats anesthetized with pentobarbital sodium (30-35 mg/kg), single- or few-fiber afferent recordings of the carotid body showed that haloperidol increased the discharge during both basal and asphyxic conditions, the increments being proportional to haloperidol dosage (0.1-1,000 micrograms/kg). Increments of ventilation were also produced, these increments increasing only over the lower range of dosage; at the highest haloperidol dosage, the dose response showed a tendency to plateau or inflect downward, suggesting the appearance of an opposing inhibitory mechanism.

The experimental administration of lead to rats in neuropathological and behavioural studies

The experimental investigation of the effects of lead have been studied for nearly 20 years. In that time, a variety of neurobiological processes have been reported to be altered following ingestion of lead. Most routes of administration and a bewildering number of doses have been employed to administer lead to experimental animals. However, inadequate characterization of dose regimes has impaired understanding of any effects, and their correlation to conditions of human exposure. As an index of lead burden, blood lead remains the most reliable means of assessing recent lead absorption. It is clear that a large number of model systems and dosing regimes do not address the problems of human clinical or subclinical lead intoxication. It is also clear from brain lead measurements in experimental animals that lead is selectively sequestered into specific areas of the control nervous system.

Effect of lead exposure on dopaminergic D2 receptor binding in the 21-day-old rat

The effect of lead on dopaminergic D2 receptor binding, as measured by butaclamol-displaceable [3H]domperidone binding, was studied in the 21-day-old lead-dosed rat. Maternal rats were dosed with 300 ppm and 1000 ppm Pb in drinking water from conception to weaning as previously described [1]. Samples of limbic forebrain and striatum were taken from 21-day-old offspring and assayed for dopamine D2-receptor binding, as outlined by Lazareno and Nahorski [2]. There was a significant (P less than 0.05) decrease in body weight in the animals from which limbic forebrain samples were taken. There were no other significant effects of lead on body- or brain weight. Dopaminergic D2 receptor binding was unaffected by lead administration. These preliminary findings show that dopamine D2 receptor binding is not affected by lead at the doses and exposures used.

Low-level lead exposure alters morphine antinociception in neonatal rats

Administration of lead (at 300 and 1000 ppm) in the maternal drinking water from conception to weaning impaired the antinociceptive activity of morphine in 10-day-old neonatal rats. Blood lead levels in these animals were below 50 microgram/100 ml in the high lead dose group and below 35 microgram/100 ml in the low lead dose group. The differences in the antinociceptive potency of morphine between normal and lead-exposed animals were not observed at later time points (21 and 30 days). It is suggested that lead disrupts the development of opioid receptor systems in the central nervous system and that this disruption occurs early in development.