Biological aspects of occupational exposure to cadmium and several other metals

We have performed several cross-sectional epidemiological surveys among workers exposed to cadmium, mercury vapour or manganese in order to assess : their early biological or functional effects; the biological tests allowing an assessment of the amount of metal absorbed or stored in the body; the acceptable exposure levels. Studies have also been carried out among persons exposed to inorganic arsenic in order to define its inactivation mechanism and to develop a biological test of exposure. The kidney is the main critical organ following long-term exposure to cadmium. To prevent the occurrence of renal changes in the majority of male workers exposed to cadmium, its concentration in renal cortex should not exceed 215 micrograms/g (wet weight), and that in urine : 10 micrograms/g creatinine. A blood cadmium level of 1 microgram/100 ml has been suggested as maximum tolerable level for long-term exposure. Prolonged exposure to mercury vapour may lead to renal and neurological disturbances. The preclinical signs of nephrotoxicity are correlated with the amount of mercury absorbed which may be assessed by monitoring the mercury level in urine. The neurotoxic effects (particularly tremor) are mainly related to the integrated exposure (duration and intensity). A maximal permissible level of 50 micrograms Hg/g urinary creatinine is proposed to prevent the occurrence of these toxic effects. An exposure to manganese dust for 7 years on the average at a level below the maximum allowable airborne concentration (5 mg/m3) recommended by the ACGIH in the USA may still lead to a slight reduction in psychomotor and spirometric performances and interfere with calcium metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)     

The safety of prenatal ultrasound exposure in human studies

Diagnostic ultrasound use in obstetrics has been growing rapidly to become an integral part of prenatal care today. The high proportion of exposure to prenatal ultrasound highlights the public health significance of routine ultrasound use. A majority of epidemiologic studies tends to support the safety of diagnostic ultrasound use during pregnancy. However, there have been some reports that there may be a relation between prenatal ultrasound exposure and adverse outcome. Some of the reported effects include growth restriction, delayed speech, dyslexia, and non-right-handedness associated with ultrasound exposure. Continued research is needed to evaluate the potential adverse effects of ultrasound exposure during pregnancy. These studies should measure the acoustic output, exposure time, number of exposures per subject, and the timing during the pregnancy when exposure(s) occurred, while controlling for potential confounding variables such as sociodemographic, medical, and obstetric risk factors. We recommend that a new consensus development conference be held to gather the needed data and provide guidelines for the future research needs, as well as respond to the rapid advances in this technology.     

Biological versus ambient exposure monitoring of creosote facility workers

Traditional methods for monitoring occupational creosote exposure have focused on inhalation. However, there is evidence that dermal exposure contributes importantly to total systemic dose, as measured by biological monitoring methods. This study was conducted to further characterize the relationships between inhalation and dermal exposures to creosote, and to compare traditional ambient exposure monitoring versus biological monitoring in 36 creosote-exposed wood treatment workers. Full-shift personal air samples were obtained, along with post-shift and next-day urine measurements for 1-hydroxypyrene. There was little or no correlation between airborne measures and urinary 1-hydroxypyrene (r2 = 0.05 to 0.35). More than 90% of 1-hydroxypyrene could be attributed to dermal exposure. These data indicate that traditional monitoring methods may be inappropriate for creosote workers, raising concerns about the adequacy of methods currently mandated by the Occupational Safety and Health Administration.     

Lauriston S. Taylor Lecture: Assuring the safety of medical diagnostic ultrasound

In 1980, the NCRP formed Scientific Committee 66 with an assignment to address the subject of "biological effects of ultrasound and exposure criteria." It was recognized that the primary source of exposure to ultrasound was through medical applications and, especially, through procedures employing diagnostic ultrasound. While the risk to patients from these procedures was believed small, it was considered important for users to understand it, in view of the widespread use of diagnostic ultrasound. In proceeding with this assignment, much emphasis has been given to the mechanisms by which ultrasound can bring about changes in biological structures or processes. Thermal effects are possible; the local temperature can rise especially rapidly where ultrasound impinges on bone. From theory for heat production and transport, and by analysis of experimental results with mammals, information has been obtained for guiding users in avoiding harm from temperature elevation. Nonthermal effects, such as capillary rupture, can occur when ultrasound is incident on tissue that normally contains gas-filled cavities, as in adult lung or intestine, or on any tissue containing gaseous contrast agents. Theory from fluid dynamics, together with experimental findings, has led to quantitative guidance for avoiding damage from acoustically activated cavities. It is felt that good practice in applying diagnostic ultrasound is best assured by making it possible for users to be well informed on safety matters so that they can feel justifiably confident in making appropriate choices of operating conditions. A promising and useful approach is in the display of safety information on the diagnostic ultrasound screen, which is now a feature of United States standards.     

Exposure to fine airborne fibrous dust amongst processors of para-aramid

Laboratory studies with animals exposed to high concentrations of fine fibrous dust (fibrils) derived from para-aramid fibres suggest that it may cause lung damage. Based on the information from such studies there is an initiative in the U.K. to regulate workplace exposure. Para-aramid fibres are used in textiles, friction products, composite materials and other applications, but little is known about the extent or intensity of fibre dust exposure during these manufacturing operations. A survey has been undertaken in a selection of manufacturers of para-aramid containing products to assess their 8-h time-weighted average exposure to respirable fibrils. Concentrations were measured using the membrane filter technique with analysis by phase-contrast microscopy. Measurements of airborne fibril size were also made by scanning electron microscopy. Geometric mean concentrations for different jobs were generally low, ranging from 0.005 to 0.4 fibres ml⁻¹. Assuming a log-normal distribution, less than 1% of the exposure levels would be expected to exceed 0.5 fibres ml⁻¹ and about 0.002% would be above 2 fibres ml⁻¹. Analysis of a selection of samples by fluorescence microscopy suggests that most of the fibrils in the majority of sites surveyed were para-aramid. At some sites a significant proportion of asbestos fibres were also found.     

自聚焦超声在动物离体皮下脂肪组织中的融脂效应研究

目的：探索高频聚焦超声和低频聚焦超声在不同辐照时间和功率的条件下,对离体动物猪的皮下脂肪不同层产生生物学融脂效应的规律。方法：将离体动物猪脂肪生物实验分为两组,分别使用工作频率为6．5MHz和3MHz的换能器。两组使用的超声功率为2～5w,辐射时间为5S、10S、20S、4s、60s和80S;辐照后进行MTT检测脂肪细胞活性并计算融脂效应的面积。描述离体动物猪的皮下脂肪层生物学融脂效应,讨论不同条件下生物学融脂效应之间的区别。结果：随着超声功率和辐照时间的增加,脂肪组织形成融脂效应的程度呈规律性变化。辐照时间为5s时脂肪组织破坏不明显,辐照时间〉10s时脂肪组织则明显被破坏。相同超声功率和辐射时间条件下聚焦超声在深脂肪层的破坏程度比浅表脂肪层高。3MHz聚焦超声在辐射时间≥40s可穿过约5mm的表皮并凝固性破坏皮下不同层次的脂肪组织。结论：高频和低频聚焦超声均可有效破坏脂肪组织。     

薄膜分散-超声法制备BMPs磁性脂质体

目的 采用薄膜分散-超声法制备磁性颗粒(bacterial magnetic particles,BMPs)脂质体,考察BMPs浓度、超声功率和超声时间等因素对BMPs磁性脂质体粒径的影响.方法 薄膜分散-超声法制备BMPs脂质体,调节BMPs浓度、超声功率和超声时间等因素,激光散射粒度仪测定磁性脂质体粒径.结果 以薄膜分散-超声法制备的BMPs脂质体,BMPs浓度在(20～60)μg/mL时,磁性脂质体粒径基本稳定,平均94.9nm;BMPs浓度在(60～100)μg/mL时,磁性脂质体粒径随着BMPs浓度增加而有增大的趋势.超声功率的增加或超声有效时间增大时,磁性脂质体的平均粒径有减小趋势,当超声功率为300W、有效超声时间为100s时,粒径出现最小值;但其后都存在转折,随着超声功率的再增加或超声有效时间再增大时,平均粒径反而出现增大现象.结论薄膜分散-超声法制备BMPs脂质体,通过控制BMPs浓度、超声功率和超声时间等因素,可以对磁性脂质体粒径进行调节.     

An occupational hygiene investigation of exposure to acrylamide and the role for urinary S-carboxyethyl-cysteine (CEC) as a biological marker

Acrylamide has a range of toxicological hazards including neurotoxicity and reproductive toxicity; however, occupational risk management is driven by its genotoxic and carcinogenic potential (it is classified within the EU as a Category 2 carcinogen, R45 and Category 2 mutagen, R46). Since there is the potential for skin absorption and systemic toxicity, biological monitoring may be a useful aid for the assessment of exposure via inhalation, ingestion and dermal absorption. However, there are currently no biological monitoring guidance values (BMGVs). This study describes an extensive survey of potential workplace exposure to acrylamide at the Ciba (Bradford) site to gather data suitable for a BMGV. This manufacturing site is typical within the industry as a whole and includes a cross section of activities and tasks representative of acrylamide exposure. Acrylamide is used in the manufacture of polyacrylamide based products for applications in water treatment; oil and mineral extraction; paper, paint and textile processes. Workers (62 plus 6 controls) with varying potential exposures provided a total of 275 pre shift and 247 post-shift urine samples along with 260 personal air samples. A small non-exposed control group was similarly monitored. Urine samples were analysed for S-carboxyethyl-cysteine (CEC). Airborne, surface and glove samples were analysed for acrylamide. Inhalation exposures were well controlled with values consistently below one-tenth of the UK Workplace Exposure Limit. Engineering controls, personal protective equipment and work practice, all contributed to good control of occupational exposure. CEC was found in urine samples from both exposed workers and non-occupationally exposed controls. At the low levels of exposure found, smoking made a significant contribution to urinary CEC levels. Nevertheless a correlation between urinary CEC and airborne acrylamide was found. A mixed effects model incorporating inhalation concentrations of acrylamide and smoking habits could predict some of the variation in observed post-shift urine results but could be improved through the use of additional surface contamination data. However, the data does not suggest that dermal absorption was a major contributor to the systemic dose. Based on the 90th percentile of the data, inclusive of the effects of smoking and environmental factors, a value of 4 mmol mol(-1) creatinine is proposed as a pragmatic BMGV associated with good occupational hygiene practice and control of workplace exposure. CEC in urine analysis has the utility for routine use as a means to estimate biological uptake where there is a potential for significant exposure or loss of workplace control.     

How is cardiovascular disease mortality risk affected by duration and intensity of fine particulate matter exposure? An integration of the epidemiologic evidence

An integrated evaluation of representative epidemiological evidence provides interesting insights regarding how cardiovascular mortality risks are affected by exposure to fine particulate matter air pollution. The literature can be interpreted as indicating that cardiovascular health effects are dependent on at least two dimensions of cumulative exposure—the intensity of exposure and the duration of exposure. The empirical evidence is incomplete and there are substantial limitations related to literature-based cross-study comparisons. Nevertheless, the evidence suggests that there is a progressive approximately log reduction in the marginal increase in mortality risk for both dimensions of cumulative exposure. Longer duration exposure has larger, more persistent cumulative effects than short-term exposure, but the highest marginal effects occur with relatively short-term exposures most proximal in time. With regards to intensity of exposure, very steep, near-linear, exposure–response relationships are observed for low to moderate exposures and there is a flattening out or leveling off of the exposure–response function at very high exposures.     

Airborne Endotoxin Concentrations in Homes Burning Biomass Fuel

Background

About half of the world’s population is exposed to smoke from burning biomass fuels at home. The high airborne particulate levels in these homes and the health burden of exposure to this smoke are well described. Burning unprocessed biological material such as wood and dried animal dung may also produce high indoor endotoxin concentrations.

Objective

In this study we measured airborne endotoxin levels in homes burning different biomass fuels.

Methods

Air sampling was carried out in homes burning wood or dried animal dung in Nepal (n = 31) and wood, charcoal, or crop residues in Malawi (n = 38). Filters were analyzed for endotoxin content expressed as airborne endotoxin concentration and endotoxin per mass of airborne particulate.

Results

Airborne endotoxin concentrations were high. Averaged over 24 hr in Malawian homes, median concentrations of total inhalable endotoxin were 24 endotoxin units (EU)/m³ in charcoal-burning homes and 40 EU/m³ in wood-burning homes. Short cooking-time samples collected in Nepal produced median values of 43 EU/m³ in wood-burning homes and 365 EU/m³ in dung-burning homes, suggesting increasing endotoxin levels with decreasing energy levels in unprocessed solid fuels.

Conclusions

Airborne endotoxin concentrations in homes burning biomass fuels are orders of magnitude higher than those found in homes in developed countries where endotoxin exposure has been linked to respiratory illness in children. There is a need for work to identify the determinants of these high concentrations, interventions to reduce exposure, and health studies to examine the effects of these sustained, near-occupational levels of exposure experienced from early life.     

Survey of ultrasound therapy devices in Manitoba

In 1982 a survey was performed of 89 ultrasound therapy devices in use in medical and paramedical organizations in Manitoba. Field measurements of ultrasonic output power, intensity, and timer accuracy in the clinical operating range were made together with maximum output power and transducer operating frequency. Results of the measurements are presented and the performance characteristics of the units compared with manufacturers' performance criteria for ultrasound therapy devices as given in the Canadian Radiation Emitting Devices (RED) Act.     

镍矿接镍作业生物学监测指标的探讨

本文目的乃在于探讨尿镍或发镍作为生物学监测指标哪个更合适。随机选取某镍矿冶炼车间工人25名为对象,用个体采样器采样测定其接触空气镍的水平,并测定尿镍与发镍含量,调查其接镍作业时间和吸烟与否。用Z-80微机进行了5个变量间的偏相关分析和逐步回归分析。结果表明,尿镍浓度与空气镍接触水平有相关趋势,发镍与目前空气镍接触水平关系不大,尿镍、发镍含量均与接镍作业时间、是否吸烟无明显关系。     

Retention patterns of asbestos fibres in lung tissue among asbestos cement workers.

Retention patterns in lung tissue (determined by transmission electron microscopy and energy dispersive spectrometry) of chrysotile, tremolite, and crocidolite fibres were analysed in 69 dead asbestos cement workers and 96 referents. There was an accumulation of tremolite with time of employment. Among workers who died within three years of the end of exposure, the 13 with high tremolite concentrations had a significantly longer duration of exposure than seven in a low to intermediate category (medians 32 v 20 years; p = 0.018, one sided). Crocidolite showed similar patterns of accumulation. In workers who died more than three years after the end of exposure, there were no correlations between concentrations of amphibole fibres and time between the end of exposure and death. Chrysotile concentrations among workers who died shortly after the end of exposure were higher than among the referents (median difference in concentrations 13 million fibres (f)/g dry weight; p = 0.033, one sided). No quantitative differences in exposure (duration or intensity) could be shown between workers with high and low to intermediate concentrations. Interestingly, all seven workers who had had a high intensity at the end of exposure (> 2.5 f/ml), had low to intermediate chrysotile concentrations at death, whereas those with low exposure were evenly distributed (31 subjects in both concentration categories); hence, there was a dependence between last intensity of exposure and chrysotile concentration (p = 0.014). Among 14 workers with a high average intensity of exposure, both those (n = 5) with high tissue concentrations of chrysotile and those (n = 10) with high tissue concentrations of tremolite fibres had more pronounced fibrosis than those with low to intermediate concentrations (median fibrosis grades for chrysotile: 2 v 1, p = 0.021; for tremolite: 2 v 0.5, p = 0.012). Additionally, workers who died shortly after the end of exposure with high concentrations of chrysotile and crocidolite had smoked more than those with low intermediate concentrations (medians for chrysotile 35 v 15 pack-years, p = 0.030; for crocidolite 37 v 15 pack-years, p = 0.012). The present data indicate that chrysotile has a relatively rapid turnover in human lungs, whereas the amphiboles, tremolite and crocidolite, have a slower turnover. Further, chrysotile retention may be dependent on dose rate. Chrysotile and crocidolite deposition and retention may be increased by tobacco smoking; chrysotile and tremolite by fibrosis.     

Biological indicators of exposure to total and respirable aluminium dust fractions in a primary aluminium smelter.

OBJECTIVES: The study attempts to define biological indicators of aluminium uptake and excretion in workers exposed to airborne aluminium compounds in a primary aluminium smelter. Also, this study defines the total and respirable aluminium dust fractions in two different potrooms, and correlates their concentrations with biological indicators in this group of workers. METHODS: Air was sampled at defined work sites. Non-destructive and conventional techniques were used to find total and respirable aluminium content of the dust. Blood and urine was collected from 84 volunteers employed at various work stations throughout the smelter and from two different cohorts of controls matched for sex, age, and socioeconomic status. Aluminium in serum samples and urine specimens was measured by flameless atomic absorption with a PE 4100 ZL spectrometer. RESULTS: The correlation of aluminium concentrations in serum and urine samples with the degree of exposure was assessed for three arbitrary exposure categories; low (0.036 mg Al/m3), medium (0.35 mg Al/m3) and high (1.47 mg Al/m3) as found in different areas of the smelter. At medium and high exposure, the ratio of respirable to total aluminium in the dust samples varied significantly. At high exposure, serum aluminium, although significantly raised, was still within the normal range of an unexposed population. The workers with low exposure excreted aluminium in urine at levels significantly higher than the controls, but still within the normal range of the population. However, potroom workers with medium and high exposure had significantly higher urinary aluminium than the normal range. CONCLUSIONS: It is concluded that only urinary aluminium constitutes a practical index of occupational exposure at or above 0.35 mg Al/m3, and that the respirable fraction of the dust may play a major role in the biological response to exposure to aluminium in a smelter environment.     

Exposure to airborne nano-titanium dioxide during airless spray painting and sanding

The objectives of the study were to measure and characterize exposure to airborne nanoscale titanium dioxide during airless spraying and sanding of a nano-enabled paint, and to evaluate the effectiveness of dust capture methods in reducing airborne nanoparticle concentrations. A tradesperson performed the work activities in an environmentally controlled chamber. Samples were collected in the tradesperson's breathing zone and in surrounding areas to assess bystander exposure. Filter-based samples were analyzed using gravimetric methods, scanning electron microscopy, and energy dispersive spectroscopy. Differential particle count data were obtained by means of a scanning mobility particle sizer. Local exhaust ventilation provided statistically significant reductions of airborne nanoparticle concentrations during sanding. Sanding the paint after drying with a handheld power sander generated relatively low levels of airborne titanium dioxide. In contrast, task-based exposure measurements collected during the initial airless spray application of the nano-enabled paint suggested a potential for occupational exposures to exceed the time-weighted average exposure limit for ultrafine titanium dioxide recommended by the National Institute for Occupational Safety and Health. Painters applying nano-enabled coatings may have little recourse but to rely, in some instances, on lower tiers of the hierarchy of controls, such as personal protective equipment. In light of these findings, employers and industrial hygienists should characterize exposures and implement the hierarchy of controls to ensure painters are sufficiently protected.     

Evaluation of serum aminoterminal propeptide of type III procollagen as an early marker of the active fibrotic process in asbestos-exposed workers

In an evaluation of the possibility of type III procollagen N-terminal propeptide (PIIINP) being an early marker of the active fibrotic process in asbestos-exposed workers, 91 asbestos workers had higher serum PIIINP concentrations than 108 referents. In 24 workers exposed to low levels of airborne asbestos, the serum PIIINP was higher than in the referents but lower than in an exposed group with higher exposure; furthermore a significant correlation (r = 0.63) was found between serum PIIINP and individual cumulative exposure. These data suggest a dose-effect relationship between asbestos exposure and PIIINP serum concentration. In addition workers with a reduced pulmonary function had higher PIIINP values than the referents or the exposed workers with normal pulmonary function. The serum PIIINP levels were related to asbestos exposure even at low airborne concentrations and may represent an early biological marker of impending fibrotic process induced by asbestos.     

Epidemiological survey among workers exposed to manganese: effects on lung, central nervous system, and some biological indices

A cross-sectional epidemiological study was carried out among 141 male subjects exposed to inorganic manganese (Mn) in a Mn oxide and salt producing plant (mean age 34.3 years; duration of exposure, mean 7.1 years, range 1-19 years). The results were compared with those of a matched control group of 104 subjects. The intensity of Mn exposure was moderate as reflected by the airborne Mn levels and the concentrations of Mn in blood (Mn-B) and in urine (Mn-U). A significantly higher prevalence of cough in cold season, dyspnea during exercise, and recent episodes of acute bronchitis was found in the Mn group. Lung ventilatory parameters (forced vital capacity, FVC; forced expiratory volume in one second, FEV1; peak expiratory flow rate, PEFR) were only mildly altered in the Mn group (smokers) and the intensity and the prevalence of these changes were not related to Mn-B, Mn-U, or duration of exposure. There was no synergistic effect between Mn exposure and smoking on the spirometric parameters. Except for a few nonspecific symptoms (fatigue, tinnitus, trembling of fingers, increased irritability), the prevalence of the other subjective complaints did not differ significantly between the control and Mn groups. Psychomotor tests were more sensitive than the standardized neurological examination for the early detection of adverse effects of Mn on the central nervous system (CNS). Significant alterations were found in simple reaction time (visual), audioverbal short-term memory capacity, and hand tremor (eye-hand coordination, hand steadiness). A slight increase in the number of circulating neutrophils and in the values of several serum parameters (ie, calcium, ceruloplasmin, copper, and ferritin) was also found in the Mn group. There were no clear-cut dose-response relationships between Mn-U or duration of Mn exposure and the prevalence of abnormal CNS or biological findings. The prevalences of disturbances in hand tremor and that of increased levels of serum calcium were related to Mn-B. The response to the eye-hand coordination test suggests the existence of a Mn-B threshold at about 1 microgram Mn/100 ml of whole blood. This study demonstrates that a time-weighted average exposure to airborne Mn dust (total dust) of about 1 mg/m3 for less than 20 years may present preclinical signs of intoxication.     

Effectiveness of High Power Ultrasound for Surimi-Based Preparation of Lionfish (Pterois volitans) Patties by Textural,Sensory and Shape Preference

Lionfish is an invasive and predatory species with low local consumption due to a lack of culinary knowledge of its preparation. A new way to prepare lionfish was proposed to increase variety and provide added value. The aim of this study was to evaluate the effect of high power ultrasound application on the textural properties measured by the texture profile analysis, sensory attributes, and shape preference of surimi patties (rounded and square) made from lionfish. Patties were prepared using lionfish surimi processed with ultrasound (37 kHz; 150 W), sodium citrate (0.3%), sucrose (1%), and salt (2%). Ultrasound exposure increased the hardness of the patties by 35.1%, decreased cohesiveness by 89.7%, and decreased the chewiness by 49.1%. Results show that high power ultrasound showed potential as an environmentally friendly technology to create surimi as a base for patties with sensory and textural appropriateness, increasing the potential culinary applications of lionfish.     

Assessment of variability in biomonitoring data using a large database of biological measures of exposure

Although intra- and interindividual sources of variation in airborne exposures have been extensively studied, similar investigations examining variability in biological measures of exposure have been limited. Following a review of the world's published literature, biological monitoring data were abstracted from 53 studies that examined workers' exposures to metals, solvents, polycyclic aromatic hydrocarbons, and pesticides. Approximately 40% of the studies also reported personal sampling results, which were compiled as well. In this study, the authors evaluated the intra- and interindividual sources of variation in biological measures of exposure collected on workers employed at the same plant. In 60% of the data sets, there was more variation among workers than variation from day to day. Approximately one-fourth of the data were homogeneous with small differences among workers' mean exposure levels. However, an almost equal number of data sets exhibited moderate to extreme levels of heterogeneity in exposures among workers at the same facility. In addition, the relative magnitude of the intra- to interindividual source of variation was larger for biomarkers with short compared to long half-lives, which suggests that biomarkers with half-lives of 7 days or longer exhibit physiologic dampening of fluctuations in external levels of the workplace contaminant and thereby may offer advantages when compared to short-lived biomarkers or exposures assessed by air monitoring. The use of biological indices of exposure, however, places an additional burden on the strategy used to evaluate exposures, because data may be serially correlated as evidenced in this study, which could result in biased estimates of the variance components if autocorrelation is undetected or ignored in the statistical analyses.     

超声功率计的研制

该文介绍了一种由电子天平、目标靶、吸声罩及支撑装置组成的超声功率计的设计与研制。这种超声功率计的电子天平安装在支撑装置上,并使用连杆与目标靶固定连接;通过调节支撑装置可使目标靶悬于超声探头正上方,从而对固定探头的超声功率进行测量。经过对样机的初步测试,其测量稳定且精度较高。