摘要:

Chlorophenoxy herbicides are used widely for the control of broad-leaved weeds. They exhibit a variety of mechanisms of toxicity including dose-dependent cell membrane damage, uncoupling of oxidative phosphorylation and disruption of acetylcoenzyme A metabolism. Following ingestion, vomiting, abdominal pain, diarrhoea and, occasionally, gastrointestinal haemorrhage are early effects. Hypotension, which is common, is due predominantly to intravascular volume loss, although vasodilation and direct myocardial toxicity may also contribute. Coma, hypertonia, hyperreflexia, ataxia, nystagmus, miosis, hallucinations, convulsions, fasciculation and paralysis may then ensue. Hypoventilation is commonly secondary to CNS depression, but respiratory muscle weakness is a factor in the development of respiratory failure in some patients. Myopathic symptoms including limb muscle weakness, loss of tendon reflexes, myotonia and increased creatine kinase activity have been observed. Metabolic acidosis, rhabdomyolysis, renal failure, increased aminotransferase activities, pyrexia and hyperventilation have been reported. Substantial dermal exposure to 2,4-dichlorophenoxy acetic acid (2,4-D) has led occasionally to systemic features including mild gastrointestinal irritation and progressive mixed sensorimotor peripheral neuropathy. Mild, transient gastrointestinal and peripheral neuromuscular symptoms have occurred after occupational inhalation exposure.In addition to supportive care, urine alkalinization with high-flow urine output will enhance herbicide elimination and should be considered in all seriously poisoned patients. Haemodialysis produces similar herbicide clearances to urine alkalinization without the need for urine pH manipulation and the administration of substantial amounts of intravenous fluid in an already compromised patient.

ISSN:1176-2551    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

Inhalation of a range of agents can result in airway inflammation and/or irritation. This may result in occupational asthma or reactive airways dysfunction syndrome. Reactive airways dysfunction syndrome follows a single large exposure to a chemical agent but is now frequently embraced under the wider term of irritant-induced asthma, a term that also includes asthma due to persistent, lower dose irritant exposures.Bronchial hyperresponsiveness is a hallmark of both occupational asthma and reactive airways dysfunction syndrome, although some patients with occupational asthma may occasionally have typical clinical features without increased bronchial hyperresponsiveness. Following removal of the causal agent in occupational asthma, bronchial hyperresponsiveness generally returns towards normal over a 2-year period, although some individuals demonstrate increased bronchial hyperresponsiveness for longer. Measurement of specific bronchial hyperresponsiveness to the primary causal agent in occupational asthma is used diagnostically but not for assessing prognosis.Bronchial hyperresponsiveness to inhaled methacholine can be measured across individual workshifts to assess work-related change. It may also be measured at the end of a work period when exposure has occurred, and compared with values following a period away from work. There have been no direct, systematic comparisons of changes in methacholine responsiveness in the diagnosis of occupational asthma compared with the more frequently used serial peak flow measurements. Patients with reactive airways dysfunction syndrome classically exhibit non-specific bronchial hyperresponsiveness, which can be readily measured by evaluating responses to inhaled methacholine. Bronchial hyperresponsiveness in reactive airways dysfunction syndrome can persist for many years after initial exposure and serial changes can be used to assess recovery and subsequent disability over time.

ISSN:1176-2551    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

Glaucopsia is a transient disturbance of vision that results from the development of corneal epithelial oedema and associated microcysts produced by exposure to the vapour of certain industrial chemicals, notably aliphatic, alicyclic and heterocyclic amines. After a latent period of a few hours of exposure, there is typically a blurring of vision, objects take on a blue-grey appearance and halos develop around bright objects. Corneal changes can be seen on biomicroscopy and corneal thickness increase is measurable by pachymetry. At concentrations higher than threshold values, visual acuity may be decreased, but contrast sensitivity is a better measure of visual effects. On vacating the causative vapour, vision returns to normal in a few hours without leaving permanent ocular sequelae. Vapour concentration of the causative amine is a major factor in the development of glaucopsia, and a concentration-effect relationship is usually evident. A correlation exists between the vapour concentration, degree of corneal oedema, corneal thickness and subjective symptoms, which  permits  no-effect and threshold-effect concentrations to be determined. The disturbance of vision is a nuisance factor and this may impair work efficiency, predispose to physical accidents and hinder the performance of coordinated tasks (e.g. driving). As a consequence, development of glaucopsia is considered a hazard and is thus an important consideration in assessing workplace safety. From a knowledge of threshold and no-effect concentrations, a workplace permissible vapour exposure concentration can be developed along with industrial hygiene precautionary measures.

ISSN:1176-2551    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

This review assesses the evidence regarding the effects of occupational exposure to organic solvents on colour discrimination and investigates exposure-response relationships and reversibility. This review also considers the current state of knowledge of the possible mechanisms underlying changes in colour vision, and the human health significance of any reported changes.Among the commonly used organic solvents, styrene has been investigated the most thoroughly. Studies of styrene-exposed workers in Germany, Italy and Japan provide a sufficiently consistent body of evidence to support a robust conclusion that styrene does cause an impairment of colour discrimination relative to age-matched controls. Generally, the impairment of colour discrimination observed in styrene-exposed workers tends to be of the tritan (blue-yellow) type, although some cases of red-green impairment have also been found. The limited information available on exposure-response relationships indicates that the effects on colour discrimination would not be expected at 8-hour time weighted average (8h TWA) exposures <20 ppm, although a precise threshold cannot be determined. The data on reversibility are limited and inconclusive. The results from the most rigorous study in which this aspect was investigated point to a reversibility of effects after a 4-week exposure-free period, whereas results from a study with limitations suggest a persistence of effect.The effects of toluene, tetrachloroethylene or mixed solvent exposure have also been investigated, although the information available is generally less reliable than for styrene. For toluene, it can be confidently concluded that this solvent does not have an acute effect on colour discrimination, even when exposures are relatively high (50–150 ppm 8h TWA, and 290–360 ppm 30 minutes TWA). However, studies are inconclusive on whether long-term or repeated exposure to toluene can cause a persistent impairment of colour discrimination.There are few studies that have specifically investigated the effects of tetrachloroethylene on colour discrimination. Among these studies, none has examined the potential for any acute effects of this solvent vapour. A large-scale study in Japanese workers showed no effects of long-term exposure to tetrachloroethylene concentrations in the region of 12–13 ppm. However, the test methodology used was relatively insensitive to changes in colour discrimination, hence the results do not provide reassurance for an absence of subtle effects. A study in Italian dry-cleaners suggested a slight impairment of colour discrimination relative to controls, associated with relatively low exposures to tetrachloroethylene (mean 8h TWA exposure ~6 ppm).The studies concerning the effects of mixed solvent exposure on colour discrimination are based on workers exposed to solvents in paints and lacquers, workers from the printing and petrochemical industries, people working in or living near to microelectronics factories and children exposed to solvents prenatally. However, these studies are subject to design limitations or methodological irregularities, such that no conclusions regarding the effects of mixed solvent exposure on colour discrimination can be drawn. Overall, the only credible evidence for an effect of solvents on colour discrimination derives from the studies on styrene. Because of limitations in the data for other solvents it is not possible to determine whether the evidence for styrene reflects a generic property of solvents.The mechanisms of styrene-induced effects on colour discrimination have not been properly investigated and can only be the subject of speculation. One conclusion that can be drawn is that pathological changes to the ocular system, such as changes to the lens, are unlikely to be involved. This is because there is an absence of convincing evidence for such changes from medical examinations conducted in epidemiological studies of solvent-exposed workers. Also, it seems unlikely that effects on colour discrimination are a nonspecific consequence of more generalised CNS depression, given that styrene-induced effects on colour discrimination appear to occur below the threshold for narcotic effects. The effects of styrene on colour discrimination are subtle and involve an impairment of the ability to discriminate accurately between closely related shades of the same colour rather than ‘colour blindness’. There is no valid basis for using colour discrimination as a marker for other forms of solvent-induced neurotoxicity.

ISSN:1176-2551    

出版商:ADIS    

年代:2004

数据来源: ADIS

摘要:

Latex allergy continues to be an important occupational health problem as latex products are used increasingly worldwide, particularly in healthcare. Although there are few epidemiological studies on the incidence of latex allergy, there has been an increase in the number of case reports over the last 10 years and, based on skin-prick tests, estimates of prevalence of latex allergy in healthcare workers range from 2% to 17%. The allergic health effects arise either from the latex proteins, generally causing a type I immediate hypersensitivity reaction, or from the chemicals added to latex during processing, causing a type IV delayed hypersensitivity reaction. Clinical manifestations of latex allergy depend on the route of exposure and occur by direct contact either with skin or mucosa, or by inhalation. The diagnosis of latex allergy is based on the history, skin tests, serological tests and challenge tests. Thirteen latex allergens have been identified and isolated so far from natural rubber latex. They differ in their potential to elicit immunological responses in individuals allergic to latex and thus have been designated as major or minor allergens. In latex gloves, cornstarch powder used as a donning agent carries latex proteins, thereby increasing inhalational and mucosal exposure to latex proteins. There also appears to be a positive correlation between protein content and allergenicity of gloves. The use of powder-free, low-protein gloves is effective in reducing symptoms and markers of sensitisation. Alternatives to latex gloves, such as nitrile or vinyl gloves are available but may be inferior in respect to manual dexterity and biological impermeability.

ISSN:1176-2551    

出版商:ADIS    

年代:2004

数据来源: ADIS