854 resultados para occupational toxicology
Resumo:
The liver fluke Opisthorchis viverrini is classified as a class I carcinogen due to the association between cholangiocarcinoma and chronic O. viverrini infection. During its feeding activity within the bile duct, the parasite secretes several cathepsin F cysteine proteases that may induce or contribute to the pathologies associated with hepatobiliary abnormalities.
Resumo:
The helminth parasite Fasciola hepatica secretes cathepsin L cysteine proteases to invade its host, migrate through tissues and digest haemoglobin, its main source of amino acids. Here we investigated the importance of pH in regulating the activity and functions of the major cathepsin L protease FheCL1. The slightly acidic pH of the parasite gut facilitates the auto-catalytic activation of FheCL1 from its inactive proFheCL1 zymogen; this process was approximately 40-fold faster at pH 4.5 than at pH 7.0. Active mature FheCL1 is very stable at acidic and neutral conditions (the enzyme retained approximately 45% activity when incubated at 37 degrees C and pH 4.5 for 10 days) and displayed a broad pH range for activity peptide substrates and the protein ovalbumin, peaking between pH 5.5 and pH 7.0. This pH profile likely reflects the need for FheCL1 to function both in the parasite gut and in the host tissues. FheCL1, however, could not cleave its natural substrate Hb in the pH range pH 5.5 and pH 7.0; digestion occurred only at pH
Resumo:
Despite concern about the harmful effects of substances contained in various
plastic consumer products, little attention has focused on the more heavily
exposed women working in the plastics industry. Through a review of the
toxicology, industrial hygiene, and epidemiology literatures in conjunction
with qualitative research, this article explores occupational exposures in producing
plastics and health risks to workers, particularly women, who make up
a large part of the workforce. The review demonstrates that workers are
exposed to chemicals that have been identified as mammary carcinogens and
endocrine disrupting chemicals, and that the work environment is heavily
contaminated with dust and fumes. Consequently, plastics workers have a
body burden that far exceeds that found in the general public.
Resumo:
El Hondo is a key area for marbled teal and white-headed duck. We present Pb, Cu, Zn, Se, and As data for bone and liver in birds found dead between 1996 and 2001. Several metals were higher in adult white-headed ducks than in marbled teal. They were higher in female than in male white-headed ducks, and did not differ with sex in marbled teal, but did by age. Lead in liver of adults was influenced by Pb shot ingestion, which was detected in 21% of marbled teal and in 71% of white-headed duck. No marbled teal had liver levels indicative of Pb poisoning, while 86% of white-headed ducks did. Selenium, Zn, and Cu were elevated in 13%, 7%, and 39% of birds, respectively. Whilst Pb shot poses the greatest threat to these species, further work should assess exposure via plants, invertebrates, water, and sediments for other metals, and investigate possible sub-lethal effects.
Resumo:
High levels of As in groundwater commonly found in Bangladesh and other parts of Asia not only pose a risk via drinking water consumption but also a risk in agricultural sustainability and food safety. This review attempts to provide an overview of current knowledge and gaps related to the assessment and management of these risks, including the behaviour of As in the soil-plant system, uptake, phytotoxicity, As speciation in foods, dietary habits, and human health risks. Special emphasis has been given to the situation in Bangladesh, where groundwater via shallow tube wells is the most important source of irrigation water in the dry season. Within the soil-plant system, there is a distinct difference in behaviour of As under flooded conditions, where arsenite (AsIII) predominates, and under nonflooded conditions, where arsenate (AsV) predominates. The former is regarded as most toxic to humans and plants. Limited data indicate that As-contaminated irrigation water can result in a slow buildup of As in the topsoil. In some cases the buildup is reflected by the As levels in crops, in others not. It is not yet possible to predict As uptake and toxicity in plants based on soil parameters. It is unknown under what conditions and in what time frame As is building up in the soil. Representative phytotoxicity data necessary to evaluate current and future soil concentrations are not yet available. Although there are no indications that crop production is currently inhibited by As, long-term risks are clearly present. Therefore, with concurrent assessments of the risks, management options to further prevent As accumulation in the topsoil should already have been explored. With regard to human health, data on As speciation in foods in combination with food consumption data are needed to assess dietary exposure, and these data should include spatial and seasonal variability. It is important to control confounding factors in assessing the risks. In a country where malnutrition is prevalent, levels of inorganic As in foods should be balanced against the nutritional value of the foods. Regarding agriculture, As is only one of the many factors that may pose a risk to the sustainability of crop production. Other risk factors such as nutrient depletion and loss of organic matter also must be taken into account to set priorities in terms of research, management, and overall strategy.
Resumo:
The purpose of this study was to investigate the occupational hazards within the tanning industry caused by contaminated dust. A qualitative assessment of the risk of human exposure to dust was made throughout a commercial Kenyan tannery. Using this information, high-risk points in the processing line were identified and dust sampling regimes developed. An optical set-up using microscopy and digital imaging techniques was used to determine dust particle numbers and size distributions. The results showed that chemical handling was the most hazardous (12 mg m(-3)). A Monte Carlo method was used to estimate the concentration of the dust in the air throughout the tannery during an 8 h working day. This showed that the high-risk area of the tannery was associated with mean concentrations of dust greater than the UK Statutory Instrument 2002 No. 2677. stipulated limits (exceeding 10 mg m(-3) (Inhalable dust limits) and 4 mg m(-3) (Respirable dust limits). This therefore has implications in terms of provision of personal protective equipment (PPE) to the tannery workers for the mitigation of occupational risk.
Resumo:
Fusarium mycotoxins are frequent contaminants of cereals in many world regions, and are suggested risk factors for various acute and chronic human diseases. To date a lack of exposure tools has restricted epidemiological studies of the potential health effects. Recently established exposure biomarkers for deoxynivalenol (DON) and fumonisins are now available and here a pilot biomarker survey of 110 women (aged 39 to 72 years) from Golestan, northern Iran was conducted on samples collected at one time point during August-September 2007. Urinary DON and DON-glucuronide combined were detected frequently (79/110, 72%), mean 1.3 ng DON/ml urine, range not detected (nd)-6.5 ng/ml; mean creatinine adjusted levels were 1.5 ng DON/mg creatinine, range nd-7.1 ng/mg). Neither urinary de-epoxy DON (DOM-1) and DOM-1 glucuronide combined, nor urinary fumonisin B-1 were detected. This study is the first reported biomarker based exposure assessment of DON and fumonisins in this region. Overall DON exposure at this time point appears modest compared to other world regions where data are available.
Resumo:
The aim of this study is to investigate the stress experienced by full-time
maingrade lecturers as a result of changes in college organisation and factors that relate to stress. A questionnaire was constructed to identify possible sources of stress at work and the amount of stress experienced. Two psychometric measures were included—the General Health Questionnaire and the Maslach Burnout Inventory. The former looked at the physiological and psychological effects of stress and the latter, the emotive, cognitive and
behavioural effects, together referred to as 'burnout'. The study sought to investigate stress responses between lecturers employed in colleges that have undergone organisational change compared to those that have not. Two hundred questionnaires and psychometric measures were distributed, by opportunity, to 100 lecturers employed in FE colleges in the north of England and 100 employed in colleges in Northern Ireland. Colleges in the former region had undergone changes in college organisation as a result of incorporation. Colleges in the
latter had not. Incorporation referred to the process whereby colleges became independent of local government control. This led to a series of changes, some of which affected lecturers' terms and conditions. Overall, the indices of reported stress were comparable or markedly greater than earlier research findings, and the trend was for lecturers who had experienced organisational change to report higher measures of stress. GHQ measures showed a significant difference between samples, with the majority of the English sample (69.49%, compared to 40.91%) categorised as 'at risk' of developing symptoms associated with a
transient stress-related disorder, and whilst measures of 'burnout' were more pronounced in the English sample there were no significant differences between samples. In relation to a number of factors, the experience of stress and burnout was more pronounced in the Northern Ireland sample and explanations were offered, such as the influence of cultural variables and the increasing presence of stress-related features in these colleges as they move to incorporation.
Resumo:
Purpose – The purpose of this paper is to consider the occupational stress experienced by chefs and the moderating influence of coping behaviour and locus of control on stress outcomes. Design/methodology/approach – A total of 40 working chefs were surveyed. They were asked to complete an occupational stress questionnaire, the General Health Questionnaire. Differences were
sought between gender and locus of control and stress measures, and correlations were carried out between key variables. Findings – The reported stress was markedly higher than in previous research. Excessive workload,
feeling undervalued and communication issues were common and bullying and threats of violence were present for some. Unexpectedly, locus of control was unable to predict stress experiences. Explanations were offered, such as the possibility that those who perceive they have a strong sense of control may believe that this, paradoxically, affords them the opportunity to engage in unhealthy behaviours. Research limitations/implications – Limitations of the research include the influence of the wider environment, specifically the history of political violence in the province, and its possible effect on stress outcomes. However, this may be negated by the many positive effects peace has brought over the last decade. In drawing conclusions it is important to note the limitations of the sample size and the self-reporting nature of survey responses. Further research could usefully incorporate well-being as well as stress measures, including physiological ones. It would be worth exploring further how one’s sense of control affects perceptions of stress and, in turn, the coping behaviours engaged in. Practical implications – Practical implications include the need for managers and head chefs to provide more feedback to employees, to validate their good work and to foster a supportive working environment. Norms in the working environment endorsing aggressive behaviour must be challenged.
Staff appraisals should consider the need to have work that involves variety and challenge, especially where changes involve increases in workload. Originality/value – This paper identifies some important ingredients to reduce distress and it will be of value to chefs and other kitchen staff and, more broadly, to those involved in people management.
Resumo:
Accurate assessment and treatment of pain and stress in preterm infants in neonatal intensive care units (NICU) is vital because pain and stress responses have been linked to long-term alterations in development in this population.
Resumo:
Host defence peptides (HDPs) are expressed throughout the animal and plant kingdoms. They have multifunctional roles in the defence against infectious agents of mammals, possessing both bactericidal and immune-modulatory activities. We have identified a novel family of molecules secreted by helminth parasites (helminth defence molecules; HDMs) that exhibit similar structural and biochemical characteristics to the HDPs. Here, we have analyzed the functional activities of four HDMs derived from Schistosoma mansoni and Fasciola hepatica and compared them to human, mouse, bovine and sheep HDPs. Unlike the mammalian HDPs the helminth-derived HDMs show no antimicrobial activity and are non-cytotoxic to mammalian cells (macrophages and red blood cells). However, both the mammalian- and helminth-derived peptides suppress the activation of macrophages by microbial stimuli and alter the response of B cells to cytokine stimulation. Therefore, we hypothesise that HDMs represent a novel family of HDPs that evolved to regulate the immune responses of their mammalian hosts by retaining potent immune modulatory properties without causing deleterious cytotoxic effects.