The bone marrow niche, stem cells, and leukemia: impact of drugs, chemicals, and the environment.

Hematopoietic stem cells (HSCs) are a unique population of somatic stem cells that can both self-renew for long-term reconstitution of HSCs and differentiate into hematopoietic progenitor cells (HPCs), which in turn give rise, in a hierarchical manner, to the entire myeloid and lymphoid lineages. The differentiation and maturation of these lineages occurs in the bone marrow (BM) niche, a microenvironment that regulates self-renewal, survival, differentiation, and proliferation, with interactions among signaling pathways in the HSCs and the niche required to establish and maintain homeostasis. The accumulation of genetic mutations and cytogenetic abnormalities within cells of the partially differentiated myeloid lineage, particularly as a result of exposure to benzene or cytotoxic anticancer drugs, can give rise to malignancies like acute myeloid leukemia and myelodysplastic syndrome. Better understanding of the mechanisms driving these malignancies and susceptibility factors, both within HPCs and cells within the BM niche, may lead to the development of strategies for prevention of occupational and cancer therapy-induced disease.

The bone marrow niche, stem cells, and leukemia: impact of drugs, chemicals, and the environment.

Detection, treatment, and prevention of bone marrow diseases have long been the aims of experimental and clinical hematologists and mechanistically oriented toxicologists. Among these diseases is aplastic anemia, which manifests as the cessation of normal blood cell production; the leukemias, in contrast, feature the production of excessive hematologic cancer cells. Both diseases are associated with exposure to either industrial chemicals or cancer chemotherapeutic agents. Studies of hematopoietic bone marrow cells in culture have shown that the generation of circulating blood cells requires the interaction of hematopoietic stem cells (HSCs) with supporting marrow stromal cells; yet, isolation of HSCs from bone destroys the unique morphology of the marrow stroma in which the HSCs reside. Imaging techniques and related studies have made it possible to examine specific niches where HSCs may either initiate differentiation toward mature blood cells or reside in a dormant state awaiting a signal to begin differentiation. HSCs and related cells may be highly vulnerable to the mutagenic or toxic effects of drugs or other chemicals early in these processes. Additional studies are required to determine the mechanisms by which drug or chemical exposure may affect these cells and lead to either depression of bone marrow function or to leukemia.

Safety management and risk assessment in chemical laboratories.

The present paper highlights a new safety management program, MICE (Management, Information, Control and Emergency), which has been specifically adapted for the academic environment. The process starts with an exhaustive hazard inventory supported by a platform assembling specific hazards encountered in laboratories and their subsequent classification. A proof of concept is given by a series of implementations in the domain of chemistry targeting workplace health protection. The methodology is expressed through three examples to illustrate how the MICE program can be used to address safety concerns regarding chemicals, strong magnetic fields and nanoparticles in research laboratories. A comprehensive chemical management program is also depicted.

Stabilization of residues obtained from the treatment of laboratory waste. Part 1--Treatment path of metals in a plasma melting system.

The objective of this study is to investigate the treatment path of metals during the plasma vitrification of fly ash, bottom ash, sludge, and activated carbon collected from a laboratory waste treatment plant. Sampling, digestion, and analysis procedures that followed the standard methods of the Taiwan Environmental Protection Administration were used to determine the composition of the input and output materials. The microstructure was qualitatively examined using a scanning electron microscope. The results show that the vitrification process successfully vitrified the toxic input materials into a stable, glassy, amorphous slag. During vitrification, metals with low boiling points (As, Cd, Hg, Pb, and Zn) were vaporized into the flue gas. Metals with high boiling points and high specific weights went into the ingot, and the residual metals remained in the molten materials as the slag. The distribution of metals shows their behavior during vitrification and can provide a reference for vitrifying hazardous materials.

Biossegurança e biosseguridade do manuseio do xilol em laboratórios de anatomia patológica / Biosecurity and biosafety of xilol handling in anatomical pathology laboratories

O conceito de biosseguridade e biossegurança vem sendo cada vez mais difundido e valorizado à medida que o entendimento da responsabilidade do profissional, envolvido em atividades que manipulam agentes biológicos, químicos, físicos e radioativos, não se limita somente às ações de prevenção de riscos derivados de sua atividade específica, mas também de todas as pessoas que, diretamente ou indiretamente, participam dessa atividade. Nos laboratórios de anatomia patológica é muito importante que os profissionais entendam a distinção entre esses dois termos e os ponham em prática para maior segurança. O objetivo deste trabalho foi fazer uma revisão dos efeitos do xilol, uma das principais substâncias voláteis usadas diariamente em um laboratório de anatomia patológica, e suas implicações nos profissionais envolvidos, decorrentes da falta de conhecimento ou prática da biosseguridadee biossegurança. Foi observado, de forma geral, que as legislações existentes em vigor em nosso país são pouco específicas para os laboratórios que trabalham com anatomia patológica (biopsias e citologia). Quando o enfoque é biossegurança, além dos cuidados normais de boas práticas de laboratório, são necessários procedimentos específicos para minimizar os riscos de acidentes pessoais e de contaminação ambiental. Cabe ao nosso país implementar medidas cabíveis para os profissionais que lidam com histotecnologia, oferecendo a estes o reconhecimento legal, por meio de cursos de qualificação aos técnicos. Da mesma forma, cabe a todos os gestores envolvidos na área da saúde orientar seus profissionais quanto à conscientização da prática diária de todos os aspectos envolvidos com a biosseguridade e biossegurança.

Biosafety and biosecurity concepts have been increasingly used and valued, considering that the understanding of the responsibility of the professional involved in activities that manipulate biological, chemical, physical and radioactive agents, is not only limited to risk prevention measures originated from his or her specific activity, but also from all persons who directly or indirectly participate in these activities. In anatomical pathology laboratories, it is very important for professionals to understand the difference between these two terms and to put them into practice to achieve a higher level of security. The objective of this study was to perform a review of xylol effects, which is one of the main volatile substances daily used in anatomical pathology laboratories, and its implications for the professionals involved, due to the lack of knowledge or biosafety and biosecurity practices. Generally speaking, it was observed that current laws in our country are not very specific for anatomical pathology laboratories, which perform biopsies and cytology. When the focus is biosecurity, in addition to the normal care of good laboratory practices, specific procedures to minimize the risks of personal accident and environmental contamination are necessary. The implementation of suitable measures for the professional dealing with histotechnology is our country's responsibility, by offering them legal acknowledgement of the profession through qualification courses for technicians. Similarly, all managers involved in the health sector must instruct their professionals with regard to the awareness of the daily practice of all aspects involved with biosafety and biosecurity.

Laboratory work and adverse pregnancy outcomes.

BACKGROUND: Laboratory workers are commonly exposed to chemical, biological and physical agents. They also may adopt poor postures for long periods and be engaged in moving and handling. These factors may increase the risk of adverse pregnancy outcome in female laboratory workers. AIMS: To assess whether laboratory work during pregnancy increases the risk of adverse pregnancy outcomes. METHODS: The 1990-2006 Finnish Medical Birth Registry was used to identify all singleton newborns of all Finnish laboratory workers (n = 5425) and those of teachers (n = 21,438) as the reference population. The main outcomes were sexual differentiation (female gender), low birth weight, high birth weight, preterm delivery, post-term delivery, small-for-gestational age (SGA), large-for-gestational age and perinatal death. The generalized estimating equation (GEE) analysis was used to estimate odds ratios (ORs) adjusted for maternal age, parity, marital status and maternal smoking during pregnancy. RESULTS: In the GEE analysis, the risk of low birth weight (adjusted OR: 1.27, 95% CI: 1.08-1.45) and SGA (adjusted OR: 1.27, 95% CI: 1.02-1.52) was higher in laboratory workers than in teachers. Correspondingly the prevalence of high birth weight (> or = 4000 g) was lower in newborns of laboratory workers (adjusted OR: 0.90, 95% CI: 0.83-0.98). The prevalence of post-term deliveries was close to being significantly higher among newborns of laboratory workers (adjusted OR: 1.16, 95% CI: 1.00-1.31). CONCLUSIONS: This large population-based study provides evidence that laboratory work may be associated with reduced foetal growth.

[LaboRisCh: an algorithm for assessment of health risks due to chemicals in research laboratories and similar workplaces]. / LaboRisCh: un algoritmo per la valutazione dei rischi per la salute da agenti chimici nei laboratori di ricerca e negli ambienti di lavoro affini.

BACKGROUND: Chemical risk assessment in research laboratories is complicated by factors such as the large number of agents to be considered, each present in small quantities, and the very short and erratic periods of exposure, all of which make reliable environmental and biological monitoring particularly difficult and at times impossible. In such environments, a preliminary evaluation procedure based on algorithms would be useful to establish the hazard potential of a given situation and to guide the appropriate intervention. OBJECTIVES: The LaboRisCh model was expressly designed to assess the health risk due to chemicals in research laboratories and similar workplaces. METHODS: The model is based on the calculation of the value of a synthetic single risk index for each substance and compound found in a laboratory and, subsequently, of a further synthetic single risk index for the whole laboratory or, where required, a section thereof. This makes LaboRisCh a compromise between need for information, ease of use, and resources required for the assessment. The risk index includes several items, chiefly the physical and chemical properties, intrinsic hazard potential, amount, dilution, and time of exposure to each agent; waste management; possible interactions; presence and efficiency of collective and individual protection devices, and staff training in good laboratory practices. The value of the synthetic single index corresponds to one of three areas: no risk (green), possible risk (yellow), and certain risk (red). CONCLUSIONS: Preliminary data confirm the model. LaboRisCh appears to be a reliable method for chemical risk assessment in research laboratories and similar workplaces.

Anaphylaxis and allergic contact urticaria from occupational airborne exposure to HBTU.

We describe a case of anaphylaxis and allergic contact urticaria from occupational airborne exposure to HBTU (o-(benzotriazol-1-yl)-N,N,N',N'-tetramethyluronium hexafluorophosphate), which is a chemical used widely for solid and solution-phase peptide synthesis. Previously, the use of this chemical has been associated with occupational asthma, allergic contact urticaria and allergic contact dermatitis in individual cases, but not with anaphylaxis. Our diagnoses were based on the clinical symptoms, positive skin prick test (SPT) and positive skin provocation test to HBTU. The positive SPT indicates that the anaphylaxis reaction was IgE-mediated. We recommend that in the handling of HBTU, appropriate safety measures should be compulsory, and if work-related symptoms develop, the possibility of anaphylaxis should be considered in advising on appropriate work tasks.

Safety in the histochemistry laboratory.

Histochemistry and histopathology laboratories are extremely dangerous workplaces owing to the abundance of chemical hazards that constitute major safety and health concerns. A brief review is presented of some of the hazards to which laboratory personnel are exposed. These include fixatives, solvents, embedding media, dyes and stains, and histochemical substrates. Laboratory staff should be fully informed of the dangers and potential long-term health hazards and take the necessary precautionary measures. Despite the abundance of chemical hazards in the histochemistry laboratory, the overall number of work accidents and injuries remains low.