Electrospun nanofibers: solving global issues. Mater Today. New electropositive filter for concentrating enteroviruses and noroviruses from large volumes of water.
Desalination by biomimetic aquaporin membranes: review of status and prospects. An aquaporin-based vesicle-embedded polymeric membrane for low energy water filtration. J Mater Chem A. Espinoza LA. Heterogeneous photocatalysis with titanium dioxide suspensions containing bromide and dissolved organic carbon. TiO 2 for water treatment: parameters affecting the kinetics and mechanisms of photocatalysis. Appl Catal B Environ. Recent developments in photocatalytic water treatment technology: a review.
TiO2 photocatalysis and related surface phenomena. Surf Sci Rep. Heterogeneous photocatalytic degradation of organic contaminants over titanium dioxide: a review of funda mentals, process and problems. J Photochem Photobiol A Chem. Nanoscale Res Lett. Photocatalytic water treatment by titanium dioxide: recent updates. A new combination of a membrane and a photcatalytic reactor for the depollution of turbid water.
Ollis DF. Integrating photocatalysis and membrane technologies for water treatment. Ann N Y Acad Sci. Keuter V. Development of multi-barrier systems consisting of nano-enhanced membranes and UV-LEDs for water purification applications. September 23—27, Membrane Technology. Horizon Work Programme — Leadership in enabling and industrial technologies. Climate action, environment, resource efficiency and raw materials.
Ecotoxicology of Nano-TiO 2 — an evaluation of its toxicity to organisms of aquatic ecosystems. Int J Environ Res. Toxicity of various silver nanoparticles compared with silver ions in Daphnia magna. J Nanobiotechnology. Potential release pathways, environmental fate, and ecological risks of carbon nanotubes.
Bioaccumulation and ecotoxicity of carbon nanotubes. Chem Cent J. Nanomaterial case studies: nanoscale titanium dioxide in water treatment and in topical sunscreen. Hund-Rinke K, Simon M. Ecotoxic effect of photocatalytic active nano particles TiO2 on algae and daphnids.
Environ Sci Pollut Res Int. Effects of particle composition and species on toxicity of metallic nano-materials in aquatic organisms. Environ Toxicol Chem. Aquatic eco-toxicity tests of some nanomaterials.
Development of a base set of toxicity tests using ultrafine TiO 2 particles as a component of nanoparticle risk management. Toxicol Lett. Lovern SB, Klaper R. Daphnia magna mortality when exposed to titanium dioxide and fullerene C60 nanoparticles. Characterization and in vivo ecotoxicity evaluation of double-wall carbon nanotubes in larvae of the amphibian Xenopus laevis. Aquat Toxicol. Effects of silver and cerium dioxide micro- and nano-sized particles on Daphnia magna.
J Environ Monit. In vivo evaluation of carbon fullerene toxicity using embryonic zebrafish. Toxicity and bioaccumulation of TiO 2 nanopar-ticle aggregates in Daphnia magna.
Toxicity assessment of manufactured nanomaterials using the unicellular green alga Chlamydomonas reinhardtii. Ecotoxicity of CdTe quantum dots to freshwater mussels: impacts on immune system, oxidative stress and genotoxicity.
Exposure of sticklebacks Gasterosteus aculeatus to cadmium sulfide nanoparticles: biological effects and the importance of experimental design. Mar Environ Res. Ecotoxicity of nanoparticles of CuO and ZnO in natural water. Environ Pollut. Toxicity of single walled carbon nano-tubes to rainbow trout, Oncorhynchus mykiss : respiratory toxicity, organ pathologies, and other physiological effects. Toxicity bio-marker expression in daphnids exposed to manufactured nanoparticles: changes in toxicity with functionalization.
Toxicity of an engineered nanoparticle fullerene, C 60 in two aquatic species, Daphnia and fathead minnow. C 60 fullerene: a powerful antioxidant or a damaging agent? The importance of an in-depth material characterization prior to toxicity assays. C60 in water: nanocrystal formation and microbial response.
Toxicity and bioaccumulation of xenobiotic organic compounds in the presence of aqueous suspensions of nano-C Effects of aqueous stable fullerene nanocrystals nC 60 an Daphnia magna : evaluation of sub-lethal reproductive responses and accumulation. Nowack B, Bucheli T. Occurrence, behavior and effects of nanoparticles in the environment.
The behavior of silver nanotextiles during washing. Neglible particle-specific antibacterial activity of silver nanoparticles. Nano Lett. Appl Phys A. Nanotoxicology: an emerging discipline evolving from studies of ultrafine particles. Environ Health Perspect. Report for the ICCR. Insight into serum protein interactions with functionalized magnetic nanoparticles in biological media. Environmental Protection Agency.
Characterization and properties of metallic iron nanoparticles: spectroscopy, electrochemistry and kinetics. European Chemicals Bureau. Technical Guidance Document on Risk Assessment.
European Protection Agency Office of Research. Nanomaterial case study: nanoscale silver in disinfectant spray. Hyung H, Kim JH. Dispersion of C 60 in natural water and removal by conventional drinking water processes. Support Center Support Center. External link. Please review our privacy policy. Point-of-use, removal of organics, heavy metals, bacteria. Removal of heavy metals arsenic and radionuclides, media filters, slurry reactors, powders, pellets.
Highly assessable sorption sides, bactericidal, reusable. Point-of-use, heavily degradable contaminants pharmaceuticals, antibiotics. Ultralong carbon nanotubes with extremely high specific salt adsorption. Bifunctional inner shell adsorbs organics, outer branches adsorb heavy metals , reusable. Biodegradable, biocompatible, nontoxic bioadsorbent combination of chitosan and dendrites. Controlled release of nanosilver, bactericidal.
Reduced active surface through immobilization of nanosilver particles. Bactericidal, low human toxicity Nano-TiO 2 : high chemical stability, very long life time. Nanosilver, limited durability Nano-TiO 2 , requires ultraviolet activation.
Point-of-use water disinfection, antibiofouling surfaces, decontamination of organic compounds, remote areas. TiO 2 modification for activation by visible light, TiO 2 nanotubes. Stabilization is required surface modification. Groundwater remediation chlorinated hydrocarbon, perchlorates.
Entrapment in polymeric matrices for stabilization. Charge-based repulsion, relative low pressure, high selectivity. Membrane blocking concentration polarization. Reduction of hardness, color, odor, heavy metals. Resistant bulk material required when using oxidizing nanomaterial, possibly release of nanoparticles.
Highly dependent on type of composite, eg, reverse osmosis, removal of micropollutants. High porosity, tailor-made, higher permeate efficiency, bactericidal.
Composite nanofiber membranes, bionanofiber membranes. Stabilization processes surface imprinting, embedding in polymers. Algae green algae, Desmodesmus subpicatus TiO 2 : Invertebrates Daphnia pulex and Ceriodaphnia dubia Fish zebrafish, Danio rerio Algae green algae, Pseudokirchneriella subcapita 5. Algae green algae, P. Fish rainbow trout, Oncorhynchus mykiss 6.
Invertebrate Daphnia magna 7. LC 50 5. Frog larvae Xenopus laevis 8. Field Studies Effort. Nanotechnology Resources. Guidance and Publications.
Partnerships and Collaborations. Links with this icon indicate that you are leaving the CDC website. Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
You will be subject to the destination website's privacy policy when you follow the link. CDC is not responsible for Section compliance accessibility on other federal or private website. Note the change in terminology from MSDS. SDSs must contain a minimum of 16 elements:. As with current MSDSs, these sheets are intended to inform employers and personnel of the hazards associated with the chemicals they are handling, and to act as a resource for management of the chemicals.
Trained personnel should evaluate the information and use it to develop safety and emergency response policies, protocols, and procedures that are tailored to the workplace or laboratory.
As discussed above, although MSDSs are invaluable resources, they suffer some limitations as applied to risk assessment in the specific context of the laboratory. As indicated in their name, LCSSs provide information on chemicals in the context of laboratory use.
These documents are summaries and are not intended to be comprehensive or to fulfill the needs of all conceivable users of a chemical. In conjunction with the guidelines described in this chapter, the LCSS gives essential information required to assess the risks associated with the use of a particular chemical in the laboratory. Included in an LCSS are the key physical, chemical, and toxicological data necessary to evaluate the relative degree of hazard posed by a substance.
LCSSs also contain a concise critical discussion, presented in a style readily understandable to trained laboratory personnel, of the toxicity, flammability, reactivity, and explosivity of the chemical; recommendations for the handling, storage, and disposal of the title substance; and first-aid and emergency response procedures.
Several criteria were used in selecting these chemicals, the most important consideration being whether the substance is commonly used in laboratories.
Preference was also given to materials that pose relatively serious hazards. Finally, an effort was made to select chemicals representing a variety of classes of substances, so as to provide models for the future development of additional LCSSs.
A blank copy of the form is provided for development of laboratory-specific LCSSs. Commercial suppliers are required by law OSHA Hazard Communication Standard to provide their chemicals in containers with precautionary labels. Labels usually present concise and nontechnical summaries of the principal hazards associated with their contents.
However, labels serve as valuable reminders of the key hazards associated with the substance. As with the MSDS, the quality of information presented on a label can be inconsistent. Additionally, labeling is not always required for chemicals transferred between laboratories within the same building. The resources described above provide the foundation for risk assessment of chemicals in the laboratory.
This section highlights the sources that should be consulted for additional information on specific harmful effects of chemical substances. Although MSDSs and LCSSs include information on toxic effects, in some situations laboratory personnel should seek additional more detailed information. This step is particularly important when laboratory personnel are planning to use chemicals that have a high degree of acute or chronic toxicity or when it is anticipated that work will be conducted with a particular toxic substance frequently or over an extended period of time.
Institutional CHPs include the requirement for CHOs, who are capable of providing information on hazards and controls. CHOs can assist laboratory personnel in obtaining and interpreting hazard information and in ensuring the availability of training and information for all laboratory personnel. The following annotated list provides references on the hazardous properties of chemicals and which are useful for assessing risks in the laboratory. A number of Web-based resources also exist. These and other such databases are accessible through various online computer data services; also, most of this information is available as CD and computer updates.
Many of these services can be accessed for up-to-date toxicity information. The databases supplied by NLM are easy to use and free to access via the Web. TOXLINE, for example, is an online database that accesses journals and other resources for current toxicological information on drugs and chemicals.
It covers data published from to the present. Free text searching is available on most of the databases. Searching procedures for CAS depend on the various services supplying the database.
Telephone numbers for the above suppliers are as follows:. Additional information can be found on the CAS Web site, www. Specialized databases also exist. This database provides information on toxicity of chemicals to aquatic life, terrestrial plants, and wildlife. Searching any database listed above is best done using the CAS registry number for the particular chemical.
One important source of information for laboratory personnel is training sessions, and the critical place it holds in creating a safe environment should not be underestimated. Facts are only as useful as one's ability to interpret and apply them to a given problem, and training provides context for their use. Hands-on, scenario-based training is ideal because it provides the participants with the chance to practice activities and behaviors in a safe way. Such training is especially useful for learning emergency response procedures.
Another effective tool, particularly when trying to build awareness of a given safety concern, is case studies. Prior to beginning any laboratory activity, it is important to ensure that personnel have enough training to safely perform required tasks.
If new equipment, materials, or techniques are to be used, a risk assessment should be performed, and any knowledge gaps should be filled before beginning work. More information about training programs can be found in Chapter 2 , section 2. The chemicals encountered in the laboratory have a broad spectrum of physical, chemical, and toxicological properties and physiological effects. The risks associated with chemicals must be well understood prior to their use in an experiment.
The risk of toxic effects is related to both the extent of exposure and the inherent toxicity of a chemical. As discussed in detail below, extent of exposure is determined by the dose, the duration and frequency of exposure, and the route of exposure. Exposure to even large doses of chemicals with little inherent toxicity, such as phosphate buffer, presents low risk. In contrast, even small quantities of chemicals with high inherent toxicity or corrosivity may cause significant adverse effects.
The duration and frequency of exposure are also critical factors in determining whether a chemical will produce harmful effects. A single exposure to some chemicals is sufficient to produce an adverse health effect; for other chemicals repeated exposure is required to produce toxic effects.
For most substances, the route of exposure through the skin, the eyes, the gastrointestinal tract, or the respiratory tract is also an important consideration in risk assessment. For chemicals that are systemic toxicants, the internal dose to the target organ is a critical factor. Exposure to acute toxicants can be guided by well-defined toxicity parameters based on animal studies and often human exposure from accidental poisoning.
The analogous quantitative data needed to make decisions about the neurotoxicity and immunogenicity of various chemicals is often unavailable. When considering possible toxicity hazards while planning an experiment, recognizing that the combination of the toxic effects of two substances may be significantly greater than the toxic effect of either substance alone is important.
Because most chemical reactions produce mixtures of substances with combined toxicities that have never been evaluated, it is prudent to assume that mixtures of different substances i. Furthermore, chemical reactions involving two or more substances may form reaction products that are significantly more toxic than the starting reactants.
This possibility of generating toxic reaction products may not be anticipated by trained laboratory personnel in cases where the reactants are mixed unintentionally. For example, inadvertent mixing of formaldehyde a common tissue fixative and hydrogen chloride results in the generation of bis chloromethyl ether, a potent human carcinogen.
All laboratory personnel must understand certain basic principles of toxicology and recognize the major classes of toxic and corrosive chemicals. The next sections of this chapter summarize the key concepts involved in assessing the risks associated with the use of toxic chemicals in the laboratory. Also see Chapter 6 , section 6. Box 4. The following outline provides a summary of the steps discussed in this chapter that trained laboratory personnel should use to assess the risks of handling toxic chemicals.
Note that if a laboratory more Toxicology is the study of the adverse effects of chemicals on living systems. The basic tenets of toxicology are that no substance is entirely safe and that all chemicals result in some toxic effects if a high enough amount dose of the substance comes in contact with a living system.
As mentioned in Chapter 2 , Paracelsus noted that the dose makes the poison and is perhaps the most important concept for all trained laboratory personnel to know. For example, water, a vital substance for life, results in death if a sufficiently large amount i. On the other hand, sodium cyanide, a highly lethal chemical, produces no permanent acute effects if a living system is exposed to a sufficiently low dose.
The single most important factor that determines whether a substance is harmful or, conversely, safe to an individual is the relationship between the amount and concentration of the chemical reaching the target organ, and the toxic effect it produces. For all chemicals, there is a range of concentrations that result in a graded effect between the extremes of no effect and death. In toxicology, this range is referred to as the dose-response relationship for the chemical. The dose is the amount of the chemical and the response is the effect of the chemical.
This relationship is unique for each chemical, although for similar types of chemicals, the dose-response relationships are often similar. See Figure 4. Among the thousands of laboratory chemicals, a wide spectrum of doses exists that are required to produce toxic effects and even death.
For most chemicals, a threshold dose has been established by rule or by consensus below which a chemical is not considered to be harmful to most individuals. In these curves, dosage is plotted against the percent of the population affected by the dosage.
Curve A represents a compound that has an effect on some percent of the population even at small doses. Curve B represents a compound that has an effect only above a dosage threshold.
Some chemicals e. Other substances, however, have no harmful effects following doses in excess of several grams. One way to evaluate the acute toxicity i. The LD 50 is usually expressed in milligrams or grams per kilogram of body weight.
For volatile chemicals i. The LC 50 is given in parts per million, milligrams per liter, or milligrams per cubic meter. In general, the larger the LD 50 or LC 50 , the more chemical it takes to kill the test animals and, therefore, the lower the toxicity of the chemical. Although lethal dose values may vary among animal species and between animals and humans, chemicals that are highly toxic to animals are generally highly toxic to humans.
Toxic effects of chemicals occur after single acute , intermittent repeated , or long-term repeated chronic exposure. An acutely toxic substance causes damage as the result of a single short-duration exposure. Hydrogen cyanide, hydrogen sulfide, and nitrogen dioxide are examples of acute toxins. In contrast, a chronically toxic substance causes damage after repeated or long-duration exposure or causes damage that becomes evident only after a long latency period.
Chronic toxins include all carcinogens, reproductive toxins, and certain heavy metals and their compounds. Many chronic toxins are extremely dangerous because of their long latency periods: the cumulative effect of low exposures to such substances may not become apparent for many years. Many chemicals may be hazardous both acutely and chronically depending on exposure level and duration.
In a general sense, the longer the duration of exposure, that is, the longer the body or tissues in the body is in contact with a chemical, the greater the opportunity for toxic effects to occur.
Frequency of exposure also has an important influence on the nature and extent of toxicity. The total amount of a chemical required to produce a toxic effect is generally less for a single exposure than for intermittent or repeated exposures because many chemicals are eliminated from the body over time, because injuries are often repaired, and because tissues may adapt in response to repeated low-dose exposures.
Some toxic effects occur only after long-term exposure because sufficient amounts of chemical cannot be attained in the tissue by a single exposure. Sometimes a chemical has to be present in a tissue for a considerable time to produce injury.
For example, the neurotoxic and carcinogenic effects from exposure to heavy metals usually require long-term, repeated exposure. The time between exposure to a chemical and onset of toxic effects varies depending on the chemical and the exposure.
For example, the toxic effects of carbon monoxide, sodium cyanide, and carbon disulfide are evident within minutes. The chemical reaches the target organ rapidly and the organ responds rapidly. For many chemicals, the toxic effect is most severe between one and a few days after exposure.
However, some chemicals produce delayed toxicity; in fact, the neurotoxicity produced by some chemicals is not observed until a few weeks after exposure. Delayed toxic effects are produced by chemical carcinogens and some organ toxins that produce progressive diseases such as pulmonary fibrosis and emphysema: in humans, it usually takes 10 to 30 years between exposure to a known human carcinogen and the detection of a tumor, and pulmonary fibrosis may take 10 or more years to result in symptoms.
Exposure to chemicals in the laboratory occurs by several routes: 1 inhalation, 2 contact with skin or eyes, 3 ingestion, and 4 injection. Important features of these different pathways are detailed below. Toxic materials that enter the body via inhalation include gases, the vapors of volatile liquids, mists and sprays of both volatile and nonvolatile liquid substances, and solid chemicals in the form of particles, fibers, and dusts.
Inhalation of toxic gases and vapors produces poisoning by absorption through the mucous membranes of the mouth, throat, and lungs and also damages these tissues seriously by local action. Inhaled gases and vapors pass into the capillaries of the lungs and are carried into the circulatory system, where absorption is extremely rapid.
Because of the large surface area of the lungs in humans approximately 75 m 2 , they are the main site for absorption of many toxic materials. The factors governing the absorption of gases and vapors from the respiratory tract differ significantly from those that govern the absorption of particulate substances. Factors controlling the absorption of inhaled gases and vapors include the solubility of the gas in body fluids and the reactivity of the gas with tissues and the fluid lining the respiratory tract.
Gases or vapors that are highly water soluble, such as methanol, acetone, hydrogen chloride, and ammonia, dissolve predominantly in the lining of the nose and windpipe trachea and therefore tend to be absorbed from those regions. These sites of absorption are also potential sites of toxicity. Formaldehyde is an example of a reactive highly water-soluble vapor for which the nose is a major site of deposition.
In contrast to water-soluble gases, reactive gases with low water solubility, such as ozone, phosgene, and nitrogen dioxide, penetrate farther into the respiratory tract and thus come into contact with the smaller tubes of the airways. Gases and vapors that are not water soluble but are more fat soluble, such as benzene, methylene chloride, and trichloroethylene, are not completely removed by interaction with the surfaces of the nose, trachea, and small airways.
As a result, these gases penetrate the airways down into the deep lung, where they can diffuse across the thin alveoli lung tissue into the blood. The more soluble a gas is in the blood, the more it will be dissolved and transported to other organs. For inhaled solid chemicals, an important factor in determining if and where a particle will be deposited in the respiratory tract is its size. Thus, depending on the size of an inhaled particle, it will be deposited in different sections of the respiratory tract, and the location affects the local toxicity and the absorption of the material.
In general, particles that are water soluble dissolve within minutes or days, and chemicals that are not water soluble but have a moderate degree of fat solubility also clear rapidly into the blood. Those that are not water soluble or highly fat soluble do not dissolve and are retained in the lungs for long periods of time. Metal oxides, asbestos, fiberglass, and silica are examples of water-insoluble inorganic particles that are retained in the lungs for years.
A number of factors affect the airborne concentrations of chemicals, but vapor pressure the tendency of molecules to escape from the liquid or solid phase into the gaseous phase is the most important characteristic.
The higher the vapor pressure is, the greater the potential concentration of the chemical in the air. Fortunately, the ventilation system in most laboratories prevents an equilibrium concentration from developing in the breathing zone of laboratory personnel.
Even very low vapor pressure chemicals are dangerous if the material is highly toxic. A classic example is elemental mercury. Although the vapor pressure of mercury at room temperature is only 0. The TLV for mercury is 0.
The vapor pressure of a chemical increases with temperature; therefore, heating solvents or reaction mixtures increases the potential for high airborne concentrations. Also, a spilled volatile chemical evaporates very quickly because of its large surface area, creating a significant exposure potential.
Clearly, careful handling of volatile chemicals is very important; keeping containers tightly closed or covered and using volatiles in laboratory chemical hoods help avoid unnecessary exposure to inhaled chemicals. Certain types of particulate materials also present potential for airborne exposure.
If a material has a very low density or a very small particle size, it tends to remain airborne for a considerable time. For example, the very fine dust cloud generated by emptying a low-density particulate e. Such operations should therefore be carried out in a laboratory chemical hood or in a glovebox.
Operations that generate aerosols suspensions of microscopic droplets in air , such as vigorous boiling, high-speed blending, or bubbling gas through a liquid, increase the potential for exposure via inhalation. Consequently, these and other such operations on toxic chemicals should also be carried out in a laboratory chemical hood.
Chemical contact with the skin is a frequent mode of injury in the laboratory. Many chemicals injure the skin directly by causing skin irritation and allergic skin reactions. Corrosive chemicals cause severe burns. In addition to causing local toxic effects, many chemicals are absorbed through the skin in sufficient quantity to produce systemic toxicity. The main avenues by which chemicals enter the body through the skin are the hair follicles, sebaceous glands, sweat glands, and cuts or abrasions of the outer layer.
Absorption of chemicals through the skin depends on a number of factors, including chemical concentration, chemical reactivity, and the solubility of the chemical in fat and water.
Absorption is also dependent on the condition of the skin, the part of the body exposed, and duration of contact. Differences in skin structure affect the degree to which chemicals are absorbed. In general, toxicants cross membranes and thin skin e. Although an acid burn on the skin is felt immediately, an alkaline burn takes time to be felt and its damage goes deeper than the acid.
When skin is damaged, penetration of chemicals increases. Acids and alkalis injure the skin and increase its permeability. Burns and skin diseases are the most common examples of skin damage that increase penetration. Also, hydrated skin absorbs chemicals better than dehydrated skin.
Some chemicals such as dimethyl sulfoxide actually increase the penetration of other chemicals through the skin by increasing its permeability. Contact of chemicals with the eyes is of particular concern because the eyes are sensitive to irritants. Few substances are innocuous in contact with the eyes; most are painful and irritating, and a considerable number are capable of causing burns and loss of vision. Alkaline materials, phenols, and acids are particularly corrosive and can cause permanent loss of vision.
Because the eyes contain many blood vessels, they also are a route for the rapid absorption of many chemicals. Many of the chemicals used in the laboratory are extremely hazardous if they enter the mouth and are swallowed. The gastrointestinal tract, which consists of the mouth, esophagus, stomach, and small and large intestines, can be thought of as a tube of variable diameter approximately 5 m long with a large surface area approximately m 2 for absorption.
Toxicants that enter the gastrointestinal tract must be absorbed into the blood to produce a systemic injury, although some chemicals are caustic or irritating to the gastrointestinal tract tissue itself.
Absorption of toxicants takes place along the entire gastrointestinal tract, even in the mouth, and depends on many factors, including the physical properties of the chemical and the speed at which it dissolves.
Absorption increases with surface area, permeability, and residence time in various segments of the tract. Some chemicals increase intestinal permeability and thus increase the rate of absorption.
More chemical will be absorbed if the chemical remains in the intestine for a long time. If a chemical is in a relatively insoluble solid form, it will have limited contact with gastrointestinal tissue, and its rate of absorption will be low.
If it is an organic acid or base, it will be absorbed in that part of the gastrointestinal tract where it is most fat soluble. Fat-soluble chemicals are absorbed more rapidly and extensively than water-soluble chemicals. Exposure to toxic chemicals by injection does not occur frequently in the laboratory, but it occurs inadvertently through mechanical injury from sharp objects such as glass or metal contaminated with chemicals or syringes used for handling chemicals.
The intravenous route of administration is especially dangerous because it introduces the toxicant directly into the bloodstream, eliminating the process of absorption. Nonlaboratory personnel, such as custodial workers or waste handlers, must be protected from exposure by placing sharp objects in special trash containers and not ordinary scrap baskets.
Hypodermic needles with blunt ends are available for laboratory use. Exposure to a harmful chemical results in local toxic effects, systemic toxic effects, or both. Local effects involve injury at the site of first contact; the eyes, the skin, the nose and lungs, and the digestive tract are typical sites of local reactions.
Examples of local effects include 1 inhalation of hazardous materials causing toxic effects in the nose and lungs; 2 contact with harmful materials on the skin or eyes leading to effects ranging from mild irritation to severe tissue damage; and 3 ingestion of caustic substances causing burns and ulcers in the mouth, esophagus, stomach, and intestines.
Systemic effects, by contrast, occur after the toxicant has been absorbed from the site of contact into the bloodstream and distributed throughout the body. Some chemicals produce adverse effects on all tissues of the body, but others tend to selectively injure a particular tissue or organ without affecting others.
The affected organ e. Hundreds of systemic toxic effects of chemicals are known; they result from single acute exposures or from repeated or long-duration chronic exposures that become evident only after a long latency period. Toxic effects are classified as either reversible or irreversible. Reversible toxicity is possible when tissues have the capacity to repair toxic damage, and the damage disappears after cessation of exposure.
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