TCE
PCE
C2H3Cl
CH2=CHCONH2
HCHO
100
This is one of the most important chlorinated solvents. Its main applications have been as a dry-cleaning agent and a metal degreaser.
What is trichloroethylene.
===
It is a colorless, volatile liquid with a boiling
point of 87°C. Trichloroethylene was thought to be much less toxic than carbon tetrachloride and was used, to a large extent, to replace CCl4 in many industrial processes.
100
This chemical is used in the textile industry for dry cleaning, processing, and finishing.
What is perchloroethylene.
===
More than 70% of all dry-cleaning operations in the United States use PCE. Another important use is in metal cleaning and degreasing. PCE is also a raw
material for the synthesis of fluorocarbons.
100
This chemical is used primarily in the production of plastic piping and conduit.
What is polyvinyl chloride.
===
It is also used in making floor coverings, home furnishings, electrical applications, recreational products (records, toys), packaging (film, sheet, and bottles), and transportation materials (automobile tops, upholstery, and mats).
100
The major use of this monomer is in the production of polymers, which are used for waste and water treatment flocculants, in products for sewage dewatering, and in a variety of products for the water treatment industry.
What is acrylamide.
===
Other uses include strengtheners for papermaking and retention aids, drilling-mud additives, textile treatment, and surface coatings. One of the more important uses is as a grouting agent, particularly in mining and tunnel construction.
100
This is known to physicians as a tissue preservative and disinfectant; its largest use is the manufacture of its urea-form and polyacetal and phenolic resins.
What is formaldehyde.
===
Formaldehyde is used in relatively small quantities for preservation and disinfection.
Other important uses include wood industry products, molding compounds, foundry resins, adhesives for insulation, slow-release fertilizers, manufacture of permanent-press finishes of cellulose fabrics, and formaldehyde-based textile finishes.
200
Trichloroethylene is absorbed rapidly through this route, and only a relatively small fraction of the amount inhaled is eliminated unchanged in the exhaled air.
What is the respiratory route.
===
The metabolic transformation of trichloroethylene has been shown to proceed through formation of a complex with cytochrome P-450.
NIOSH has estimated that 3.5 million workers in the United States are occupationally exposed to trichloroethylene; about 100,000 are exposed full time.
200
High blood levels of PCE can cause an alteration in calcium dynamics, causing this type of effect in young adults.
What is arrhythmogenic effect.
===
Premature ventricular contractions are frequently seen with high blood levels and disappears
completely after removal from exposure.
200
This is the chief route of exposure to vinyl chloride monomer (VCM).
What is respiratory.
===
Primarily through inhalation of the gas, although dermal absorption may be significant during manual reactor-vessel cleaning.
200
The characteristic toxic neuropathy has a distal to proximal evolution and progression occurs with involvement of more proximal segments known as this.
What is “stocking and glove” distribution.
===
The earliest and most severe changes are
in the distal segments of the lower and upper extremities.
Signs indicating CNS involvement are somnolence, vertigo, ataxic gait, and occasionally slight organic mental syndrome. EEG abnormalities have also been described.
200
Formaldehyde vapor exposure causes direct irritation of the skin and respiratory tract. Both direct irritation (eczematous reaction) and this type of hypersensitivity occurs.
What is allergic contact dermatitis (type IV delayed hypersensitivity).
===
After a few days of exposure to formaldehyde solutions or formaldehyde-containing resins, the individual may develop a sudden urticarial eczematous reaction of the skin of the eyelids, face, neck, and flexor surfaces of the arms.
Direct irritation of the eyes, nose, and throat occurs among most people exposed to 0.1–3 ppm of formaldehyde vapor.
300
The urinary excretion of these metabolites can
be used for biologic monitoring of trichloroethylene exposure.
What are trichloroacetic acid and trichloroethanol.
===
Trichloroethanol excretion reaches its peak 24 hours after exposure, while trichloroacetic acid reaches its highest urinary level 3 days after exposure.
300
True or False. The metabolism of PCE generates compounds associated with hepatic toxicity and carcinogenicity, along with generation of reactive metabolites that produce renal toxicity carcinogenicity.
What is True.
===
For biological monitoring of exposure
to PCE, measurements of urinary trichloroacetic acid (slow) and blood levels of PCE can be used. A blood level of 1 mg/L found 16 hours after exposure corresponds to a TWA exposure of less than 50 ppm.
Concentrations of PCE in exhaled air may prove useful after recent exposure.
300
Chronic toxicity from VCM exposure can result in this syndrome where skin changes are similar to scleroderma, with involvement of the finger and hands.
What is Raynaud's syndrome.
===
Acroosteolysis - symptoms of Raynaud phenomenon, osteolysis in the terminal phalanges of some of the fingers, and thickening or raised nodules on the hands and forearms.
Acroosteolysis appears to be irreversible after cessation of exposure.
Vinyl chloride disease is a syndrome consisting of Raynaud phenomenon, acroosteolysis, joint and muscle pain, enhanced collagen deposition, stiffness of the hands, and scleroderma-like skin changes.
300
True or False. Motor nerve action potentials usually are reduced and are the most sensitive electrophysiologic test.
What is False.
===
Sensory nerve conduction velocities have been found to be more affected than motor nerve conduction velocities.
Recovery after cessation of exposure is slow; it may take several months to 2 years.
300
This type of asthma has been reported as a result of exposure to formaldehyde resin dust.
What is occupational asthma.
===
Workers exposed to formaldehyde have significant reduction in forced expiratory volume in 1 second (FEV1) and significantly lower respiratory symptoms than do unexposed controls. However, the rate of decline of lung function in formaldehyde-exposed workers is not greater than expected.
400
True or False. Hepatotoxicity and nephrotoxicity of trichloroethylene are much higher than those of carbon tetrachloride.
What is False.
===
Trichloroethylene can enhance the hepatotoxicity of carbon tetrachloride, possibly potentiating lipid peroxidation.
400
Perchloroethylene is a probable human carcinogen (IARC group 2A), with the strongest epidemiologic evidence pointing towards these type of cancers.
*IARC = International Agency for Research on Cancer
What are esophageal and bladder cancer.
===
NIOSH has designated PCE as a carcinogen and has recommended that occupational exposure be limited to the lowest feasible limit. In 1986, the
ACGIH recommended a TLV-TWA of 50 ppm.
*ACGIH = American Conference of Governmental Industrial Hygienists
400
This type of hypertension has been the prominent feature in some cases of nonmalignant vinyl chloride liver disease; esophageal varices and bleeding have occurred.
What is portal hypertension.
===
Fatty degenerative changes in the hepatocytes and focal necrosis have sometimes been observed and are thought to be more pronounced in cases studied shortly after cessation of toxic exposure.
400
Along with PPE, a open/closed system process is important to minimize exposure.
What is closed.
===
Some examples of a closed system process are: mechanized bag loading of polymerization reactors and closed-line transfer of liquid acrylamide.
400
Occupationally exposed persons are at risk of developing this type of cancer.
What is nasopharyngeal and hypopharyngeal cancer.
===
There are also several studies showing an increased risk of sinonasal cancer (particularly adenocarcinoma).
500
Reducing exposure to TCE can be practiced in the occupational workspace but also in this supply source.
What is water supply source.
===
TCE has been found in at least 460 of 1179 hazardous waste sites on the National Priorities List. Federal and state surveys have shown up to 34% of water supply sources in the United States are contaminated with TCE.
500
This alternative to perc is used in dry cleaning.
What is liquid carbon dioxide.
===
Although CO2 avoids the toxic risks of perc, CO2 does not clean some forms of grime as well.
The environmental impact is very low and is almost entirely nontoxic. It does not persist in clothing or in the environment, and its greenhouse gas potential is lower than that of many organic solvents.
500
This should be available and are required when exposure levels exceed VC limits.
What is air-supplied respirator.
===
The federal standard for exposure to vinyl chloride is 1 ppm for an 8-hour period; the ceiling of 5 ppm should never be exceeded for more than 15 minutes.
500
True or False. Symptoms of peripheral neuropathy is a sensitive indicator of early neurotoxicity caused by acrylamide exposure.
What is False.
===
Vibration threshold is most sensitive indicator out of the components of the neurotoxicity index.
Hemoglobin adducts of acrylamide are significantly correlated with a “neurotoxicity index” based on
signs and symptoms of peripheral neuropathy, vibration thresholds, and electroneuromyography measurements.
500
Name some prevention work practice strategies.
What are as follows:
1) Ventilation engineering controls
2) Safety goggles
3) Full-facepiece respirator with organic vapor cartridge (at air concentrations above PEL)
4) Protective neoprene clothing and boots and gloves impervious to formaldehyde should be worn to prevent skin contact.