Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Job Classification

In most duration tables, five job classifications are displayed. These job classifications are based on the amount of physical effort required to perform the work. The classifications correspond to the Strength Factor classifications described in the United States Department of Labor's Dictionary of Occupational Titles. The following definitions are quoted directly from that publication.

Sedentary Work Exerting up to 10 pounds (4.5 kg) of force occasionally and/or a negligible amount of force frequently or constantly to lift, carry, push, pull, or otherwise move objects, including the human body. Sedentary work involves sitting most of the time, but may involve walking or standing for brief periods of time. Jobs are sedentary if walking and standing are required only occasionally and other sedentary criteria are met.

Light Work Exerting up to 20 pounds (9.1 kg) of force occasionally and/or up to 10 pounds (4.5 kg) of force frequently, and/or negligible amount of force constantly to move objects. Physical demand requirements are in excess of those for Sedentary Work. Light Work usually requires walking or standing to a significant degree. However, if the use of the arm and/or leg controls requires exertion of forces greater than that for Sedentary Work and the worker sits most the time, the job is rated Light Work.

Medium Work Exerting up to 50 (22.7 kg) pounds of force occasionally, and/or up to 25 pounds (11.3 kg) of force frequently, and/or up to 10 pounds (4.5 kg) of forces constantly to move objects.

Heavy Work Exerting up to 100 pounds (45.4 kg) of force occasionally, and/or up to 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Very Heavy Work Exerting in excess of 100 pounds (45.4 kg) of force occasionally, and/or in excess of 50 pounds (22.7 kg) of force frequently, and/or in excess of 20 pounds (9.1 kg) of force constantly to move objects.

Toxic Effects, Methyl Alcohol


Related Terms

  • Carbinol Poisoning
  • Colombian Spirits Poisoning
  • Colonial Spirit Poisoning
  • Methyl Alcohol Poisoning
  • Methyl Hydroxide Poisoning
  • Monohydroxymethane Poisoning
  • Pyroxylic Spirit Poisoning
  • Wood Alcohol Poisoning
  • Wood Naphtha Poisoning
  • Wood Spirits Poisoning

Differential Diagnosis

Specialists

  • Medical Toxicologist
  • Pharmacologist
  • Preventive Medicine Specialist

Comorbid Conditions

  • Kidney disease
  • Liver disease
  • Pulmonary insufficiency

Factors Influencing Duration

The severity and duration of methanol exposure, method of exposure, immediacy of treatment, the individual's response to exposure, and the effectiveness of treatment influence the length of disability. Age and the general state of health, an individual's job requirements, any complications, and pre-existing disease will affect disability.

Medical Codes

ICD-9-CM:
980.1 - Toxic Effects, Methyl Alcohol

Overview

Methanol is a clear, colorless liquid with a pungent odor at normal temperatures. First discovered in the late 1600s, methanol has been called wood alcohol because it was obtained commercially from the destructive distillation of wood for more than a century. True wood alcohol contained more contaminants, including acetone and acetic acid, than the chemical-grade methanol available today.

For many years, the largest use for methanol (about 50% of the total produced) was in the production of formaldehyde. It is now also used in the production of acetic acid, methyl tert-butyl ether (MTBE), oxindol (used to improve gasoline octane), and other chemical intermediates. Methanol is also a solvent found in paint remover, varnish, and shellac. Methanol is extremely toxic: as little as 2 to 8 ounces can be fatal to an adult. Workers in industries where methyl alcohol is used and produced may be exposed to harmful levels via inhalation or skin contact. Historically, methanol poisoning has occurred primarily from intentional ingestion as a substitute for alcoholic beverages or as a contaminant of "moonshine." Two products containing methanol that are most often ingested are antifreeze solutions and windshield washer products.

Incidence and Prevalence: One thousand forty-nine people were exposed to methanol in 2002 according to the American Association of Poison Control Centers. Thirty-two people had a life-threatening reaction to the exposure and experienced medical complications. Thirteen people died (Watson).

Source: Medical Disability Advisor



Diagnosis

History: The most significant toxic effects of methanol are optic nerve damage, metabolic acidosis and respiratory depression. Typically within 18 to 48 hours after ingestion, individuals develop nausea, abdominal pain, headache, and slowed breathing. This is accompanied by visual disturbances such as blurred or double vision, changes in color perception, constricted visual fields and complete blindness.

Physical exam: Individuals may experience vision problems, including difficulty seeing clearly, and changes in their field of vision leading to eventual blindness. Individuals may also be fatigued, confused and in a stupor or coma. The abdomen may be tender when palpated, and the individual may experience seizures, cranial nerve palsy, shortness of breath, low blood pressure, slow heart rate, and decreased respirations.

Tests: Individuals need to have a methanol level, serum osmolality, serum electrolytes, serum amylase or lipase, and complete blood count to rule out low blood sugar, pancreatitis and anemia. An arterial blood gas (ABG) can be helpful in establishing metabolic acidosis. MRI and CT scan can help rule out any neurological injury.

Source: Medical Disability Advisor



Treatment

The first step in therapy is to remove the individual from further exposure. Further treatment depends on the route and extent of exposure and the organ system affected. If ingestion has occurred less than 1 hour before presentation, the stomach should be pumped (gastric lavage).

In the event of skin contact, the affected skin is immediately flooded with water and washed with soap and water. In case of eye contact, the individual should first be checked for contact lenses and any, if present, should be removed. The eye is then promptly irrigated with copious amounts of water for 20 to 30 minutes.

In all cases of potentially severe poisoning, treatment should include hydration, correction of acidosis and administration of folate to increase the oxidation of formic acid. Whenever plasma methanol concentrations or ingested doses are higher than 20 mg/dL, or when there is evidence of acidosis or visual abnormalities, ethanol is administered intravenously. Hemodialysis is indicated when plasma methanol concentrations are greater than 50 mg/dL, metabolic acidosis is unresponsive to bicarbonate given intravenously, the kidneys have failed, or the patient has blindness or vision difficulty.

Source: Medical Disability Advisor



Prognosis

Prognosis is dependent on the extent and duration of exposure.

Source: Medical Disability Advisor



Rehabilitation

Any toxic condition caused by methyl alcohol may warrant rehabilitation if the condition results in general weakness and/or affects the respiratory system. Once initial symptoms are stabilized and a physician determines no contraindications to physical activity, a gradual strengthening program is initiated by the rehabilitation professional.

If necessary, respiratory exercises may be instructed to improve ventilation for the individual with breathing difficulties. Muscles that aid in breathing are strengthened by several techniques, which may include instructing the individual to assume relaxed sitting postures, and strengthening secondary respiratory muscles.

Once breathing returns to normal, individuals rehabilitating from this toxic condition progress to strengthening and endurance exercises with aerobic-type activities that increase the individual's ability to work and helps them resist fatigue. As endurance continues to increase without symptoms of shortness of breath, the individual may begin active upper and lower extremity exercises with progressive resistance using free weights and/or weight machines. Frequency of the program may vary somewhat depending on the individual's general health. If tolerated, strengthening exercises are performed 3 times a week with aerobic activities on the non-strengthening days of the program.

Muscle weakness is addressed by strengthening exercises along with education regarding the importance of remaining as active as possible with enjoyable activities. If exercises are tolerated well, resistance is then added to each exercise to build strength in order to return to work/functional activities. If necessary, the rehabilitation program also addresses any neurological complications such as loss of balance and coordination.

Occupational and speech therapy become involved in the rehabilitation process to help the individual cope with other neurological deficits that are causing difficulty with communication and activities of daily living. Psychological counseling may also be needed during the rehabilitation period and during long-term medical therapy.

Several disciplines of rehabilitation for an indefinite period may be necessary if significant impaired motor functions are present. The rehabilitation program varies for individuals affected by the toxic effects of methyl alcohol. The intensity and progression of exercises depends on the individual's overall health and the body organs affected, specifically the respiratory system.

Source: Medical Disability Advisor



Complications

Formic acid is a metabolic product of methanol and can cause a severe increase in acidity (acidosis), visual disturbances leading to blindness, and death. Other complications include muscle spasms, disorders of movement and parkinsonian symptoms or extra pyramidal symptoms (EPS).

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

Recognized exposure limits for methanol include the following: The Occupational Safety and Health Administration's (OSHA) legal airborne permissible exposure limit (PEL) is 200 parts per million (ppm) methanol averaged over an 8-hour work shift.

The National Institute of Occupational Safety and Health's (NIOSH) recommended airborne exposure limit is 200 ppm methanol averaged over a 10-hour work shift, not to exceed 800 ppm methanol during any 15-minute work period.

The American Conference of Governmental Industrial Hygienists' (ACGIH) recommended airborne exposure limit is 200 ppm methanol averaged over an 8-hour work shift, not to exceed 250 ppm methanol as a short-term exposure limit (STEL).

Source: Medical Disability Advisor



Failure to Recover

If an individual fails to recover within the expected maximum duration period, the reader may wish to consider the following questions to better understand the specifics of an individual's medical case.

Regarding diagnosis:

  • Are the whole blood and urine levels of methanol and/or its metabolites at or near the normal value?
  • Is the clinical illness including the history, physical examination, and laboratory findings consistent with other case descriptions?
  • Is there a positive history of methanol exposure in the workplace?
  • Has individual recently worked in another organization where methyl alcohol exposure is higher?
  • Could methanol exposure be occurring outside the workplace, for example, in the home, community, or recreational activities?

Regarding treatment:

  • Has individual been removed completely from further exposure?
  • If ingestion occurred less than 1 hour before presentation, did individual undergo stomaching pumping (gastric lavage)?
  • If skin contact occurred, was affected skin immediately flooded with water and washed with soap and water?
  • If eye contact occurred, was the eye promptly irrigated with copious amounts of water for at least 20 to 30 minutes?
  • If toxicity was severe, did individual receive intravenous hydration, correction of acidosis, and administration of folate?
  • Was kidney dialysis (hemodialysis) required?
  • Did treatment successfully resolve all symptoms?

Regarding prognosis:

  • Is the timing between exposure and clinical onset compatible with the known biologic facts about the hazard?
  • Is the exposure dose within the range of doses believed to cause such effects?
  • Are there special attributes of the particular individual that make it more or less likely that he or she would be so affected?
  • Are there additional lifestyle or behavioral factors that may potentially contribute to this condition?
  • Where there remains significant uncertainty about the cause, how important is it to be certain?

Source: Medical Disability Advisor



References

Cited

Watson, William A., et al. "2002 Annual Report of the American Association of Poison Control Centers Toxic Exposure Surveillance System." American Journal of Emergency Medicine 21 5 (2003): 353-421. MD Consult. Elsevier, Inc. 4 Jan. 2005 <http://home.mdconsult.com>.

Source: Medical Disability Advisor






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