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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, Arsenic and Compounds


Text Only Home | Graphic-Rich Site | Overview | Risk and Causation | Diagnosis | Treatment | Prognosis | Differential Diagnosis | Specialists | Rehabilitation | Comorbid Conditions | Complications | Factors Influencing Duration | Length of Disability | Ability to Work | Failure to Recover | Medical Codes | References

Medical Codes

ICD-9-CM:
985.1 - Toxic Effect of Other Metals, That From All Sources Except Medicinal Substances, Arsenic and Its Compounds

Related Terms

  • Arsenic Poisoning
  • Arsenic Salts
  • Arsenic Trichloride
  • Arsenic Trioxide
  • Metallic Arsenic

Overview

Arsenic is a naturally occurring element in the earth's crust. Pure arsenic, a gray-colored metal, is rarely found in the environment. Instead it is usually combined with one or more other elements such as oxygen, chlorine, and sulfur. This combination is referred to as inorganic arsenic. Arsenic combined with carbon and hydrogen is referred to as organic arsenic. The organic forms are usually less toxic than the inorganic forms. While not usually mined, arsenic is instead recovered as a by-product from the smelting of copper, lead, zinc, and other ores. Metal smelter exhaust can release arsenic into the environment. Also present in coal at variable concentrations, arsenic is released into the environment during combustion. Arsenic near acid or acid mist can release the very deadly gas, arsine. Application of pesticides and herbicides containing arsenic has increased environmental dispersion. Twenty-one arsenic compounds are considered to be of concern because of their toxicity and/or presence in the environment.

Fruits and vegetables are sprayed with arsenicals. It is sometimes added to the feed of poultry and other livestock to promote growth, and concentrations are found in many species of fish and shellfish. The average daily human intake of arsenic in US is about 50 micrograms. Almost all of this is ingested through food in the US. Some ingestion of arsenic also occurs through drinking water.

Currently, 90% of arsenic produced is used as wood preservative. The remainder is primarily used for pesticides or herbicides. Therefore, the major source of occupational exposure to arsenic-containing compounds is from the manufacture of arsenical preservatives, herbicides, and pesticides. Some products, mostly weed killers, use organic arsenic as the active ingredient. Other pesticides use inorganic forms of arsenic to kill plants, insects, or rodents, or to preserve wood. Persons who manufacture or use these pesticides or who handle treated wood may be exposed to arsenic.

Arsenic is also used in metallurgy; in the production of pigments; glass; most computer chips using silicon-based technology; homeopathic formulations; and in the production of some semiconductors used in LEDs, laser, and solar devices.

Arsenic is found in many different chemical states and chemical forms. It can enter the body through the lungs by inhalation, though the skin by direct contact, and through the mouth by ingestion. Inhalation is the most common form of occupational exposure. Ingestion is the most common non-occupational exposure. The health effects of arsenic vary widely depending on the chemical form of the arsenic, the concentration, the route of exposure, and the duration of exposure. For example, all individuals who eat seafood, especially shell fish, are exposed to low levels of organic arsenic. However, this form is benign, and it normally passes through the body and is excreted in the urine without causing health problems. Arsine gas, typically used in the semi-conductor industry, is another form of arsenic. This form of arsenic is highly toxic and causes damage to multiple organ systems. Kidney failure, severe anemia and cardiac arrest are common with arsine gas exposure. Many arsenic compounds are irritants of skin, mucous membranes and eyes. Acute arsenic poisoning is rare and usually is the result of ingestion.

Inorganic arsenic is classified as a human carcinogen. Chronic exposure causes increased rates of skin and lung cancers.

Incidence and Prevalence: True incidence is not known. The estimated number of persons exposed to arsenic is about 900,000 people a day (Dyro).

Source: Medical Disability Advisor



Causation and Known Risk Factors

Industrial exposure (as well as exposure in forestry, agriculture, or construction) is more likely to occur in males, while the environmental, intentional poisoning and accidental exposures affect males and females equally. All races appear to be affected equally. The exposures occur usually in adults. Persons working in certain industries (e.g. copper smelting, mining, or agriculture) are at increased risk of arsenic exposure. Well-water drinking also increases the risk. People living in the areas with high arsenic content (e.g. emissions from industrial plants) are also at increased risk of arsenic exposure (Dyro).

Source: Medical Disability Advisor



Diagnosis

History: Symptoms for inorganic arsenic exposure differ depending on whether the individual is experiencing acute toxicity, subacute toxicity, or chronic toxicity.

In acute toxicity, initial symptoms include burning in the throat and mouth, difficulty swallowing (individual may also report metallic taste), nausea, severe abdominal pain, vomiting and diarrhea. These usually occur within hours after arsenic has been ingested. The acute toxicity may occur through various routes, including absorption of inorganic arsenic, ingestion or inhalation. Individual may also complain of dizziness later on, and may appear acutely confused (delirious). If the toxicity was due to inhalation, the individual may also complain of malaise, headache, weakness, and difficulty breathing.

In subacute toxicity, most symptoms center in the abdominal area, and the affected individuals most frequently experience diarrhea, vomiting, and abdominal pain. Other symptoms include nausea, tingling and/or burning in hands and feet, confusion and overall weakness.

In chronic toxicity, the hallmarks are tingling, burning, weakness and/or pain in hands and feet (peripheral neuropathy) and changes in the skin. Individuals may complain of constipation. There might be impaired cognitive function. If chronic toxicity was secondary to respiratory exposure, the individual may develop hoarseness.

Physical exam: In acute toxicity, liver, kidneys, bone marrow, nervous system and cardiovascular effects may be present. Cardiovascular collapse may occur, as well as the dysfunction of the heart muscle. The individual may experience seizures, and later on go into coma, particularly if there was a large ingestion of arsenic. A brain disorder (encephalopathy) may follow seizures and coma. About 3 weeks after ingestion or earlier, the individual may develop peripheral neuropathy. Some individuals may develop edema under the skin in the legs and eyelids.

In subacute toxicity, peripheral neuropathy is often observed, and in some cases, the heart is affected also. Arrhythmias may occur. The individual may develop anemia and problems with kidneys. Often, Mees' lines may be observed.

In chronic toxicity, skin disorders are characterized by hyperpigmentation, hyperkeratoses, as well as dermatitis of both irritant and allergic types. Brittle nails and Mees' lines may be observed. In chronic toxicity secondary to respiratory exposure, disease of upper respiratory tract and nasal septal perforation could be noted. Anemia might be observed as well. Some organic arsenic compounds (arsanilate) have a selective effect on the optic nerve and can cause blindness. Impaired peripheral circulation and Raynaud's phenomenon have been reported following long term exposure.

Tests: Urinary levels of arsenic can be used as an index of harmful exposure, but dietary factors must be considered before interpreting results. Seafood, especially shellfish, contains significant amounts of organic arsenicals which are nontoxic but affect the total urinary arsenic levels. The biologic half-life of arsenic in urine is 1 to 2 days in individuals with normal renal function, therefore, urine tests are only valuable in evaluating recent arsenic exposures. Measurement of arsenic in hair or fingernails has been used to detect chronic exposure but levels are not reliable. It is recommended to perform a complete blood count test to identify the type of anemia the individual may have, which may indicate whether the individual has had an acute or chronic exposure. If the individual had an acute exposure, it would be useful to do liver function tests and kidney tests, with monitoring of select electrolytes (e.g., potassium, calcium, and magnesium). In acute exposure, the upper GI x-rays may be useful to view the arsenic-containing material that was ingested. Also, MRI and CT scans of the brain may be useful in acute toxicity to visualize edema and/or bleeding in the brain. In some individuals, the electrodiagnostic testing (to assess function of motor and sensory nerves) may be done to monitor how well the treatment is progressing. Sometimes nerve biopsies may be done.

Source: Medical Disability Advisor



Treatment

Treatment must include removal from exposure, decontamination and supportive care. If diagnosis of acute arsenic exposure is confirmed, chemical agents to bind and remove the arsenic (chelation therapy) should be used urgently in conjunction with urine monitoring until arsenic levels in the urine are less than 50 mcg/L. Individuals who have developed renal failure may need to be placed on hemodialysis. With chronic arsenic exposure, individuals should be immediately removed from the contaminating source.

Source: Medical Disability Advisor



Prognosis

Prognosis is dependent on the extent, duration, and severity of exposure, and which compound the individual was exposed to. Rapid absorption of certain arsenic compounds through the skin may lead to fatal outcomes.

Source: Medical Disability Advisor



Differential Diagnosis

Source: Medical Disability Advisor



Specialists

  • Emergency Medicine Physician
  • Family Physician
  • Hematologist
  • Internal Medicine Physician
  • Medical Toxicologist
  • Nephrologist
  • Neurologist
  • Oncologist
  • Pharmacologist
  • Preventive Medicine Specialist
  • Psychiatrist
  • Pulmonologist

Source: Medical Disability Advisor



Rehabilitation

Rehabilitation should include therapy designed to accommodate any physical or neurological impairment associated with high level arsenic exposures. Psychological counseling may be necessary to address lingering mental disorder or deterioration. Physical therapy and rehabilitation may be required long-term for individuals who have developed neurologic complications.

Individual may need to undergo a training program dealing with exposure to arsenic and the necessity for workplace protection.

Source: Medical Disability Advisor



Comorbid Conditions

  • Alcohol abuse
  • Any pre-existing disease
  • Smoking

Source: Medical Disability Advisor



Complications

In multiple studies, occupational and environmental chronic exposure to inorganic arsenic compounds have been causally associated with cancer of the skin and lungs.

Source: Medical Disability Advisor



Factors Influencing Duration

Absorbed dose is the primary determinant of severity of toxic effects, and therefore severity and duration of disability. Absorbed dose is dependent on environmental levels, routes of exposure (skin contact, inhalation, ingestion) and duration of exposure. Other factors influencing duration include age, pregnancy and allergy, all of which affect individual susceptibility to the toxic effect of chemical exposures. Psychological and emotional factors may also play a role in the extent and duration of disability.

Source: Medical Disability Advisor



Ability to Work (Return to Work Considerations)

The Environmental Protection Agency limits the amounts of arsenic released into the environment and used to make pesticides. The maximum contaminant level of drinking water is 10 parts per billion. The Occupational Safety and Health Administration (OSHA) has set the legal airborne exposure limit (PEL) at 0.10 mg/cubic meter averaged over an 8-hour work shift. The National Institute for Safety and Occupational Health (NIOSH) has recommended an airborne exposure limit is 0.002 mg/cubic meter not to be exceeded during any 15-minute work period. The American Conference of Governmental Industrial Hygienists (ACGIH) recommends an airborne exposure limit of 0.01 mg/cubic meter averaged over an 8-hour work shift.

The individual must have access to information about the health effects of arsenic exposure in the workplace. Respirators, air filters, and protective clothing and eyewear may be needed. Length and levels of arsenic exposure in the work place must be monitored.

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:

  • Has the diagnosis of arsenic poisoning been confirmed?
  • Is there a positive history of arsenic exposure in the workplace? If not, does individual live in the an area with a high arsenic content, or uses well-water for drinking?
  • Was this an intentional poisoning with a suicidal attempt?
  • Is the clinical illness, including the history, physical examination, and laboratory findings, consistent with other case descriptions?
  • Are the urine levels of arsenic at or near the normal value?
  • Is the timing between exposure and clinical onset compatible with the known biologic facts about the hazard?
  • Does individual have an underlying condition that may impact recovery?

Regarding treatment:

  • If the diagnosis of arsenic poisoning was confirmed, was individual treated with chelation therapy?
  • If systemic impairment exists, what specific treatments has individual received? Would individual benefit from additional or continued therapy?
  • How soon after exposure was appropriate treatment initiated?

Regarding prognosis:

  • Was the exposure dose within the range of doses believed to cause such effects? Are there special attributes of this particular individual that make it more or less likely that he or she would be so affected?
  • Could arsenic exposure be occurring outside the workplace; i.e., in the home, in the community, or in recreational activities?
  • If this was a suicidal attempt on the part of individual, was he or she referred to a psychiatrist?
  • Has individual recently worked in another organization where arsenic exposure was higher?
  • If occupational duties put individual at risk of exposure, is protective gear provided?
  • Has individual been instructed in its proper use?

Source: Medical Disability Advisor



References

Cited

Dyro, Frances M. "Arsenic." eMedicine. Eds. Jonathan S. Rutchik, et al. 23 May. 2002. Medscape. 8 Oct. 2004 <http://emedicine.com/neuro/topic20.htm>.

Source: Medical Disability Advisor