Methylene Chloride (1910.1052)

1910.1052 App B - Medical Surveillance for Methylene Chloride | Occupational Safety and Health Administration

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1910.1052 App B - Medical Surveillance for Methylene Chloride

Part Number:

1910

Part Number
Title:

Occupational Safety and Health Standards

Subpart:

1910 Subpart Z

Subpart Title:

Toxic and Hazardous Substances

Standard
Number:

1910.1052 App B

Title:

Medical Surveillance for Methylene Chloride

GPO Source:

e-CFR

Appendix B to Section 1910.1052 - Medical Surveillance for Methylene Chloride
I. Primary Route of Entry
Inhalation.
II. Toxicology
Methylene Chloride (MC) is primarily an inhalation hazard. The principal acute hazardous effects
are the depressant action on the central nervous system, possible cardiac toxicity and possible
liver toxicity. The range of CNS effects are from decreased eye/hand coordination and decreased
performance in vigilance tasks to narcosis and even death of individuals exposed at very high
doses. Cardiac toxicity is due to the metabolism of MC to carbon monoxide, and the effects of
carbon monoxide on heart tissue. Carbon monoxide displaces oxygen in the blood, decreases the
oxygen available to heart tissue, increasing the risk of damage to the heart, which may result in
heart attacks in susceptible individuals. Susceptible individuals include persons with heart disease
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and those with risk factors for heart disease.
Elevated liver enzymes and irritation to the respiratory passages and eyes have also been
reported for both humans and experimental animals exposed to MC vapors.
MC is metabolized to carbon monoxide and carbon dioxide via two separate pathways. Through
the first pathway, MC is metabolized to carbon monoxide as an end-product via the P-450 mixed
function oxidase pathway located in the microsomal fraction of the cell. This biotransformation of
MC to carbon monoxide occurs through the process of microsomal oxidative dechlorination which
takes place primarily in the liver. The amount of conversion to carbon monoxide is significant as
measured by the concentration of carboxyhemoglobin, up to 12% measured in the blood following
occupational exposure of up to 610 ppm. Through the second pathway, MC is metabolized to
carbon dioxide as an end product (with formaldehyde and formic acid as metabolic intermediates)
via the glutathione dependent enzyme found in the cytosolic fraction of the liver cell. Metabolites
along this pathway are believed to be associated with the carcinogenic activity of MC.
MC has been tested for carcinogenicity in several laboratory rodents. These rodent studies
indicate that there is clear evidence that MC is carcinogenic to male and female mice and female
rats. Based on epidemiologic studies, OSHA has concluded that there is suggestive evidence of
increased cancer risk in MC-related worker populations. The epidemiological evidence is
consistent with the finding of excess cancer in the experimental animal studies. NIOSH regards
MC as a potential occupational carcinogen and the International Agency for Research Cancer
(IARC) classifies MC as an animal carcinogen. OSHA considers MC as a suspected human
carcinogen.
III. Medical Signs and Symptoms of Acute Exposure
Skin exposure to liquid MC may cause irritation or skin burns. Liquid MC can also be irritating to
the eyes. MC is also absorbed through the skin and may contribute to the MC exposure by
inhalation.
At high concentrations in air, MC may cause nausea, vomiting, light-headedness, numbness of
the extremities, changes in blood enzyme levels, and breathing problems, leading to bronchitis
and pulmonary edema, unconsciousness and even death.
At lower concentrations in air, MC may cause irritation to the skin, eye, and respiratory tract and
occasionally headache and nausea. Perhaps the greatest problem from exposure to low
concentrations of MC is the CNS effects on coordination and alertness that may cause unsafe
operations of machinery and equipment, leading to self-injury or accidents.
Low levels and short duration exposures do not seem to produce permanent disability, but chronic

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exposures to MC have been demonstrated to produce liver toxicity in animals, and therefore, the
evidence is suggestive for liver toxicity in humans after chronic exposure.
Chronic exposure to MC may also cause cancer.
IV. Surveillance and Preventive Considerations
As discussed in sections II and III of this appendix, MC is classified as a suspect or potential
human carcinogen. It is a central nervous system (CNS) depressant and a skin, eye and
respiratory tract irritant. At extremely high concentrations, MC has caused liver damage in
animals. MC principally affects the CNS, where it acts as a narcotic. The observation of the
symptoms characteristic of CNS depression, along with a physical examination, provides the best
detection of early neurological disorders. Since exposure to MC also increases the
carboxyhemoglobin level in the blood, ambient carbon monoxide levels would have an additive
effect on that carboxyhemoglobin level. Based on such information, a periodic post-shift
carboxyhemoglobin test as an index of the presence of carbon monoxide in the blood is
recommended, but not required, for medical surveillance.
Based on the animal evidence and three epidemiologic studies previously mentioned, OSHA
concludes that MC is a suspect human carcinogen. The medical surveillance program is designed
to observe exposed workers on a regular basis. While the medical surveillance program cannot
detect MC-induced cancer at a preneoplastic stage, OSHA anticipates that, as in the past, early
detection and treatments of cancers leading to enhanced survival rates will continue to evolve.
A. Medical and Occupational History
The medical and occupational work history plays an important role in the initial evaluation of
workers exposed to MC. It is therefore extremely important for the examining physician or other
licensed health care professional to evaluate the MC-exposed worker carefully and completely
and to focus the examination on MC’s potentially associated health hazards. The medical
evaluation must include an annual detailed work and medical history with special emphasis on
cardiac history and neurological symptoms.
An important goal of the medical history is to elicit information from the worker regarding potential
signs or symptoms associated with increased levels of carboxyhemoglobin due to the presence of
carbon monoxide in the blood. Physicians or other licensed health care professionals should
ensure that the smoking history of all MC exposed employees is known. Exposure to MC may
cause a significant increase in carboxyhemoglobin level in all exposed persons. However,
smokers as well as workers with anemia or heart disease and those concurrently exposed to
carbon monoxide are at especially high risk of toxic effects because of an already reduced oxygen
carrying capacity of the blood.
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A comprehensive or interim medical and work history should also include occurrence of
headache, dizziness, fatigue, chest pain, shortness of breath, pain in the limbs, and irritation of the
skin and eyes.
In addition, it is important for the physician or other licensed health care professional to become
familiar with the operating conditions in which exposure to MC is likely to occur. The physician or
other licensed health care professional also must become familiar with the signs and symptoms
that may indicate that a worker is receiving otherwise unrecognized and exceptionally high
exposure levels of MC.
An example of a medical and work history that would satisfy the requirement for a comprehensive
or interim work history is represented by the following:
The following is a list of recommended questions and issues for the self-administered
questionnaire for methylene chloride exposure.
QUESTIONNAIRE FOR METHYLENE CHLORIDE EXPOSURE
I. Demographic Information
1. Name
2. Date
3. Date of Birth
4. Age
5. Present occupation
6. Sex
7. Race (Check all that apply)

a. White ____                                                           d. Hispanic or Latino ____
b. Black or African American ____                           e. American Indian or Alaska Native ____
c. Asian ____                                                            f. Native Hawaiian or Other Pacific Islander
____
II. Occupational History
1. Have you ever worked with methylene chloride, dichloromethane, methylene dichloride, or
CH2Cl2 (all are different names for the same chemical)? Please list which on the occupational
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history form if you have not already.
2. If you have worked in any of the following industries and have not listed them on the
occupational history form, please do so.
Furniture stripping
Polyurethane foam manufacturing
Chemical manufacturing or formulation
Pharmaceutical manufacturing
Any industry in which you used solvents to clean and degrease equipment or parts
Construction, especially painting and refinishing
Aerosol manufacturing
Any industry in which you used aerosol adhesives
3. If you have not listed hobbies or household projects on the occupational history form, especially
furniture refinishing, spray painting, or paint stripping, please do so.
III. Medical History
A. General
1. Do you consider yourself to be in good health? If no, state reason(s).
2. Do you or have you ever had:
a. Persistent thirst
b. Frequent urination (three times or more at night)
c. Dermatitis or irritated skin
d. Non-healing wounds
3. What prescription or non-prescription medications do you take, and for what reasons?
4. Are you allergic to any medications, and what type of reaction do you have?
B. Respiratory
1. Do you have or have you ever had any chest illnesses or diseases? Explain.
2. Do you have or have you ever had any of the following:
a. Asthma
b. Wheezing
c. Shortness of breath
3. Have you ever had an abnormal chest X-ray? If so, when, where, and what were the findings?

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4. Have you ever had difficulty using a respirator or breathing apparatus? Explain.
5. Do any chest or lung diseases run in your family? Explain.
6. Have you ever smoked cigarettes, cigars, or a pipe? Age started:
7. Do you now smoke?
8. If you have stopped smoking completely, how old were you when you stopped?
9. On the average of the entire time you smoked, how many packs of cigarettes, cigars, or bowls
of tobacco did you smoke per day?
C. Cardiovascular
1. Have you ever been diagnosed with any of the following: Which of the following apply to you
now or did apply to you at some time in the past, even if the problem is controlled by medication?
Please explain any yes answers (i.e., when problem was diagnosed, length of time on
medication).
a. High cholesterol or triglyceride level
b. Hypertension (high blood pressure)
c. Diabetes
d. Family history of heart attack, stroke, or blocked arteries
2. Have you ever had chest pain? If so, answer the next five questions.
a. What was the quality of the pain (i.e., crushing, stabbing, squeezing)?
b. Did the pain go anywhere (i.e., into jaw, left arm)?
c. What brought the pain out?
d. How long did it last?
e. What made the pain go away?
3. Have you ever had heart disease, a heart attack, stroke, aneurysm, or blocked arteries
anywhere in you body? Explain (when, treatment).
4. Have you ever had bypass surgery for blocked arteries in your heart or anywhere else? Explain.
5. Have you ever had any other procedures done to open up a blocked artery (balloon
angioplasty, carotid endarterectomy, clot-dissolving drug)?

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6. Do you have or have you ever had (explain each):
a. Heart murmur
b. Irregular heartbeat
c. Shortness of breath while lying flat
d. Congestive heart failure
e. Ankle swelling
f. Recurrent pain anywhere below the waist while walking
7. Have you ever had an electrocardiogram (EKG)? When?
8. Have you ever had an abnormal EKG? If so, when, where, and what were the findings?
9. Do any heart diseases, high blood pressure, diabetes, high cholesterol, or high triglycerides run
in your family? Explain.
D. Hepatobiliary and Pancreas
1. Do you now or have you ever drunk alcoholic beverages?
Age started: ____ Age stopped: ____.
2. Average numbers per week:
a. Beers: ____, ounces in usual container:
b. Glasses of wine: ____, ounces per glass:
c. Drinks: ____, ounces in usual container:
3. Do you have or have you ever had (explain each):
a. Hepatitis (infectious, autoimmune, drug-induced, or chemical)
b. Jaundice
c. Elevated liver enzymes or elevated bilirubin
d. Liver disease or cancer
E. Central Nervous System
1. Do you or have you ever had (explain each):
a. Headache
b. Dizziness
c. Fainting
d. Loss of consciousness
e. Garbled speech
f. Lack of balance

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g. Mental/psychiatric illness
h. Forgetfulness
F. Hematologic
1. Do you have, or have you ever had (explain each):
a. Anemia
b. Sickle cell disease or trait
c. Glucose-6-phosphate dehydrogenase deficiency
d. Bleeding tendency disorder
2. If not already mentioned previously, have you ever had a reaction to sulfa drugs or to drugs
used to prevent or treat malaria? What was the drug? Describe the reaction.
B. Physical Examination
The complete physical examination, when coupled with the medical and occupational history,
assists the physician or other licensed health care professional in detecting pre-existing conditions
that might place the employee at increased risk, and establishes a baseline for future health
monitoring. These examinations should include:
1. Clinical impressions of the nervous system, cardiovascular function and pulmonary function,
with additional tests conducted where indicated or determined by the examining physician or other
licensed health care professional to be necessary.
2. An evaluation of the advisability of the worker using a respirator, because the use of certain
respirators places an additional burden on the cardiopulmonary system. It is necessary for the
attending physician or other licensed health care professional to evaluate the cardiopulmonary
function of these workers, in order to inform the employer in a written medical opinion of the
worker's ability or fitness to work in an area requiring the use of certain types of respiratory
protective equipment. The presence of facial hair or scars that might interfere with the worker's
ability to wear certain types of respirators should also be noted during the examination and in the
written medical opinion.
Because of the importance of lung function to workers required to wear certain types of respirators
to protect themselves from MC exposure, these workers must receive an assessment of
pulmonary function before they begin to wear a negative pressure respirator and at least annually
thereafter. The recommended pulmonary function tests include measurement of the employee's
forced vital capacity (FVC), forced expiratory volume at one second (FEV 1), as well as calculation
of the ratios of FEV1 to FVC, and the ratios of measured FVC and measured FEV 1 to expected
respective values corrected for variation due to age, sex, race, and height. Pulmonary function
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evaluation must be conducted by a physician or other licensed health care professional
experienced in pulmonary function tests.
The following is a summary of the elements of a physical exam which would fulfill the
requirements under the MC standard:
PHYSICAL EXAM
I. Skin and appendages
1. Irritated or broken skin
2. Jaundice
3. Clubbing cyanosis, edema
4. Capillary refill time
5. Pallor
II. Head
1. Facial deformities
2. Scars
3. Hair growth
III. Eyes
1. Scleral icterus
2. Corneal arcus
3. Pupillary size and response
4. Fundoscopic exam
IV. Chest
1. Standard exam
V. Heart
1. Standard exam
2. Jugular vein distension
3. Peripheral pulses
VI. Abdomen
1. Liver span
VII. Nervous System
1. Complete standard neurologic exam
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VIII. Laboratory
1. Hemoglobin and hematocrit
2. Alanine aminotransferase (ALT, SGPT)
3. Post-shift carboxyhemoglobin
IX. Studies
1. Pulmonary function testing
2. Electrocardiogram
An evaluation of the oxygen carrying capacity of the blood of employees (for example by
measured red blood cell volume) is considered useful, especially for workers acutely exposed to
MC.
It is also recommended, but not required, that end of shift carboxyhemoglobin levels be
determined periodically, and any level above 3% for non-smokers and above 10% for smokers
should prompt an investigation of the worker and his workplace. This test is recommended
because MC is metabolized to CO, which combines strongly with hemoglobin, resulting in a
reduced capacity of the blood to transport oxygen in the body. This is of particular concern for
cigarette smokers because they already have a diminished hemoglobin capacity due to the
presence of CO in cigarette smoke.
C. Additional Examinations and Referrals
1. Examination by a Specialist
When a worker examination reveals unexplained symptoms or signs (i.e. in the physical
examination or in the laboratory tests), follow-up medical examinations are necessary to assure
that MC exposure is not adversely affecting the worker's health. When the examining physician or
other licensed health care professional finds it necessary, additional tests should be included to
determine the nature of the medical problem and the underlying cause. Where relevant, the
worker should be sent to a specialist for further testing and treatment as deemed necessary.
The final rule requires additional investigations to be covered and it also permits physicians or
other licensed health care professionals to add appropriate or necessary tests to improve the
diagnosis of disease should such tests become available in the future.
2. Emergencies
The examination of workers exposed to MC in an emergency should be directed at the organ
systems most likely to be affected. If the worker has received a severe acute exposure,
hospitalization may be required to assure proper medical intervention. It is not possible to
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precisely define "severe," but the physician or other licensed health care professional's judgment
should not merely rest on hospitalization. If the worker has suffered significant conjunctival, oral,
or nasal irritation, respiratory distress, or discomfort, the physician or other licensed health care
professional should instigate appropriate follow-up procedures. These include attention to the
eyes, lungs and the neurological system. The frequency of follow-up examinations should be
determined by the attending physician or other licensed health care professional. This testing
permits the early identification essential to proper medical management of such workers.
D. Employer Obligations
The employer is required to provide the responsible physician or other licensed health care
professional and any specialists involved in a diagnosis with the following information: a copy of
the MC standard including relevant appendices, a description of the affected employee's duties as
they relate to his or her exposure to MC; an estimate of the employee's exposure including
duration (e.g., 15hr/wk, three 8-hour shifts/wk, full time); a description of any personal protective
equipment used by the employee, including respirators; and the results of any previous medical
determinations for the affected employee related to MC exposure to the extent that this
information is within the employer's control.
E. Physicians' or Other Licensed Health Care Professionals' Obligations
The standard in this section requires the employer to ensure that the physician or other licensed
health care professional provides a written statement to the employee and the employer. This
statement should contain the physician's or licensed health care professional's opinion as to
whether the employee has any medical condition placing him or her at increased risk of impaired
health from exposure to MC or use of respirators, as appropriate. The physician or other licensed
health care professional should also state his or her opinion regarding any restrictions that should
be placed on the employee's exposure to MC or upon the use of protective clothing or equipment
such as respirators. If the employee wears a respirator as a result of his or her exposure to MC,
the physician or other licensed health care professional's opinion should also contain a statement
regarding the suitability of the employee to wear the type of respirator assigned. Furthermore, the
employee should be informed by the physician or other licensed health care professional about
the cancer risk of MC and about risk factors for heart disease, and the potential for exacerbation
of underlying heart disease by exposure to MC through its metabolism to carbon monoxide.
Finally, the physician or other licensed health care professional should inform the employer that
the employee has been told the results of the medical examination and of any medical conditions
which require further explanation or treatment. This written opinion must not contain any
information on specific findings or diagnosis unrelated to employee's occupational exposures.
The purpose in requiring the examining physician or other licensed health care professional to
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supply the employer with a written opinion is to provide the employer with a medical basis to assist
the employer in placing employees initially, in assuring that their health is not being impaired by
exposure to MC, and to assess the employee's ability to use any required protective equipment.
[62 FR 1601, Jan. 10, 1997, as amended at 62 FR 42667, Aug. 8, 1997; 62 FR 54383, Oct. 20,
1997; 62 FR 66277, Dec. 18, 1997; 63 FR 1295, Jan. 8, 1998; 63 FR 20099, Apr. 23, 1998; 63 FR
50729, Sept. 22, 1998; 71 FR 16674, Apr. 3, 2006; 71 FR 50190, Aug. 24, 2006; 73 FR 75587,
Dec. 12, 2008; 77 FR 17785, Mar. 26, 2012; 78 FR 9313, Feb. 8, 2013; 84 FR 21544, May 14,
2019]
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