California Code of Regulations › Title 8 - Industrial Relations › Division 1 - Department of Industrial Relations › Chapter 4 - Division of Industrial Safety › Subchapter 7 - General Industry Safety Orders › Group 16 - Control of Hazardous Substances › Article 110 - Regulated Carcinogens › Appendix B to Section 5202 - Medical Surveillance for Methylene chloride

Current through Register 2024 Notice Reg. No. 28, July 12, 2024
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 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 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 above, 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.
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. Social Security Number
3. Date
4. Date of Birth
5. Age
6. Present occupation
7. Sex
8. Race
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 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?
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)?
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
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
						  (FEV1), as well as calculation of the ratios of FEV1 to FVC, and the ratios of
						  measured FVC and measured FEV1 to expected respective values corrected for
						  variation due to age, sex, race, and height. Pulmonary function 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 distention
3. Peripheral pulses
VI. Abdomen
1. Liver span
VII. Nervous System
1. Complete standard neuralgic exam
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 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 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 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.
1. New
						  appendix B filed 8-4-97; operative 11-2-97 (Register 97, No.
						  32).
Note: Authority cited: Sections
							 142.3,
							 9020,
							 9030 and
							 9040, Labor
							 Code. Reference: Sections
							 142.3,
							 9004(d),
							 9009,
							 9020,
							 9031 and
							 9040, Labor
							 Code.