Section 4.05 Attachment A SRS Manual
OSHA Hazard Communication, 29 CFR 1910.1200, Appendices A and B
Health Hazard Definitions
Although safety hazards related to the physical characteristics of a chemical can be objectively defined in terms of testing requirements (e.g., flammability), health hazard definitions are less precise and more subjective. Health hazards may cause measurable changes in the body such as decreased pulmonary function. These changes are generally indicated by the occurrence of signs and symptoms in the exposed employees such as shortness of breath, which is a non-measurable, subjective feeling. Employees exposed to such hazards must be apprised of both the change in body function and the signs and symptoms that may occur to signal that change.
The determination of occupational health hazards is complicated by the fact that many of the effects or signs and symptoms occur commonly in non-occupationally exposed populations, so that effects of exposure are difficult to separate from normally occurring illnesses. Occasionally, a substance causes an effect that is rarely seen in the population at large such as angiosarcomas caused by vinyl chloride exposure, thus making it easier to ascertain that the occupational exposure was the primary causative factor. More often, however, the effects are common, such as lung cancer. The situation is further complicated by the fact that most chemicals have not been adequately tested to determine their health hazard potential, and data do not exist to substantiate these effects.
There have been many attempts to categorize effects and to define them in various ways. Generally, the terms "acute" and "chronic" are used to delineate between effects on the basis of severity or duration. "Acute" effects usually occur rapidly as a result of short-term exposures and are of high concentration but short duration. "Chronic" effects generally occur as a result of lower exposure levels and are of long duration.
The acute effects, such as irritation, corrosivity, sensitization and lethal dose, referred to most frequently are those defined by the American National Standards Institute (ANSI) standard for Precautionary Labeling of Hazardous Industrial Chemicals (Z129.1-1988). Although these are important health effects, they do not adequately cover the considerable range of acute effects which may occur as a result of occupational exposure, such as narcosis. Similarly, the term chronic effect is often used to cover only carcinogenicity, teratogenicity and mutagenicity. These effects are obviously a concern in the workplace, but again do not adequately cover the area of chronic effects, excluding blood dyscrasias (such as anemia), chronic bronchitis and liver atrophy, for example.
The goal of defining precisely, in measurable terms, every possible health effect that may occur in the workplace as a result of chemical exposures cannot realistically be accomplished. This does not negate the need for employees to be informed of such effects and to be protected from them. For purposes of this section, any chemicals which meet any of the following definitions, are health hazards. However, this is not intended to be an exclusive categorization scheme. If there are available scientific data that involve other animal species or test methods, it must also be evaluated to determine the applicability of the OSHA Hazard Communication Standard.
1. Carcinogen
A chemical is considered to be a carcinogen if:
a. It has been evaluated by the International Agency for Research on Cancer (IARC) and is found to be a carcinogen or potential carcinogen; or
b. It is listed as a carcinogen or potential carcinogen in the lastest edition of the Annual Report on Carcinogens published by the National Toxicology Program (NTP); or
c. It is regulated by OSHA as a carcinogen.
2. Corrosive
A chemical that causes visible destruction of, or irreversible alterations in, living tissue by chemical action at the site of contact. For example, a chemical is considered to be corrosive if, when tested on the intact skin of albino rabbits by the method described by the U.S. Department of Transportation in Attachment A to 49 CFR part 173, it destroys or changes irreversibly the structure of the tissue at the site of contact following an exposure period of four (4) hours. This term shall not refer to action on inanimate surfaces.
3. Highly Toxic
A chemical is considered to be highly toxic if it falls within any of the following categories:
a. A chemical that has a median lethal dose (LD(50)) of 50 milligrams or less per kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each.
b. A chemical that has a median lethal dose (LD(50)) of 200 milligrams or less per kilogram of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between two (2) and three (3)kilograms each.
c. A chemical that has a median lethal concentration (LC(50)) in air of 200 parts per million by volume or less of gas or vapor, or two (2) milligrams per liter or less of mist, fume or dust when administered by continuous inhalation for one (1) hour (or less if death occurs within one [1] hour) to albino rats weighing between 200 and 300 grams each.
4. Irritant
A chemical, which is not corrosive, but which causes a reversible inflammatory effect on living tissue by chemical action at the site of contact is considered an irritant. A chemical is a skin irritant if, when tested on the intact skin of albino rabbits by the methods of 16 CFR 1500.41 for four (4) hours exposure or by other appropriate techniques, it results in an empirical score of five (5) or more. A chemical is an eye irritant if so determined under the procedure listed in 16 CFR 1500.42 or other appropriate techniques.
5. Sensitizer
A chemical that causes a substantial proportion of exposed people or animals to develop an allergic reaction in normal tissue after repeated exposure to the chemical is considered a sensitizer.
6. Toxic
A chemical is considered toxic if it falls within any of the following categories:
a. A chemical that has a median lethal dose (LD(50)) of more than 50 milligrams per kilogram but not more than 500 milligrams per kilogram of body weight when administered orally to albino rats weighing between 200 and 300 grams each.
b. A chemical that has a median lethal dose (LD(50)) of more than 200 milligrams per kilogram but not more than 1,000 milligrams per kilogram of body weight when administered by continuous contact for 24 hours (or less if death occurs within 24 hours) with the bare skin of albino rabbits weighing between two (2) and three (3) kilograms each.
c. A chemical that has a median lethal concentration (LC(50)) in air of more than 200 parts per million but not more than 2,000 parts per million by volume of gas or vapor, or more than two (2) milligrams per liter but not more than 20 milligrams per liter of mist, fume or dust, when administered by continuous inhalation for one (1) hour (or less if death occurs within one [1] hour) to albino rats weighing between 200 and 300 grams each.
7. Target organ effects
The following is a target organ categorization of effects which may occur, including examples of signs, symptoms and chemicals which have been found to cause such effects. These examples are presented to illustrate the range and diversity of effects and hazards found in the workplace, and the broad scope employers must consider in this area, but are not intended to be all-inclusive.
a. Hepatotoxins: Chemicals which produce liver damage
Signs and Symptoms: Jaundice; liver enlargement
Chemicals: Carbon tetrachloride; nitrosamines
b. Nephrotoxins: Chemicals which produce kidney damage
Signs and Symptoms: Edema; proteinuria
Chemicals: Halogenated hydrocarbons; uranium
c. Neurotoxins: Chemicals which produce primary toxic effects on the nervous system
Signs and Symptoms: Narcosis; behavioral changes; decrease in motor functions
Chemicals: Mercury; carbon disulfide
d. Agents which act on the blood or hemato-poietic system: Decrease hemoglobin function; deprive the body tissues of oxygen
Signs and Symptoms: Cyanosis; loss of consciousness
Chemicals: Carbon monoxide; cyanides
e. Agents which damage the lung: Chemicals which irritate or damage pulmonary tissue
Signs and Symptoms: Cough; tightness in chest; shortness of breath
Chemicals: Silica; asbestos
f. Reproductive Toxins: Chemicals which affect the reproductive capabilities, including chromosomal damage (mutations) and effects on fetuses (teratogenesis)
Signs and Symptoms: Birth defects; sterility
Chemicals: Lead; DBCP
g. Cutaneous Hazards: Chemicals which affect the dermal layer of the body
Signs and Symptoms: Defatting of the skin; rashes; irritation
Chemicals: Ketones; chlorinated compounds
h. Eye Hazards: Chemicals which affect the eye or visual capacity
Signs and Symptoms: Conjunctivitis; corneal damage
Chemicals: Organic solvents; acids
Hazard Determination
The quality of a hazard communication program is largely dependent upon the adequacy and accuracy of the hazard determination. The hazard determination requirement of this standard is performance-oriented. Chemical manufacturers, importers and employers evaluating chemicals are not required to follow any specific methods for determining hazards, but they must be able to demonstrate that they have adequately ascertained the hazards of the chemicals produced or imported in accordance with the criteria set forth in this Attachment.
Hazard evaluation is a process which relies heavily on the professional judgment of the evaluator, particularly in the area of chronic hazards. The performance-orientation of the hazard determination does not diminish the duty of the chemical manufacturer, importer or employer to conduct a thorough evaluation, examining all relevant data and producing a scientifically defensible evaluation. For purposes of this standard, the following criteria shall be used in making hazard determinations that meet the requirements of this standard.
1. Carcinogenicity: As described in paragraph (d)(4) and Attachment A of this section, a determination by the National Toxicology Program, the International Agency for Research on Cancer or OSHA, that a chemical is a carcinogen or potential carcinogen will be considered conclusive evidence for purposes of this section. In addition, however, all available scientific data on carcinogenicity must be evaluated in accordance with the provisions of this Attachment and the requirements of the rule.
2. Human data: Where available, epidemiological studies and case reports of adverse health effects shall be considered in the evaluation.
3. Animal data: Human evidence of health effects in exposed populations is generally not available for the majority of chemicals produced or used in the workplace. Therefore, the available results of toxicological testing in animal populations shall be used to predict the health effects that may be experienced by exposed workers. In particular, the definitions of certain acute hazards refer to specific animal testing results (see Attachment A).
4. Adequacy and reporting of data: The results of any studies which are designed and conducted according to established scientific principles, and which report statistically significant conclusions regarding the health effects of a chemical, shall be a sufficient basis for a hazard determination and reported on any Material Safety Data Sheet (MSDS). In vitro studies alone generally do not form the basis for a definitive finding of hazard under the OSHA Hazard Communication Standard since they have a positive or negative result rather than a statistically significant finding.
The chemical manufacturer, importer or employer may also report the results of other scientifically valid studies which tend to refute the findings of hazard.