Terms and Definitions

ACGIH - American Conference of Governmental Industrial Hygienists http://www.acgih.org/ is an organization that is responsible for creating TLV exposure guidelines. Atmospheric Hazards - Any substance that people introduce into the atmosphere that has damaging effects on living things and the environment is considered air pollution. Air pollution occurs when harmful substances including particulates and biological molecules are introduced into Earth's atmosphere. It may cause diseases, allergies or death in humans; it may also cause harm to other living organisms such as animals and food crops, and may damage the natural or built environment.

A-weighted decibels (dBA) - The relative measure of loudness of sounds in the air that are perceived by the human ear. The sound level (dBA) created by a task over an eight-hour work day. See the following table for permissible noise exposures under OSHA 29 CFR 1910.195. here

Permissible Noise Exposures (Source: OSHA 29 CFR 1910.195)

Duration per day (hours) Sound level, dBA Slow Response
8 90
6 92
4 95
3 97
2 100
1.5 102
1 105
0.5 110
< 0.25 115

Aquatic toxicity - The effects of a compound to organisms living in the water and is usually determined on organisms representing the three trophic levels, i.e. vertebrates (Fish: fathead minnows, rainbow trout or golden shiners), invertebrates (crustaceans as Daphnia spp.) and plants (Pseudokirchneriella subcapitata, Anabaena flos-aquae, Navicula pelliculosa, Skeletonema costatum, green algae).
Acute fish LC50 (mg/l)
Acute algal (or other aquatic plant) EC50 (mg/l)

Biodegradation - A process by which organic substances are decomposed by micro-organisms (mainly aerobic bacteria) into simpler substances such as carbon dioxide, water and ammonia. The 28-day studies are based on dissolved organic carbon, oxygen depletion or CO2 generation. www.cfpub.gov

Bioconcentration Factor (BCF) - The chemical concentration of a substance in an organism's tissue, divided by its equilibrium concentration in water expressed in equivalent units. www.archive.epa.org www.iaspub.epa.org

Biological Oxygen Demand (BOD) half-life- The amount of oxygen per unit volume of water required to bacterially or chemically oxidize (stabilize) the oxidizable matter in water. Biochemical oxygen demand measurements are usually conducted over specific time intervals (5, 10, 20, 30 days). The term BOD generally refers to a standard 5-day BOD test.

Carcinogen - A substance or mixture of substances which induce or increase the chance of cancer. A chemical is considered a carcinogen if it has been evaluated by IARC, listed by the National Toxicology Program (NTP), or regulated by OSHA as a carcinogen. www.osha.gov

CAS - Chemical Abstract Service is a coding system that provides a chemical identity. www.osha.gov

Dermal Irritation - A reversible or irreversible effect on the skin caused by a toxicant. www.osha.gov

P2OASys Score Description
2 Non-irritating; Adequate data available, and negative studies, no structural alerts, and GHS not classified.
4 Evidence in humans and animals shows slight or minor reversible skin irritation effects
8 Evidence in humans or animals shows reversible skin irritation effects; Irritant.
10 Existing human and animal data, in vitro data or information from structurally related compounds shows irreversible skin burns; Corrosive.

Developmental Toxicity - Adverse effects from exposure to a substance before conception or after that can be detected within the lifespan of an organism. Some effects can include death, structural abnormality, altered growth or function. www.epa.gov

Ecological Hazards - Hazards that impact the environment as a result of exposure to one or more environmental stressors (i.e. chemicals, land change, disease, invasive species and climate change).

EC50 - The effective concentration of a toxicant that causes 50% of the maximum response used to measure the potency.

Endocrine Disruptor - An exogenous substance or mixture that impacts and alters function(s) of the endocrine system. The endocrine system is a collection of glands that produce hormones that impact human health and functioning (i.e. metabolism, growth, development, tissue function, reproduction, sleep, and mood). The European Union (EU) prioritized chemicals into the following endocrine disrupting categories: www.epa.org

Environmental Fate & Transport - Where contamination is located and where it will likely flow given the unique set of geological, hydrological, biological and meteorological patterns at a site. Primarily used to evaluate human, ecological and environmental risks and to guide remediation decision-making. www.tools.niehs.nih.gov

EPA - Environmental Protection Agency www.epa.goc

Eye Irritation - A reversible or irreversible effect on the eyes caused by a toxicant. www.osha.gov

Category Description
1 Evidence of endocrine disrupting activity in at least one species using intact animals.
2 Endocrine Disrupting Potential; At least some in vitro evidence of biological activity related to endocrine disruption.
3a and 3b Substances for which there are no indications of endocrine-disrupting properties or which cannot be evaluated due to a lack of data.
P2OASys Score Description
2 Non-irritating; Adequate data available, and negative studies, no structural alerts, and GHS not classified.
4 Evidence in humans and animals shows slight or minor reversible eye irritation effects; Mildly irritating.
8 Evidence in humans or animals show reversible eye irritation from single or repeated exposure; Irritating.
10 Existing human and animal data, in vitro data or information from structurally related compounds shows irreversible eye damage; Irreversible.

Flashpoint - The minimum temperature at which a liquid gives off a vapor in sufficient concentration to ignite. www.osha.gov

GHS - Globally Harmonized System of Classification and Labelling of Chemicals www.osha.gov

GHS Category - A category that defines the level of a hazard based on criteria developed by the International Labor Organization (ILO) and United Nations Committee of Experts on the Transport of Dangerous Goods (UNCETDG) on quantitative data criteria. www.unece.org

Global Warming Potential (GWP) - Measurement used to compare the global warming impact of different gases to the relative amount of heat trapped by a similar mass of carbon dioxide over a specific time interval (20,100, or 500 years). Carbon dioxide’s GWP is standardized to 1 ton. www.epa.gov

Human Effects - A human health risk assessment is the process to estimate the nature and probability of adverse health effects in humans who may be exposed to chemicals in contaminated environmental media, now or in the future.

- Acute: Caused by the initial exposure of a hazardous chemical on a human or animal body. When a hazardous material's acute health effect is listed, the effects are generally severe and dangerous adverse effects, but subside after the exposure stops.

- Chronic - Adverse effect on animal or human body with symptoms that develop slowly, due to long and continuous exposure to low concentrations of a hazardous substance. Such symptoms do not usually subside when the exposure stops.

Read more: www.businessdictionary.com

HMIS- Hazardous Material Information System Label is a four-part colored label that uses numbers, letters and symbols to describe the hazards of a product.

Rating Guide Flammability Hazard Reactivity Hazard Health Hazard
4- Severe Hazard Very flammable or very volatile with flash points below 73°F and boiling points below 100°F. Readily capable of detonation or explosive decomposition at normal temperatures and pressures. Life threatening major or permanent damage may result from a single or repeated exposure.
3- Serious Hazard Materials capable of ignition under almost normal temperature. Flammable liquids with flash points below 73F and boiling points below 100F, as well as liquids with flash points at or above 73°F and below 100°F. Capable of detonation or explosive reaction, but the material requires a strong initiating source, needs to be heated, or reacts explosively with water. Major injury likely unless quick action is taken for medical treatment.
2- Moderate Hazard Must be moderately heated before ignition will occur. Flash points at or above 100°F and below 200°F. Normally unstable and will readily undergo violent chemical change, but no detonation or explosion. May react violently with water. Temporary or minor injury may occur.
1-Slight Hazard Materials which must be moderately heated before ignition will occur. Flash points at or above 100°F and below 200°F. Normally stable but can become unstable at high temps. And pressures. May react with water but no violent reactions. Irritation or minor reversible injury possible
0-Minimal Hazard Materials that are normally stable and do not burn unless heated. Normally stable even under fire conditions and will not react with water. No significant risk to health.

Hazard phrase (H-Phrase) - a phrase assigned to a hazard class and category that describes the degree of the hazard.

IARC - International Agency for the Research on Cancer www.iarc.fr

IDLH - Immediately dangerous to life and health. www.cdc.gov

ILO - International Labor Organization www.ilo.org

IOMC - The Inter-Organization Programme for the Sound Management of Chemicals (IOMC) www.who.int

Irritation - Surface reaction on the skin, eye, or respiratory system that may occur immediately due to a chemical or mechanical source. Irritant responses can be concentration-driven. www.osha.gov

Key Phrases - GHS phrases that explain the hazard associated with the substance. LC50 - Lethal concentration required to kill 50% of the population. According to the OECD (Organization for Economic Cooperation and Development) Guidelines for the Testing of Chemicals, a traditional experiment involves groups of animals exposed to a concentration (or series of concentrations) for a set period of time (usually 4 hours). The animals are clinically observed for up to 14 days.

Table 1: Toxicity Classes: Hodge and Sterner Scale
Routes of Administration
Oral LD 50 Inhalation LC 50 Dermal LD 50
Toxicity Rating Commonly Used Term (single dose to rats) mg/kg (exposure of rats for 4 hours) ppm (single application to skin of rabbits) mg/kg Probable Lethal Dose for Man
1 Extremely Toxic 1 or less 10 or less 5 or less 1 grain (a taste, a drop)
2 Highly Toxic 1-50 10-100 5-43 4 ml (1 tsp)
3 Moderately Toxic 50-500 100-1000 44-340 30 ml (1 fl. oz.)
4 Slightly Toxic 500-5000 1000-10,000 350-2810 600 ml (1 pint)
5 Practically Non-toxic 5000-15,000 10,000-100,000 2820-22,590 1 litre (or 1 quart)
6 Relatively Harmless 15,000 or more 100,000 22,600 or more 1 litre (or 1 quart)
Table 2: Toxicity Classes: Gosselin, Smith and Hodge
Probable Oral Lethal Dose (Human)
Toxicity Rating or Class Dose For 70-kg Person (150 lbs)
6 Super Toxic Less than 5 mg/kg 1 grain (a taste - less than 7 drops)
5 Extremely Toxic 5-50 mg/kg 4 ml (between 7 drops and 1 tsp)
4 Very Toxic 50-500 mg/kg 30 ml (between 1 tsp and 1 fl ounce)
3 Moderately Toxic 0.5-5 g/kg 30-600 ml (between 1 fl oz and 1 pint)
2 Slightly Toxic 5-15 g/kg 600-1200 ml (between 1 pint to 1 quart)
1 Practically Non-Toxic Above 15 g/kg More than 1200 ml (more than 1 quart)

Life Cycle Factors - Is a technique to assess environmental impacts associated with all the stages of a product's life from raw material extraction through materials processing, manufacture, distribution, use, repair and maintenance, and disposal or recycling.

Mixture - Composition of two or more substances in which they do not react. www.osha.gov

mg/kg - Milligram per kilogram atsdr.cdc.gov

mg/l - Milligram per liter www.atsdr.cdc.gov

MSDS - "Material Safety Data Sheet" which is now referred to as a Safety Data Sheet (SDS). www.osha.gov

Mutagen - An agent that increases the occurrence of a permanent change in the amount or structure of the genetic material in a cell or organism. www.osha.gov

P2OASys Score Description
4 No data, but some grounds for concern.
6 Suspected of causing genetic defects; Suspected/Possible - May induce heritable mutations in human germ cells, positive evidence from tests in mammals and somatic cell tests, In vivo somatic genotoxicity supported by in vivo mutagenicity.
8 May cause genetic defects (exposure causes the hazard); May cause heritable genetic damage; Positive results in: In vivo heritable germ cell tests in mammals, human germ cell tests, in vivo somatic mutagenicity tests, combined with some evidence of germ cell mutagenicity.
10 Known/Presumed - Known to produce heritable mutations in human germ cells; positive evidence from epidemiological studies.

Neurotoxicity - Toxicity in the nervous system caused by organic and inorganic substances, called neurotoxins, that causes damage to the nervous tissue by altering normal activity in an organism. www.epa.gov

P2OASys Score Description
4 May cause drowsiness or dizziness; Vapours may cause drowsiness and dizziness; Transient target organ effects; Specific target organ toxicity - repeated exposure, Central Nervous System.
8 Target organ: Central Nervous System; PNS; Tremors; Gait disturbance; Specific target organ toxicity- repeated exposure, Central Nervous System; Specific target organ toxicity- single exposure, Central Nervous System.
10 Specific target organ toxicity - single exposure, Central Nervous System.

NFPA - The National Fire Protection Association is a United States trade association that creates and maintains private, copyrighted standards and codes for usage and adoption by local governments. www.nfpa.org

Rating Guide (Blue) Health Hazard (Red)Flammability Hazard (Yellow) Instability Hazard (White) Specific Hazard
4 - Extreme Hazard Highly Toxic. May be fatal on acute exposure. Extremely flammable gas or liquid. Flash point below 73 F. Explosive at room temperature. Oxidizer - OXY
Acid- Acid
Alkaki- ALK
Corrosive- COR
Radiation - ☢
3- Serious Hazard Toxic. Full protective personal protective equipment should be worn. Flammable. Flash point 73 F to 100 F. May detonate if shocked or heated under confinement or mixed with water.
2 - Moderate Hazard Breathing apparatus and face mask must be worn. Combustible. Requires moderate heating to ignite Flash Point below 200 F. Unstable. May react with water.
1-Slight Hazard Breathing apparatus may be worn. Slightly combustible. Requires strong heating to ignite. May react if heated or mixed with water.
0 - Minimal Hazard No precautions necessary. Will not burn under normal conditions. Normally stable. Does not react with water.

NIOSH - National Institute of Occupational Safety and Health is part of the Centers for Disease Control of the Public Health Service of the Department of Health and Human Services. It conducts research and development in occupational safety and health, advises OSHA in rulemaking, approves respirators and promotes health and safety training and education. www.cdc.gov

NOAEC - No-observed adverse effect level. www.osha.gov

OSHA - Occupational Safety and Health Administration is a branch of federal government charged with worker health and safety. www.osha.gov

Ozone depletor - a compound that is recognized as an ozone depleting substance (ODS) and are categorized into two groups under the Clean Air Act: Class 1and Class II. www.epa.gov

PEL - Permissible Exposure Limit. Legal limit in the United States for exposure of an employee to a chemical substance or physical agent such as loud noise. Permissible exposure limits are established by the Occupational Safety and Health Administration (OSHA). PELs are listed in 29 CFR 1910.1000. www.osha.gov

Persistence - A physical property of a chemical that allows it to exist for long periods of time in the environment and accumulate or pass from one species or the next. Chemicals can be transported through wind and water. www.epa.gov

Physical Properties - An aspect of matter that can be observed or measured without changing it.

ppm - parts per million www.atsdr.cdc

Process Factors - Looking into aspects of the operating process that can have an effect on worker or surroundings.

Proposition 65 - A 1986 Californian proposition that requires the state to publish a list of chemicals known to cause cancer, birth defects, or reproductive harm. The list is updated once a year and has 800+ chemicals. Businesses must notify Californians about significant amounts of chemicals in the products they purchase, in the home and workplace, that are released into the environment.

Psychosocial Hazard - An occupational hazard that place a person at risk of negative psychological, physical, and social well-being (i.e. work-related stress, burnout, depression, and fear). These hazards can arise from poor work design, organization and management, poor social context, or from the products being used during the task (World Health Organization). apps.who.int

Reactivity - The proclivity of a compound to chemically react with other substances or itself, resulting in the liberation of energy. Can cause the formation of toxic or corrosive materials, pressure buildup, and temperature fluctuations. www.ecu.edu

REL - Recommended Exposure Level developed by NIOSH. www.ecu.edu

Reproductive Toxicity - Effects from a substance that impacts the ability for an organism to reproduce and causes difficulty in development of its offspring. www.epa.gov

UNECE, 2013, Part 3

GHS Category Description
1A Known or presumed to cause effects on human reproduction or on development; (Known) Based on human evidence
1B (Presumed) Based on Experimental Animals; May damage fertility or the unborn child; May cause harm to breast-fed children.
2 Known or presumed to cause effects on human reproduction or on development; (Known) Based on human evidence.

SDS - Safety Data Sheet (See MSDS)

Sensitization - A reaction caused by a single or repeated exposure to a substance in normal tissue of an organism (i.e. dermal and respiratory sensitization). ww.osha.gov

Common Key Phrases: - May cause allergy or asthma symptoms or breathing difficulties if inhaled; - May cause sensitization by inhalation; - May cause sensitization by skin contact; - Substances showing a low to moderate frequency of occurrence in humans; - Probability of occurrence of a low to moderate sensitization rate in humans based on animal or other tests; Severity of reaction may also be considered - Sensitizer; Asthmagen; Substances showing a high frequency of occurrence in humans; or a probability of occurrence of a high sensitization rate in humans based on animals or other tests; Severity of reaction may also be considered

STOT - Specific target organ toxicity - single exposure/repeated exposure are non-lethal, but reversible or irreversible damage to specific organs after contact with a chemical. www.schc.org

T 1/2 days - The amount of time needed in days for a substance to reduce to half the amount of its previous level by degradation. medical-dictionary.thefreedictionary.com

Teratogen - A substance that causes structural or functional birth defect between conception and birth. www.atsdr.cdc.gov

TLV - Threshold Limit Values represent conditions under which it is believed that nearly all workers may be repeatedly exposed over a set time (days; working lifetime) without adverse effects due to airborne concentrations of a substance. www.osha.gov

TSCA - Toxic Substances Control Act www.epa.gov

TWA - Time Weighted Average is the concentration for a normal 8-hour working day (40 hours/week) to which workers may be exposed without anticipated adverse effect. www.osha.gov

Volatile Organic Compounds (VOCs) - Organic substances that are emitted as gases from certain solids and liquids that may cause short and long-term adverse health effects. VOCs participate in the atmospheric photochemical reactions that contribute to ozone formation. (EPA) www.epa.gov