Recommended Exposure Levels RELs

Recommended Dietary Allowance (RDA), 17 652 25 784-787 of ascorbic acid, 25 772 defined, 25 784 for vitamins, 25 785t Recommended exposure level (REL), hydrazine, 13 590... 

For occupational exposures, Permissible Exposure Levels (PELs), Threshold Limit, Values (TLVs), and NIOSH Recommended Exposure Levels (RELs) are developed. They represent dose levels that will not produce adverse health effects from repeated daily exposures in the workplace. The method used to derive them is conceptually the same. Safety factors are used to derive the PELs, TLVs, and RELs. 

The (US) National Institute for Occupational Safety and Health (NIOSH) recommended exposure level (REL), averaged over a lOh workday is 0.005 ppm (0.035 mgm ). 

Recommended exposure level (REL) and permissible exposure levels (PEL) are levels below which it is uncommon to see health effects. REL are only recommended, while PEL can be strictly enforced. 

OSHA continues to recommend that employees exposure be limited to the more protective level of either the National Institute of Occupational Safety and Health (NIOSH) Recommended Exposure Levels (RELs) or the ACGIH TLVs. OSHA can issne citations for violation of the general duty clause [Section 654(a)(1)]. The general dnty clause states that each employer shall furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or likely to cause death or serious physical harm to his employees. ... 

EPA has established that hydrogen sulfide is a regulated toxic substance and is a hazardous substance as defined under the Federal Water Pollution Control Act. OSH A has established an acceptable ceiling concentration of 20 parts per million (ppm) for hydrogen sulfide in the workplace, with a maximum level of 50 ppm allowed for 10 minutes maximum duration if no other measurable exposure occurs. NIOSH has set a maximum Recommended Exposure Limit (REL) ceiling value (10 minutes) of 10 ppm. A complete listing of federal and state regulations and recommendations are found in Chapter 7. 

OSHA sets levels of cyanide that are allowable in workplace air. The permissible exposure limit (PEL) for cyanide salts is 5 milligrams of cyanide per cubic meter of air (mg/m3) averaged over an 8-hour workday and 40-hour workweek. NIOSH sets guidelines for chemicals in workplace air. Their recommended exposure limit (REL) for workers for 10 minutes is 5 mg/m3 for calcium cyanide, hydrogen cyanide, potassium cyanide, and sodium cyanide. 

Pretreatment Standards for New Sources REL = Recommended Exposure Level RfD = Reference Dose TLV = Threshold Limit Value TPQ = Threshold Planning Quantity TWA = Time- Weighted Average WHO =... 

REL Recommended Exposure Level average concentration limit recommended for up to a 10-hour workday during a 40-hour workweek, by NIOSH. 

OSHA = Occupational Safety and Health Administration OSW = Office of Solid Waste OTS = Office of Toxic Substances OWRS = Office of Water Regulations and Standards PEL = Permissible Exposure Level PIC = Products of Incomplete Combustion REL = Recommended Exposure Level SIP = State Implementation Plan SNARL = Suggested No Adverse Response Level STEL = Short-term Exposure Limit TLV = Threshold Limit Value TWA = Time-Weighted Average ... 

OSHA requires employers of workers who are occupationally exposed to 2-butoxyethanol to institute engineering controls and work practices to reduce employee exposure and maintain it at or below pennissible exposure limits (PEL). The PEL for 2-butoxyethanol is 50 ppm (OSHA 1974). Workers exposed to 2-butoxyethanol should wear personal protective equipment such as gloves, coveralls, and goggles to protect exposure to tire skin (OSHA 1974). NIOSH recommends that industrial hygiene surveys be completed at work places where airborne exposure to 2-butoxyethanol or 2-butoxyethanol acetate may occur (NIOSH 1990). If exposure levels are at or above one-half the recommended exposure limit (REL = 5 ppm), NIOSH recommends that a program of personal monitoring be instituted so that tlie exposure of each worker can be estimated. If exposure levels are at or greater than the REL, or if there is a potential for skin contact, NIOSH recommends that 2-butoxyacetic acid be measured in the urine of the workers. 

Emissions from individual sources can be closely regulated, both within a facility (occupational standards) and outside it (with New Source Performance Standards at the federal level and/or Air Toxic Hot Spots regulations in California). The National Institute of Occupational Safety and Health (NIOSH) began in 1970, with the passage of the Occupational Safety and Health Act, to develop recommended exposure limits (RELs) for chemicals in the workplace. In 1974, NIOSH joined with OSHA to update the OSHA program for PELs for a wide variety of substances, incorporating cancer potency data as it became available over subsequent years. Their evaluations were published in criteria documents. Special Hazard Reviews, and summarized in a Compendium of Policy Documents and Statements (NIOSH 1992). Available information is periodically updated in the NIOSH Pocket... 

To understand the proper level of respiratory protection, you must conduct a hazard assessment to define your potential workplace exposures. This assessment will define if the hazards are Immediately Dangerous to Life and Health (IDLH) or non-IDLH. This is critical information needed to define whether an air-purifying respirator (APR) is suitable or if an air supplied respirator is required. The National Institute for Occupational Safety and Health (NIOSH) Pocket Guide to Chemical Hazards (www.cdc. gov/niosh/npg/) is a comprehensive resource that will define IDLH levels for most hazards you will encounter. The Pocket Guide will also define specific characteristics of your hazard of concern as well as provide the NIOSH Recommended Exposure Limit (REL) and OSHA Permissible Exposure Limit (PEL). 

EL = emissions level ERA = Environmental Protection Agency HSDB = Hazardous Substances Data Bank lARC = International Agency for Research on Cancer IRIS = Integrated Risk Information System NIOSH = National Institute of Occupational Safety and Health OEL = occupational exposure limit OSHA = Occupational Safety and Health Administration PEL = permissible exposure limit RAC = reference air concentration REL = recommended exposure limit RCRA = Resource Conservation and Recovery Act RfD = reference dose TLV = threshold limit value TWA = time-weighted average WHO = World Health Organization... 

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