TLV Threshold Limit Values

us-stel in tlv

uk-ltel in tlv

mak in tlv

This is one of the fields contained within the Occupational Exposure superfield (ZOCE) which itself is associated with the Occupational Exposure message field (OE).

This field contains threshold limit data from the UK, France, Germany, Japan, Sweden and the USA and are presented in that order with each country's data beginning on a new line.

The full-stop is a searchable character in this field.

The airborne limits of permitted concentrations of hazardous chemicals represent conditions under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect. These limits are subject to periodic revision and vary between different countries. The term threshold limit relates primarily to the USA, but equivalent terms are available in most industrialised countries. In DOSE items, comparable values are available for the USA and United Kingdom. The data relate to concentrations of substances expressed in parts per million (ppm) and/or milligrams per cubic metre (mg m-3).

The threshold limit values for the USA have been taken from the Threshold Limit Values and Biological Exposure Indices, 1999 produced by the ACGIH (American Conference of Governmental Industrial Hygienists), Cincinnati, USA. The limits relate to Threshold Limit -Time Weighted Average (US-TWA in the data), Threshold Limit - Short Term Exposure Limit (US-STEL in the data) and Threshold Limit - Ceiling Limit. The Threshold Limit Value - Time Weighted Average (TLV-TWA) allows a time-weighted average concentration for a normal 8-hour working day and a 40-hour working week, to which nearly all workers may be repeatedly exposed day after day, without adverse effect. The Threshold Limit Value - Short Term Exposure Limit (TLV-STEL) is defined as a 15-minute, time-weighted average which should not be exceeded at any time during a working day, even if the 8-hour time-weighted average is within the TLV. It is designed to protect workers from chemicals which may cause irritancy, chronic or irreversible tissue damage, or narcosis which may increase the likelihood of accidental injury. For Threshold Limit - Ceiling Values (TLV-C) the concentration should not be exceeded during any part of the working day.

In the United Kingdom the occupational limits relating to airborne substances hazardous to health are published by the Health and Safety Executive annually in Guidance Note EH40. The values in DOSE have been taken from the 1999 edition.

In the United Kingdom, there are Maximum Exposure Limits (MEL) which are subject to regulation and which should not normally be exceeded. They derive from Regulations, Approved Codes of Practice, European Community Directives, or from the Health and Safety Commission. In addition, there are Occupational Exposure Standards (OES) which are considered to represent good practice and realistic criteria for the control of exposure. In an analogous fashion to the USA Threshold Limits, there are long-term limits (UK-LTEL in the data), expressed as time-weighted average concentrations over an 8-hour working day, designed to protect workers against the effects of long-term exposure. The short-term exposure limit (UK-STEL in the data) is for a time-weighted average of 15 minutes. For those substances for which no short-term limit is listed, it is recommended that a figure of three times the long-term exposure limit averaged over a 15-minute period be used as a guideline for controlling exposure to short-term excursions.

Swedish data from the Ordinance (AFS1966:2) of the Swedish National Board of Occupational Safety and Health, published in 1996, can include any of a short-term exposure limit, a level exposure limit or a ceiling limit, the acronyms for which are SE-STEL, SE-LEVL and SE-CEIL respectively.

German data currently includes the national MAK values (acronym is DE-MAK) where available. The MAK value (Maximum Arbeitsplatz Konzentration) is defined as a maximum permissible concentration of a chemical compound present in the air within a working area, which according to current knowledge, does not impair the health of the employee or cause undue annoyance. Under these conditions, exposure can be repeated and of long duration over a daily period of eight hours, constituting an average working week of 40 hours.

MAK values are those from the Deutsche Forschungsgemeinschaft, Bonn and published in "List of MAK and BAT Values 1999. Commission for the Investigation of Health Hazards of Chemical Compounds in the Work Area. Report No. 35".

Japanese exposure limits are those recommended by the Japanese Society of Occupational Health (J. Occup. Health 1996, Vol 38, p134-147). These values, unless otherwise indicated, are long-term exposure limits (the mean exposure concentration at or below which adverse health effects caused by the substance do not appear in most workers, working 8 hours a day, 40 hours a week under a moderate workload). The acronym used for this data is JP-OEL.

French exposure limits are those published in 1996 by the French ministry in charge of Labour and presented in the report Valeurs limites d'exposition professionelle aux agents chiques en France (ND 1945-153-93). The FR-VLE values are short-term limits (15 minutes), and FR-VME values are long-term limits (8 hours).

Units for Japanese, Swedish, German and French data are either ppm or mg m-3 (see above).

All the two character country code prefixes appearing above are taken from the ISO (International Standards Organisation) 3166 (1993) standard.