Posted By Sean Fraser Could someone enlighten me as to what TVL means on a US-based Materials Safety Data Sheet please? We think it might be the Occupational Exposure Limit (it was valued as mg/m3) but we need to be sure. If anyone knows of an Internet resource (free to use) that can explain all of the terms used in the US that would be much appreciated. Thank you.

Posted By Anju Aslam Hi THE THRESHOLD LIMIT VALUES (TLV) IS THE CONCENTRATION OF A PARTICULAR SUBSTANCE TO WHICH AN INDIVIDUAL CAN BE EXPOSED TO OVER A REFERANCE PERIOD OF TIME.IT IS MORE OR LESS THE SAME AS THE OEL ( OCCUPATIONAL EXPOSURE LIMITS). ALSO IT IS MEASURED EITHER IN PPM OR MILLIGRAM PER CUBIC METRES. REGARDS, ANJU

Posted By Jay Joshi There is an excellent paper, "OELs and the effective control of exposure to substances hazardous to health in the UK" by Dr Mark Piney HM Principal Specialist Inspector (Occupational Hygiene)Date: October 2001; on the HSE website. http://www.hse.gov.uk/hthdir/noframes/oel.pdf The Abstract to this paper states:- "Before OELs existed regulations, based on specification standards, were used to try to control exposure to hazardous substances. OELs were first proposed by Elmhurst Duckering in the UK, as a way of limiting exposure to dust, in 1910. But, in practice, OELs were developed, applied and promulgated by industrial hygienists in the USA, the ACGIH TLVs being the most famous and influential standards. This paper covers the early control of hazardous substances, the development of TLVs and UK OELs, how reasonably practicable OELs are set and discusses a range of issues raised by the development, definitions and use of OELs. There are no conclusions or recommendations as the paper is a contribution to the current debate on the UK OEL Framework.