On January 30, 2015, the American Conference of Governmental Industrial Hygienists (ACGIH^®) announced the under study list for its Threshold Limit Values for Chemical Substances (TLV^®-CS) Committee.  The under study list includes, under other issues under study, “nanoscale primary particle notation.”  According to ACGIH^®, the under study list serves as “notification and invitation to interested parties to submit substantive data and comments to assist the committees in their deliberations.”  The TLV^®-CS Committee will consider only those comments and data that address issues of health and exposure, but not economic or technical feasibility.  ACGIH^® states that comments must be accompanied by copies of substantiating data, preferably in the form of peer-reviewed literature.  By July 31, 2015, ACGIH^® will update the TLV^®-CS Committee’s under study list into a two-tier list:

• Tier 1 consists of chemical substances and physical agents that may move forward as a notice of intent to change (NIC) or notice of intent to establish (NIE) in 2016, based on their status in the development process; and
• Tier 2 consists of chemical substances and physical agents that will not move forward, but will either remain on, or be removed from, the under study list in 2016.

ACGIH^® states that the best time to submit comments is in the early stages of the TLV^® development process, preferably while the substance or agent is on the under study list.

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