Join Date: Dec 2004
Location: Where Fezz used to be...
Memorandum from Seiko 6/2/1997 RE: New SLU Resin Odor
Took a CE class a few years back and asked the instructor about the odor of the very high index lenses and if it was toxic. Her reply was "that's the smell of money". So I again asked if it was toxic and she said only in extremely high concentrations that no lab environment could produce which made me curious as to how high extremely high was.
Found a lab who faxed me the following Seiko Memorandum addressed to Distribution.
"AS you may have had inquires from your customers regarding the odor of our new.......
In reviewing the Material Safety Data Sheet (MSDA), hydrogen sulfide is the only classified chemical class with an established threshhold limit value (TLV). This occupational exposure limit is set by the American Conference of Governmental Industrial Hygenists. The actual TVL at time weighted average (TWA) is 10 parts per million (PPM) or 14mg/m[to the (3rd?)]. This TWA translates to a safe concentration level for a normal 8 hour workday and a 40 hour work week, to which nearly all workers are constantly and repeatedly exposed without any adverse health effect.
Seiko states that when our lenses are processed under the worst conditions (dry edger with no ventilation or air circulation), that only extremely small amounts of hydrogen sulfide are released. The actual measured results at 5-10 cm around the edging point are 0.01 PPM or less. This is to say the exposure is 1,000 times less than the TLV-TWA. Therefore, it would be safe to say that if a person in a three foot cubic room was to edge 100 lenses at the same time and exposed to that atmosphere all day for a 40 hour work week conditions would still be 10 times less than the established TLV amounts."
They proceed to recognize the lenses smell like rotten eggs when edged and suggest to wet edge, ventilate, use deoderizers and "problematic or sensitive employees could be advised to wear dust masks."
There is no mention of how thick the test lenses are.
P.S. According to "New Scientist" magazine on 7/28/2001 and "Biochemical Pharmacology" Vol. 62, 2001 flatulence (word for the day?) is primarily-- you guessed it(!) hydrogen sulphide
(Can a chemist among us confirm hydrogen sulfide and sulphide are the same? I'm hoping not!)