ASK LABS
By Joseph L. Bruneni

SOMETHING IN THE AIR

Q I am hoping you can help me. I have been working in an optometric office for 26 years. We are full service and operate in-house edging for 99 percent of our jobs. Lately I have heard that polycarb dust can be cancerous. Is this true? In addition, the newer high-tech lenses such as 1.67 and 1.71 emit a strong odor similar to airplane glue, which is so bad at times we have to close off the lab and open the windows. I am deeply concerned over this. I have called a few labs but they are not really informed on this matter.

A (Part one) Polycarbonate is NOT listed as a potential carcinogen. Although polycarbonate presents no chemical irritation potential to either eyes or the skin, polycarbonate dust may cause mechanical irritation if allowed to contact the eyes. Note: Gases and fumes evolved during thermal processing or decomposition of this material may irritate the eyes, skin, or respiratory tract.

--Denny DeCourcy, technical support manager, Vision-Ease Lens

A (Part two) The following information should be helpful in resolving concerns or inquiries regarding odors associated with 1.60/1.66/1.67 high index lenses. Hydrogen sulfide is the only classified chemical class with an established threshold limit value (TLV) set by the American Conference of Governmental Industrial Hygienists. The actual TLV is 10 parts per million (PPM). This translates to a safe concentration level for a normal eight-hour work day and 40-hour work week without any adverse health effects. When these high index lenses are processed under the worst conditions (dry edger with no air circulation or ventilation), only extremely small amounts of hydrogen sulfide are released, 1,000 times less than the TLV-TWA. If a person in a 3-cubic-foot room edged 100 lenses simultaneously and was exposed to that atmosphere all day for a 40-hour work week, conditions would still be 10 times less than the established TLV amounts. We suggest the following to minimize the smell of hydrogen sulfide (the sulfur smell of rotten egg).

• Use a wet edger whenever possible.
• If possible, process lenses in a ventilated area or use a fan to circulate air.
• Individuals with a hypersensitive sense of smell or other more serious respiratory problems (asthmatic or bronchial conditions) should wear dust/gas masks.
• The use of air deodorizers to limit odor may minimize effects to the nose.

In summary, tens of millions of pairs of these lenses are processed around the world annually and prolonged exposure to this odor, even under the worst possible conditions, will not have any physical harmful effects on a normal, healthy individual.

--Mike Rybacki, Seiko High Index

SECRET CODES

Q More and more, I see the symbol "CE" on optical products ranging from eyewear frames to contact lens packaging, and even on some eyewear accessory packaging. Can you explain what it stands for? I'm guessing "corrective eyewear" but it's just a guess. Am I close?

--Scott Lund, ABOC, Walmart Vision Centers

A The symbol CE is applied to a wide range of products, not just ophthalmic. It is a European Union fundamental safety requirement. As noted in the following Website, www.euroconform.com, the letters "CE" are an abbreviation of Conformité Européenne, French for European conformity.

--Dick Whitney, manager of ophthalmic lens design
and optical technology, AO*Sola

If you have a question you'd like to have answered in Ask the Labs, send it to Joseph L. Bruneni. Fax: 310-533-8165. Phone: 310-533-4975. E-mail: joe@bruneni.com.  Or mail questions to: Vision Consultants, 2908 Oregon Court, #I-2, Torrance, CA 90503. An archive of past Ask the Labs columns can be found on the Eyecare Business Website at www.eyecarebiz.com.