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| June 2005 |
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Feature |
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| But Wait ! We Don’t Use Mercury! |
| Mercury is used in switches but not anywhere else, right? In the case of electronics the most visible use of mercury has been in switches where visible amounts of mercury are used. What is less known is that small quantities of mercury are used as catalysts for polyurethanes not just in electronics but in a broad set of applications outside of the electronics industry. The composition section of a material safety data sheet for a polyurethane elastomer is reproduced in Table 1. The amount of mercury reported as phenylmercuric neodecanoate is 765 ppm Hg in the as-delivered mixture (phenylmercuric neodecanoate is 45 percent by mass mercury).
In Rhode Island no mercury-added product can be offered for sale after July 1 if it contains one gram of mercury or is formulated with 250 ppm mercury. The restrictions are set to even lower concentrations for future years (see Figure 2). The amount of mercury in the polyurethane example is more than three times the limit allowed under the Rhode Island statutes after July 1, 2005.
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| Table 1 — From Polyurethane Elastomer MSDS, Section 2, Composition / Information on Ingredients |
| Component |
CAS Number |
ACGIH TWA |
Exposure Limits OSHA PEL |
Weight Percent (%) |
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New Jersey Trade Secret
#221290880-5006P
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–
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None Established
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None Established
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40-45
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New Jersey Trade Secret #221290880-5050P
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–
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None Established
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None Established
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55-60
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Phenylmercuric neodecanoate
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26545-
49-3
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0.01 mg/m3
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0.01 mg/m3
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0.17
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Some suppliers that purchased polyurethane as ready-to-use materials from their suppliers did not realize that mercury was used as a catalyst. Even if they did know the mercury was used as a catalyst, the supplier may not have known that mercury was a substance of concern. All polyurethanes are a potential source of mercury in finished products and should be suspect until proven clear of mercury. In addition, any intentional use, even uses below the restrictions, must be reported to the state.
In any case, manufacturers need to know that mercury has been used in their products. In addition, mercury is covered by several other regulations internationally such as the European directive restricting hazardous substances, known as RoHS. Suppliers may not know all of the regulations that cover the products using their components.
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