April 2000 - Kits:

If you are purchasing kits for your laboratory be certain you review the Material Safety Data Sheets (MSDS) before you purchase them. For example, the LaMotte dissolved oxygen kit contains cadmium powder. Cadmium powder is a select carcinogen and is a regulated metal. In our opinion this kit is inappropriate for middle school students and should only be used by high school students in a designated area such as a fumehood. One should also consider the rationale of using a toxic metal which is controlled by the EPA to test for dissolved oxygen. The waste generated by this test often ends up in the body of water being tested. Other water quality kits we have examined contain mercuric chloride, sodium azide and barium chloride. Consider the use of calculator- based interfaces connected to probes. These are available from Texas Instruments and Vernier. (see: Vendors).

Also consider the cost of disposal of unused kits. We are aware of one school district that incurred a disposal cost of over $3000 to dispose of 150 kits from the biology and chemistry labs.