Document NG2pMQMmM0JZxg1e2J52xRRrw

Shell Oil Company Shell Chemical Company Interoffice Memorandum APRIL 29, 1986 OVG PLAINTIFF'S EXHIBIT SH-2328 FROM: P.0. SNYDER, SENIOR INDUSTRIAL HYGIENIST, HEALTH & SAFETY DEER PARK MANUFACTURING COMPLEX TO: - C. BATTS, PURCHASING DEER PARK MANUFACTURING COMPLEX SUBJECT: SELECTION OF SANDBLASTING GRIT Material used for sandblasting may contain two types of components which are of health significance, crystalline silica and certain toxic metals. When these materials are present, there is a likelihood of airborne exposure to these materials in excess of their particular permissible exposure limits (see below). Grit not containing such components is typically classified as a nuisance dust with a permissible exposure 1imit of 10 mg/m3. EXPOSURE LIMIT METALS (mg/m3) Chromium Metal Copper Inorganic Lead Nickel Vanadium 0.5 1.0 0.15 1.0 0.05 The exposure limit for silica dust is based upon the % silica present in the airborne dust. A direct correlation between the silica composition of the grit and the * silica in the airborne dust cannot be made without field analysis, however, it is reasonable to assume a close correlation. The following permissible limits for silica dust are provided to illustrate the effect that % silica has on the exposure limit. % SILICA TOTAL DUST LIMIT (mg/m3) 0 0.5 1.0 5.0 10.0 50.0 10.0 8.5 7.5 3.7 2.3 0.6 Additional reductions in the permissible limit associated with silica have been proposed. LAM 002382 CHBT8611304 DPMC-08537 2 Although all sandblasting operations require respiratory protection, the requirements for training, air sampling, medical surveillance as well as the potential for downwind exposure can be affected by the grit composition. It is important that grit, including those labeled as "silica free", be of such a composition that exposure to any component would routinely not exceed the applicable permissible limits. While a direct correlation between % composition and exposure levels cannot be made without extensive field-analysis, the following specifications are provided as a guideline to minimize the potential for exposure levels exceeding the applicable exposure limit. SPEC*(%) Crystalline silica Inorganic lead as Pb Nickel as Ni Chromium as Cr Cadmium as Cd Beryllium as Be Arsenic as As less than 1 0.1 0.1 0.1 0.01 0.1 0.01 Materials with greater than 1% crystalline silica are to be treated as silica grit. Materials not meeting the metal specifications are not to be used without, prior consultation with Industrial Hygiene. Thank you. .. . P.J. Snyder PJS/md cc: B.T. Waggoner ECB Satel1ite PJS Chron * As measured from a representative bulk sample of the grit supplied. LAM 002383 CHBT8611304 DPMC-08536