Raht, to my request for cooperation in a medical study of lead workers.

Threshold Limit calculated from the formula 250* SiO, + S ** Cnstobalite Amorphous including natural diatomaceous earth Tremolite 20 5 SILICATES (less than 1 % crystalline silica) Asbestos 5 Mica 20 Soapstone 20 Talc 20 Portland Cement 50 GRAPHITE (natural) 15 "Inert" or Nuisance Particulates SOforlSmg/m5 whichever is See Appendix 0 the smaller) Conversion (actors mppcf x 35 3 -- million particles per cubic meter = particles per cc e> Millions of parlulis per cubic foot of air. based on tmpiiigcr sjtnplcs counted h> light-field techniques n The percentage of crystalline silica in the formula is the ainnimt determined from air borne samples, except in those instances in which other methods have been shown to be applicable See "Notice of Intended Changes These substances, with their corresponding values, compose those for which either a limit has been proposed for the first time, or for which a change in the Recommended* listing has been proposed In both cases, the proposed limits should be considered trial limits that will remain in this listing for a period of at least two years During this time, the previously Recom mended Limit will remain in effect If, after two years no evidence comes to light that questions the appropriateness ol the values herein, the values will be placed in the ' Recommended" list Documentation is available for each of these substances Substance ppm* mg/cu m1 Abate Boron tnbromide Bromine pentafluonde 4 Butyl mercaptan *C Cadmium oxide fume (as Cd) Camphor Chlorine Cyanogen 44C Dichloroacety- lene C Diethylene C Diethylene tnamine- Skin Diphenyl amine 44 Endosulfen (Thiodan) Skin * Ethyl mercaptan Fibrous glass 10 01 05 2 1 10 01 10 - 05 - 15 01 10 01 $ Heptane Indene Indium and com pounds, as In Iron salts, soluble, as Fe Methyl isoamyl ketone Methyl mercaptan Methyl silicate Octane Oil mist (particulate) Oil vapors Pentaerythritol (tetra- methylomethane) Pentane Petroleum distillates Propargyl alcohol-Skin RDX-Skm Stoddard solvent Styrene Tetraethyl lead (as Pb)-- Skin Tetramethyt lead (as Pb) --Skin Tnmethyl benzene Tungsten and com pounds, as W Soluble Insoluble Uranium, sol and insol compounds as U 500 10 100 0!

TETRAETHYL LEAD.

Leadburner Methyl Chloride Mercury Noise Painter Radiation (Ionizing) Shale Oil (Inactive Grc Sandblaster (Also other Tetraethyl Lead Tinners Wax Operations (Inactive group) .'

Leadburner Methyl Chloride Mercury Noise Painter Radiation (Ionizing) Shale Oil (Inactive Grc Sandblaster (Also other Tetraethyl Lead Tinners Wax Operations (Inactive group) .'

The preparation of the way, therefore, should be undertaken by the tetraethyl lead industry with the assistance of the appropriate oil company.

TEPP (tetraethyl pyrophosphate)............

Tetraethyl lead (as Pb| Skin Tebahydrofuran ...

(l,l,l,2,-Tetrachloro-2,2,-difiu6roethane. . 1,000 fL1,2,2-TetrachIoro-l,2-difluoroetbaoe-- 500 (Tetraethyl lead--Skin.................

Surgeon General which concluded "that there are at present no good grounds for prohibiting the use of ethyl (leaded) gasollne...provided that its distribution and uees are controlled by proper regulations.* | k t The 1925-26 committee was appointed after the industry suspended sale of leaded gasoline in May 1925, following some lead poisoning cases in a plant Involved In the manufacture and handling of tetraethyl lead.

I47, He considers lead tetraethyl and tetramethyl os absorbable through skin.

Top p. 147, He considers lead tetraethyl and tetramethyl os absorbable through skin.

Top p. 147, He considers lead tetraethyl and tetramethyl os absorbable through skin.

His work in this field began In the very eariy days of mass manufacture of automobiles with the purpose of achieving safety and high health standards in the manufacture and use of tetraethyl lead for gasoline, The excellent, record maintained In this area can he traced largely io work performed by Dr.

Id U.S.A. major use for batteries followed by tetraethyl lead; sheet and pipe not such used for bulldli^ despite present lov prices.