Dilauryl thiodipropionate (DLTDP) (chemical name: Didodecyl 3,3'-thiodipropionic acid, dilauryl ester of ß,ß'-thiodi-propionic acid, CAS No . 123-28-4) has a molecular weight of 514.85 and a characteristic sweet ester odor, and it occurs as white crystalline flakes. The white crystalline flakes have a characteristic ester odor. DLTDP may contain the following impurities: thiodipropionic acid, sulfated ash, arsenic, lead, or heavy metals. It is soluble in most organic solvents and insoluble in water.7-11 Its melting/solidification point is 40 ℃, and in solid form at 25 ℃. it has a specific gravity of 0.975. It conforms to the following structure:

DLTDP is used as an antioxidant in high-pressure greases and lubricants; it is used also as a softening agent and plasticizer. During the experiment, the inventors have found that some of the low toxicity, non-polluting substances (e.g., β- (3, 5- di-t-butyl-4-hydroxyphenyl) propionic acid n-octadecanol ester, tris (2,4-di-tert-butylphenyl) phosphite and dilauryl thiodipropionate) synergistic effect can be obtained, so that the antioxidant compound thus obtained of styrene after the thermoplastic elastomer can be greatly improved resistance to aging styrene-based thermoplastic elastomer, and anti-yellowing properties.

Dilauryl thiodipropionate (DLTDP)  is used as an antioxidant and sequestering agent in cosmetics and in foods. DLTDP is used in eye and face makeup products, in skin care and fragrance products, and in skin cleansing preparations at concentrations of up to 1 %. DLTDP is approved as a traditional cosmetic ingredient in Japan. Both DLTDP is considered GRAS food substances by the FDA, which is approved as direct food additives and used in food wraps and films. 

DLTDP is the diester of lauryl alcohol and 3,3'-thiodipropionic acid which is used as an antioxidant and sequestering agent in cosmetics at concentrations up to 1 %. When administered orally to rats and mice, DLTDP was slightly toxic and was relatively nontoxic in subchronic oral studies with rats. The safety test concentration used in dermal toxicity of DLTDP was 0.05%. The report limits its safety conclusion by concluding that DLTDP is safe for use in cosmetic products at the maximum dermal tested concentration of 0.05%.

Dilauryl thiodipropionate (DLTDP)  is slightly toxic when administered to mice and rats by the oral route. No irritation was produced by a make-up foundation containing 0.05% DLTDP. when tested at 0.0025% on intact and abraded skin of New Zealand white rabbits. A makeup foundation containing 0.05% DLTDP was not a sensitizer in a guinea pig maximization test.

Dilauryl thiodipropionate (DLTDP) , at a concentration of 0.05% in a makeup foundation, was not an irritant or a sensitizer when tested on 224 healthy human volunteers using a modified Draize Shelanski-Jordan patch test or in a supervised usage test with 30 subjects. The makeup foundation containing DLTDP was not a phototoxin or a photoallergen when tested in 27 healthy human volunteers.

References

1.Final Report on the Safety Assessment of Dilauryl Thiodipropionate, Journal of the American College of Toxicology, 11(1) 25-41, 1992.  
2.Antioxidant composition and its preparation method, styrene-based thermoplastic elastomer and its preparation method, CN103709439, 2012.
3.Diamante C, Fiume MZ, Bergfeld WF, Belsito DV, Hill RA, Klaassen CD, Liebler DC, Marks JG Jr, Shank RC, Slaga TJ, Snyder PW, Alan Andersen F.Final safety assessment of thiodipropionic acid and its dialkyl esters as used in cosmetics.  International Journal of Toxicology, 29(4), 137S-150S, 2010.
4.Stabilizing composition for organic polymers, US5155153, 1992.