Safety toxicity after repeat exposure

Espenes, A., Aasen, J., Hetland, D., Satake, M., Smith, A., Eraker, N., and Aune, T. Toxicity of YTX in mice after repeated oral exposure. In Molluscan Shellfish Safety. Henshilwood, K., Deegan, B., McMahon, T., Cusack, C., Keaveney, S., Silke, J., O Cinneide, M., Lyons, D., and Hess, R, Eds. Proceedings of the 5th International Conference on Molluscan Shellfish Safety, Galway, Ireland, June 14-18, 2004, pp. 419 23, 2006. 

In the safety evaluation of chemicals, acute toxicity tests are those that evaluate effects occurring within about 7 days of a single dose, and sub-chronic toxicity tests evaluate toxicity resulting from short-term repeated dosing or exposure, often 28 days up to 90 days. Chronic toxicity tests are those that evaluate effects occurring after much longer exposures, at least six months and possibly up to the lifetime in experimental animals. 

The TLV represents the concentration under which it is believed that nearly all workers may be repeatedly exposed day after day without adverse effect, that is for 8 hours/ day, 40 hours/week. Apart from carbon dioxide (threshold limit value 5000 ppm) and simple asphyxiants such as nitrogen, the highest threshold limit value (least toxic) is 1000 ppm. A threshold limit value of 1000 ppm has been assigned for some fluorocarbons, and comparative data suggest similar values are reasonable for the other fluorocarbons discussed in this section. In many cases, the threshold limit values as established by the ACGIH have been adopted by the U.S. Occupational Safety and Health Administration (OSHA) as workplace exposure limits. See 29 CFR 1910.1000. [13]... 

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