This model is based on the in vitro skin model Skin2 [5] which had been discontinued in October 1996. It was further proposed by industry to apply the model in a tiered strategy to identify those chemicals that are predicted to be likely to be phototoxic in the 3T3-NRU-PT but are negative in vivo [6].
401(k) contribution rules. On a pretax basis, employees can't contribute above certain limits. In 2015, for instance, the limit is $18,000; those 50 and older can make additional catch-up contributions of $6,000.This money is not counted toward income, and all gains are tax-deferred. The limits are the same for Roth 401(k)s, though the contributions do count toward income and all gains are tax-free.But employees can sock away a lot more retirement cash if their company plan offers an after-tax option in a traditional 401(k).he limits are the same for Roth 401(k)s, though the contributions do count toward income and all gains are tax-free. But employees can sock away a lot more retirement cash if their company plan offers an after-tax option in a traditional 401(k).
Since January 1, 2006, U.S. employers have been allowed to amend their 401(k) plan document to allow employees to elect Roth IRA type tax treatment for a portion or all of their retirement plan contributions. The same change in law allowed Roth IRA type contributions to 403(b) retirement plans.or example, in tax year 2013, normal Roth IRA contributions are limited to $5,500 ($6,500 if age 50 or older); whereas, up to $17,500 could be contributed to a Roth 401(k) account, provided no other elective deferrals were taken for the tax year (no traditional 401(k) deferrals taken).