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).
Both a 401k and a Roth IRA have annual contribution limits. The contribution limit varies from year to year and is adjusted based on inflation. You can make the maximum contribution to both a 401k and a Roth IRA in the same year.ou contribute to a Roth IRA after taxes. That way you won't have to pay taxes on that money when you withdraw it after you retire. If you invest wisely and your Roth IRA increases in value, you will not have to pay taxes on the gains from your investment. Your 401k will be taxed after you retire.