Which life stage is often defined by physical changes increased decision making and search for self?

Midlife is the life stage which is often defined by a feeling of having a set course in life and an established career. It is the person's central period in life, ranging from the ages 40 to 65. During this stage, adults may have new responsibilities in the job and often feel the need to change their career standing while feeling that they still have more time. This is also known as "midlife crisis" which refers to a time when the adults are figuring out their morality and the remaining years to be productive in life.  

explanation:

allergens: overstimulate the nerve system

neurotics: attack nerve cells

mutagens: damage or otherwise alter dna sequence

generators: cause defects during growth and development  

carcinogens: cause unchecked cell growth

i hope you get the idea according to me these are the effects that happened.