Human skin color effects of tanning. Around the same age, women experience darkening of some areas of their skin. Human skin color fades with age. Humans over the age of thirty experience a decrease in melanin-producing cells by about 10% to 20% per decade as melanocyte stem cells gradually die. The skin of face and hands has about twice the amount of pigment cells as unexposed areas of the body, as chronic exposure to the sun continues to stimulate melanocytes. The blotchy appearance of skin color in the face and hands of older people is due to the uneven distribution of pigment cells
Diarylide pigment with the same coupling partners. The molecular structures of these molecules is more conjugated than represented in the images shown below. The pigments' colors can range from yellow to green. One of the most common diarylide yellow pigments is Pigment Yellow 12. Its CAS number is . Other diarylide yellow pigments include ‘’’yellow 13’’’ , ‘’’yellow 17’’’ and ‘’’yellow 83’’’ . These pigments share the same backbone and vary in color depending on substitution of the benzene rings. Worldwide production of color organic pigments was estimated to be about 250,000 metric tons (t) in 2006, with about 25%, or 62,500