Parabens are synthetically produced preservatives and are used especially in the cosmetic industry in order to maintain the integrity of water-based cosmetics. That's why some cosmetic companies started to produce cosmetics in a solid state, which reduces the presence of parabens in formulas.
There were some studies which proved the presence of parabens in breast cancer (especially methyl paraben). According to the Federal Drug Administration (FDA), a safe level of parabens is one which does not go beyond 25% of a cosmetic's formula.
Lead is very often found in lipstick. The presence of lead in human body can cause behavioural problems and affect the development of a fetus.