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Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.
Earwax has antimicrobial properties that reduce the viability of bacteria and fungus in the human ear.
Side effects from substance abuse include nausea, dehydration, reduced productivitiy, and dependence. Though these effects usually worsen over time, the constant need for the substance often overcomes rational thinking.
Normal urine is sterile. It contains fluids, salts, and waste products. It is free of bacteria, viruses, and fungi.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.