Methylmercury (MeHg) is an organic form of mercury that can damage the developing brains of human fetuses. Women who consume methylmercury during pregnancy can bear children who have neurological issues because methylmercury has toxic effects on the nervous system during embryonic development. During the third week of gestation, the human nervous system begins to form in the embryo. During this gestational period, the embryo's nervous system is particularly susceptible to the influence of neurotoxins like methylmercury that can result in abnormalities. Furthermore, the fetal brain can incur damage despite the lack of signs of poisoning in the pregnant woman. In children, defects due to methylmercury can result in deficits in attention, behavior, cognition, and motor skills.
Gonorrhea is a sexually transmitted disease, or STD, caused by the bacterium Neisseria gonorrhoeae. Common symptoms of the disease include painful urination and genital discharge. There are records of historical discussions of gonorrhea in ancient civilizations and during the Middle Ages, but scientists did not begin investigating the scientific causes and treatments of the STD until the sixteenth century. In the 1700s, physicians attributed gonorrhea to the same cause as another STD, syphilis. Later, in the 1800s, researchers discovered the two diseases were not the same and identified the bacteria N. gonorrhoeae that causes gonorrhea. By the 1900s, researchers began using antibiotics to target the bacteria, but many drugs eventually developed antibiotic resistance. In 2020, the World Health Organization, or WHO, estimated that 82.4 million individuals contracted gonorrhea globally, and as of 2024, researchers continue to experiment with various antibiotic drugs to provide adequate treatment for the disease.