Arsenic poisoning occurs when a person ingests or inhales arsenic, a toxic element found in some pesticides, contaminated water, and certain foods. Symptoms can include nausea, vomiting, abdominal pain, and diarrhea. Long-term exposure may lead to more severe health issues, such as skin lesions, cancer, and damage to the nervous system. Diagnosis typically involves blood or urine tests to measure arsenic levels. Treatment may include removing the source of exposure and using chelation therapy to help eliminate arsenic from the body. Prevention focuses on ensuring safe drinking water and proper handling of pesticides containing arsenic.