There are lost of answers to this question. People can be exposed to chemicals in various ways and environments. Some common sources and pathways of chemical exposure include:
Occupational Exposure. Workers may come into contact with chemicals in industrial settings, factories, laboratories, agriculture, construction sites, and other work environments.
Environmental Exposure. Chemicals can be present in the air, water, and soil due to pollution from industrial activities, vehicle emissions, agricultural practices, waste disposal, and other sources. People can be exposed to these chemicals by breathing contaminated air, consuming contaminated food or water, or coming into direct contact with contaminated surfaces.
Consumer Products. Chemicals are used in the production of various consumer products such as cleaning agents, personal care products, cosmetics, furniture, electronics, and plastics. People can be exposed to chemicals through the use of these products, especially if they are not used or handled properly.
Residential Exposure. Chemicals may be present in homes and residential settings, including indoor air pollutants, pesticides, cleaning products, and building materials. Poor ventilation and improper use of chemicals in the home can increase exposure risks.
Medical Settings. Patients can be exposed to chemicals through medical procedures, treatments, and medications. Healthcare workers may also be exposed to chemicals in healthcare settings, such as disinfectants, sterilizing agents, and hazardous drugs.
Contaminated Sites. Living near or working in proximity to contaminated sites, such as landfills, industrial waste disposal areas, or former chemical manufacturing facilities, can lead to chemical exposure through soil, water, and air contamination.
Accidental Spills. Chemical spills, leaks, or accidents can occur during transportation, storage, or handling of chemicals, leading to potential exposure for nearby populations.
This is the best I could come with, hope it helps.