Anaerobic lagoons have been shown to harbor and emit substances which can cause adverse environmental and health effects. These substances are emitted through two main pathways: gas emissions and lagoon overflow. Gas emissions are continuous (though the amount may vary based on the season) and are a product of the manure slurry itself. The most prevalent gasses emitted by the lagoon are: ammonia, hydrogen sulfide, methane, and carbon dioxide. Lagoon overflow is caused by faulty lagoons, such as cracks or improper construction, or adverse weather conditions, such as increased rainfall or strong winds. These overflows release harmful substances into the surrounding land and water such as: antibiotics, estrogens, bacteria, pesticides, heavy metals, and protozoa.