Clear Lake, located about 150 km north of San Francisco, California, USA, has long been a popular spot for fishermen. However, the lake became a major nuisance in the summer due to the explosive increase of tiny insects called gnats. To combat this, lake managers conducted extensive spraying of a newly developed insecticide called Dichloro-Diphenyl-Dichloroethane (DDD). DDD is a substance that destroys the adrenal cortex, which produces a hormone called cortin, causing endocrine disorders when it enters the human body. The Clear Lake incident became a pivotal factor in the creation of Silent Spring, widely regarded as the greatest environmental masterpiece of the 20th century.