Used primarily as a biocide and preservative, especially in wood treatment to protect against fungal decay, termites, and other pests. Commonly applied in utility poles, railroad ties, and industrial timber where long-term durability is essential. Also found use in marine environments to prevent biofouling on structures. Its high chlorine content enhances stability and resistance to degradation, making it effective in harsh conditions. Due to toxicity and environmental persistence, its use is now restricted or banned in many countries, particularly in consumer products and residential settings. Historically used in antifouling paints and as a pesticide, but these applications have largely been phased out.