Refined oils include benzene, toluene, ethylbenzene and xylenes (BTEX); all are Volatile Organic Compounds (VOCs) and harmful to both human and aquatic life if absorbed. Refined oils are derivatives found in petroleum. There are unfortunately a multitude of ways through which refined oils can enter water courses, most prominently as a result of spills and leaks. As refined oils are slow to degrade which can cause them to accumulate in high concentrations in water.
