Polycyclic aromatic hydrocarbons, PAHs, are organic chemicals that enter the environment from various sources, such as asphalt, burning fossil fuels, forest fires, and oil spills. Once in the environment, PAHs can be found in soil, sediments, air, water, and fish. They are created by incomplete combustion, for example fossil fuels. They are known to cause cancer and mutations. However, PAHs are subject to chemical and photochemical reactions which renders them less toxic. Photosensitization produces highly reactive singlet oxygen by exciting PAHs. I used the PAH phenanthrene as a representative of all PAHs, since it is in the middle in terms of photodegradation abilities, and it is one of the simplest PAHs. Phenanthrene also has the same toxicity to the environment as other PAHs. It is believed that Phenanthrene may lead to cancer, the most common being lung cancer, and can inhibit the germination of plants. Lepidum sativum my indicator, is a plant whose germination rate is impaired by the presence of PAHs. The rate of growth of the plant is an indication of the decomposition of Phenanthrene. If the plants grew like the control, it indicates the Phenanthrene decomposed; if not it had not. After exposing the Phenanthrene contaminated soil to white and UV light, I planted Lepidum sativum in the soil and observed its germination rate. If Phenanthrene has degraded the plants will germinate at the rate of the control group, if not their germination rate will be impaired. In my study, I found that it took about four

or the Phenanthrene to break down, so that Lepidium sativum could germinate. On day three controls would germinate, but the Phenanthrene pots were still dormant. But on day four, both pots were germinating at similar rates. The effect of the soil on the photodegradation of phenanthrene was worth noting. Garden soil, and garden soil and sand mixtures germinated at a higher rate with Phenanthrene than potting mix. No matter the soil, by the end of seven days both the control and the highest levels of Phenanthrene were germinating at least 90% because the Phenanthrene had broken down.