Which of the following statements regarding nicotine is accurate?

Nicotine is a substance found in tobacco products that plays a significant role in addiction, but it is not directly linked to an increased risk of cancer in the same way that other harmful chemicals found in tobacco smoke are. However, it is important to recognize that nicotine can contribute to the cancer risk indirectly. For example, nicotine is a highly addictive stimulant, which can lead to prolonged use of tobacco products that contain various carcinogenic chemicals. The more someone uses tobacco products, the higher their exposure to these harmful substances, thereby increasing their cancer risk.

In the context of the other options, stating that nicotine is non-addictive does not accurately reflect the strong dependence it can create. Additionally, while nicotine is known to increase heart rate, it can lead to long-term cardiovascular issues. Lastly, nicotine is indeed present in many e-cigarettes, making the claim that it is not found in them inaccurate. This highlights the prevalence of nicotine across a variety of smoking practices and products, solidifying its role in health risks associated with tobacco and its substitutes.