Research has proven that heavily smoky or burnt tea, similar to other charred foods, can easily produce "3,4-Benzopyrene," a carcinogen. Accumulation of this substance in the body may lead to cell mutation and increase the risk of cancer. Therefore, severely smoky or burnt tea should not be consumed. Generally, slightly smoky tea, after being stored for a period, will see its smoky odor automatically disappear or diminish. If testing shows that the content of "3,4-Benzopyrene" is within the permissible limits for food, drinking such tea will not pose a health hazard.

Tea leaves are highly susceptible to moisture, and moldy tea leaves must not be consumed. Some may find it a pity to discard them and attempt to sun-dry them briefly before brewing, which is very dangerous. This is because moldy tea leaves harbor many harmful molds that secrete toxins detrimental to human health. Drinking such tea can often cause symptoms like腹痛, diarrhea, and dizziness. In severe cases, it may affect internal organs and trigger certain diseases. Therefore, one should never risk major harm for minor gain.

Special attention should be paid to the fact that some very tender tea leaves, such as Biluochun and Maofeng, are often covered with fine white hairs (silver fuzz). This is a sign of normal, excellent quality and should not be mistaken for "mold" on the tea leaves.