Which statement is true regarding seals for packaging materials?

The correct answer is that seals for packaging materials must not unexpectedly open in storage. This is crucial for maintaining the integrity and sterility of the contents inside the packaging, particularly in medical and surgical settings where contamination can pose significant risks. A secure seal helps ensure that the items remain protected against environmental factors, such as moisture and airborne contaminants, and reduces the risk of accidental exposure or loss of sterility.

In scenarios where seals unexpectedly open, the packaging is compromised, leading to potential hazards. Therefore, it is vital that the seals are designed to remain intact during storage, providing assurance that the materials will remain in a safe and usable condition until they are needed.

In contrast, the other statements suggest characteristics that would not necessarily adhere to the standards required for packaging materials. For instance, while a seal that peels off may lead to concerns about storage integrity, transparency in seals can depend on specific regulations and contexts. Similarly, while some seals may be made of paper, it's not a strict requirement nor does it imply anything about the effectiveness of the seal in protecting its contents.