Which of the following is NOT a cause of nail disorders?

Overhydration is not typically recognized as a direct cause of nail disorders. Nail disorders can arise from various underlying factors, such as hereditary conditions, which can influence nail growth and appearance due to genetic predisposition. Injury can also result in nail damage or abnormalities, as physical trauma can disrupt the normal growth patterns of nails. Additionally, excessive hand washing can lead to dry, brittle nails or other nail issues, making it a potential cause of nail disorders as well.

In this context, while overhydration can affect other aspects of nail health, it does not directly lead to the same range of nail disorders caused by the factors mentioned. Therefore, it is the correct answer in identifying something that is not typically classified as a cause of nail disorders.