What designator after the letters TLV indicates that direct or airborne contact with a substance could result in possible and significant exposure?

The designation "Skin" following the TLV letters indicates that direct or airborne contact with a substance could lead to considerable and significant exposure through the skin. This designation is crucial for understanding the potential routes of exposure, particularly for substances that can be absorbed through the skin and may have harmful effects. For example, some chemicals might not only pose a risk through inhalation but also through dermal contact, which could result in systemic toxicity or local effects at the site of contact.

In occupational health and safety contexts, recognizing this risk is vital for ensuring the safety and well-being of individuals working with hazardous substances, as it highlights the necessity for protective measures beyond respiratory protection, such as using gloves or protective clothing.