Most raw materials aren't grown in every color so yarn is dyed, often with harsh chemicals, to make colored materials. On their own, many of these chemicals are known to possess carcinogenic properties and/or be disruptive to human endocrine (reproductive) systems. Then fabrics are made into clothes which sit against our skin, the largest and organ in our bodies. It hasn't (and many argue can't) be proven that wearing these clothes cause any health issues, but the Standard 100 certifies this product is harmless to human health. Every single component and accessory is tested by an accredited lab, before final products can earn this certification - textile, zippers, buttons, threads, prints, and all. Standard 100 is owned and managed by OEKO-TEX® which consists of 17 independent textile and leather testing institutes in Europe and Japan, with offices in more than 70 countries.