Surgical gloves are usually sized more precisely since they are worn for a much longer period of time and require exceptional dexterity. The sizing of surgical gloves are based on the measured circumference around the palm in inches, at a level slightly above the thumb's sewn. Typical sizing ranges from 5.5 to 9.0 at an increment of 0.5. Some brands may also offer size 5.0 which is particularly relevant to women practitioners. First-time users of surgical gloves may take some time to find the right size and brand that suit their hand geometry the most. People with a thicker palm may need a size larger than the measurement and vice versa. Research on a group of American surgeons found that the most common surgical glove size for men is 7.0, followed by 6.5; and for women 6.0 followed by 5.5. To facilitate donning of gloves, powders have been used as lubricants. Early powders derived from pines or club moss were found to be toxic. Talcum powder was used for decades but linked to postoperative granuloma and scar formation. Corn starch, another agent used as lubricant, was also found to have potential side effects such as inflammatory reactions and granuloma and scar formation. With the availability of non-powdered medical gloves that were easy to don, calls for the elimination of powdered gloves became louder. By 2016, healthcare systems in Germany and the United Kingdom had eliminated their use. In March 2016, the United States Food and Drug Administration (FDA) issued a proposal to ban their medical use and on December 19, 2016 passed a rule banning all powdered gloves intended for medical use. The rule became effective on January 18, 2017. Powder-free medical gloves are used in medical cleanroom environments, where the need for cleanliness is often similar to that in a sensitive medical environment. To make them easier to don without the use of powder, gloves can be treated with chlorine. Chlorination affects some of the beneficial properties of latex, but also reduces the quantity of allergenic latex proteins. Due to the increasing rate of latex allergy among health professionals, and in the general population, gloves made of non-latex materials such as polyvinyl chloride, nitrile rubber, or neoprene have become widely used. Chemical processes may be employed to reduce the amount of antigenic protein in Hevea latex, resulting in alternative natural-rubber-based materials such Vytex Natural Rubber Latex. However, non-latex gloves have not yet replaced latex gloves in surgical procedures, as gloves made of alternative materials generally do not fully match the fine control or greater sensitivity to touch available with latex surgical gloves.