Atopy is a predisposition toward developing certain allergic hypersensitivity reactions. Atopy may have a hereditary component, although contact with the allergen or irritant must occur before the hypersensitivity reaction can develop.
As of 2012, 63.9 percent of players playing in Major League Baseball are white. There is no way of telling the exact number due to the number of players.
In 2006, an investigation produced the Mitchell Report, which implicated many players in the use of performance-enhancing substances, including at least one player from each team. Today, MLB is composed of thirty teams: twenty-nine in the United States and one in Canada.