Strict employment protection rules are also likely to encourage the use of forms of employment that are not subject to these regulations or lead to lack of enforcement of the rules. Concerning youth employment, Cazes and Tonin (2010) find that the decline in the average job tenure of young workers (15-24) in the European Union between 1999 and 2006 is associated with weaker employment protection provided by law and trade unions. Their results suggest that young workers are particularly exposed to more unstable labour markets through the risk of job loss and dismissal (as captured by the EPL index for regular contracts), whereas legislation on hiring (EPL index for temporary contracts) does not seem to have a significant impact.