A/HRC/28/68/Add.3 the Special Rapporteur received complaints of poor food and delayed or incomplete medical care. 71. The Special Rapporteur found the situation in the Monterrey centre particularly worrying. Minors, especially boys, spend over 22 hours a day in their cells and can use the toilets only when authorized. Minors of both sexes agreed that the behaviour of security staff is high-handed and disrespectful and said that they have less than an hour a week for outdoor physical activities. The Special Rapporteur was told that minors are often forced to do strenuous physical exercises as a form of punishment or placed in solitary confinement for extended periods, sometimes handcuffed and naked, in cells where conditions are unacceptable. Girls have been left handcuffed to toilets or washbasins for several days as a punishment. E. Migrants 72. Because of its location, Mexico is one of the main countries of origin, destination, transit and return of migrants. Migrants are extremely vulnerable to acts of violence by private individuals. The Special Rapporteur is concerned about the impunity that usually surrounds such crimes and the information he received that public employees collude in or tolerate such practices. Moreover, migrant arrests by public employees tend to be violent and accompanied by insults, threats and humiliation. 73. The conditions observed at the Siglo XXI migrant holding centre in Tapachula (Chiapas) are generally adequate for short periods of detention. However, detainees who lodge appeals generally spend long periods in detention. The Government should restrict the use of detention to exceptional cases, improve conditions of detention and avoid prolonged periods of detention. Unaccompanied boys are housed in the holding centre, while unaccompanied girls are taken to public and private hostels where conditions are generally poor and there is no proper supervision to detect trafficking and identify needs. The Special Rapporteur notes that, while he received no complaints or ill-treatment or torture at the Siglo XXI centre, he did receive complaints about incidents at several of the country’s migrant holding centres, in which migrants were insulted, threatened, humiliated and beaten. The Special Rapporteur is concerned that lawyers and civil society organizations have limited access to holding centres to monitor and assist migrants. F. Persons with disabilities 74. Most persons with disabilities who are in the prison system are not in centres reserved for their proper treatment, but are housed in confined areas of prisons characterized by insanitary conditions and overcrowding, a problem that is compounded by their health needs. Detention centres do not have the facilities, resources or trained staff to provide decent treatment and the necessary medical and psychological care to persons with disabilities, who spend almost the entire day locked up, sometimes in isolation and in harsh conditions. The conditions observed in the psychiatric wings of the Topo Chico, La Mesa and Nezahualcóyotl Bordo prisons constitute cruel, inhuman or degrading treatment. 75. Conditions at the National Psychiatric Institute are excellent. However, the Special Rapporteur received credible information about poor conditions at other public and private psychiatric centres, including poor hygiene, insanitary conditions, substandard medical care, the use of prolonged restraints, and treatments or internments that do not meet international standards of informed consent. The Special Rapporteur draws the Government’s urgent attention to the deplorable conditions at the Social Assistance and Integration Centre that he visited in the Federal District. Despite the admirable work being GE.14-25288 17