Small-scale farmers are also having a difficult time complying with private standards, which are often dictated by supermarket firms. These standards can spell out any number of things, such as what methods of production to use, storage requirements, and even how something ought to look. Most of the certifying organizations that oversee compliance to these standards are located in affluent nations. Primus Labs in the USA, for instance, certifies for 68 percent of the fruit and vegetable firms in northwest Mexico(Narrod et al. 2008: 361). The costs of certification can therefore present insurmountable barriers for small-scale growers looking to raise nontraditional commodities for export(certification is discussed in greater length in Chapter 12). According to one estimate, costs of certification can be as high as US$850 per hour(Narrod et al. 2008: 361).