performing employees and better realize our investment in training new employees. Failure to do so will adversely impact our operating results by increasing training costs and making it more difficult to deliver outstanding customer experiences. Our failure to find and keep enough high-caliber employees could also delay planned restaurant openings, which would slow our growth.
We use the “E-Verify” program, an Internet-based, free program run by the U.S. government, to verify employment eligibility for all employees throughout our company. However, use of E-Verify does not guarantee that we will successfully identify all applicants who are ineligible for employment. Although we use E-Verify and require all workers to provide us with government-specified documentation evidencing their employment eligibility, some of our employees may, without our knowledge, be unauthorized workers. Unauthorized workers may subject us to fines or penalties, and if we are found to be employing unauthorized workers, we could experience adverse publicity that negatively impacts our brand and may make it more difficult to hire and keep qualified employees. For example, following an audit by the Department of Homeland Security of the work authorization documents of our restaurant employees in Minnesota during 2010, we lost approximately 450 employees, resulting in a temporary increase in labor costs and disruption of our operations, including slower throughput, as we trained new employees, as well as some degree of negative publicity. The resulting broad-based civil and criminal investigations by the U.S. Attorney for the District of Columbia and U.S. Securities and Exchange Commission of our compliance with work authorization requirements and related disclosures and statements resulted in significant legal costs. Termination of a significant number of employees in specific markets or across our company due to work authorization or other regulatory issues would disrupt our operations including slowing our throughput, and could also cause additional adverse publicity and temporary increases in our labor costs as we train new employees. We could also become subject to fines, penalties and other costs related to claims that we did not fully comply with all recordkeeping obligations of federal and state immigration compliance laws. Our reputation and financial performance may be materially harmed as a result of any of these factors. Furthermore, immigration laws have been an area of considerable political focus in recent years, and the U.S. Congress and Department of Homeland Security from time to time consider or implement changes to Federal immigration laws, regulations or enforcement programs. Further changes in immigration or work authorization laws may increase our obligations for compliance and oversight, which could subject us to additional costs and potential liability and make our hiring process more cumbersome, or reduce the availability of potential employees.
Because we do not franchise, risks associated with hiring and maintaining a large workforce, including increases in wage rates or the cost of employee benefits, compliance with laws and regulations related to the hiring, payment and termination of employees, and employee-related litigation, may be more pronounced for us than for restaurant companies at which some or all of these risks are borne by franchisees or other operating contractors.
Changes in food and supply costs could adversely affect our results of operations.
Our profitability depends in part on our ability to anticipate and react to changes in food and supply costs. Like all restaurant companies, we are susceptible to increases in food costs as a result of factors beyond our control, such as general economic conditions, seasonal fluctuations, weather conditions, global demand, food safety concerns, generalized infectious diseases, fluctuations of the U.S. dollar, product recalls and government regulations. The cost of many basic foods for humans and animals, including corn, wheat, rice and cooking oils, has increased markedly in some years, resulting in upward pricing pressures on almost all of our raw ingredients including chicken, beef, tortillas and rice. In 2017, a significant rise in avocado prices adversely impacted our food costs for most of the year, and there could be similar or greater pricing pressure on key ingredients in future periods. Costs have also increased from the enhanced food safety procedures described elsewhere in this report. Additionally, a substantial volume of produce items are grown in Mexico and other countries, and some of our meats and restaurant supplies are sourced from outside the U.S. as well. Any new or increased import duties, tariffs or taxes, or other changes in U.S. trade or tax policy, could result in higher food and supply costs that would adversely impact our financial results.
We could also be adversely impacted by price increases specific to meats raised in accordance with our sustainability and animal welfare criteria or other food items we buy as part of our Food With Integrity focus, the markets for which are generally smaller and more concentrated than the markets for food products that are conventionally raised and grown. Weather related issues, such as freezes or drought, may also lead to temporary spikes in the prices of some ingredients such as produce or meats. Increasing weather volatility or other long-term changes in global weather patterns, including any changes associated with global climate change, could have a significant impact on the price or availability of some of our ingredients. Any increase in the prices of the ingredients most critical to our menu, such as chicken, beef, cheese, avocados, beans, rice, tomatoes and pork, would have a particularly adverse effect on our operating results. Alternatively, in the event of cost increases with respect to one or more of our raw ingredients, we may choose to temporarily suspend serving menu items, such as guacamole or one or more of our salsas, rather than paying the increased cost for the ingredients. Any such changes to our available menu may negatively impact our restaurant traffic and comparable restaurant sales, and could also have an adverse impact on our brand.