Agriculture in the U.S. makes up approximately 75% of the country's pesticide use. Agricultural workers are at high risk for being exposed to dangerous levels of pesticides, whether or not they are directly working with the chemicals. Migrant workers, especially women, are at higher risk for health issues associated with pesticide exposure due to lack of training or appropriate safety precautions. Some U.S. research centers are focused on the topic of health and safety in agricultural practices. These centers not only conduct research on the subject of occupational disease and injury prevention, but also promote agricultural health and safety through educational outreach programs. Most of these groups are funded by the National Institute for Occupational Safety and Health, the US Department of Agriculture, or other state agencies. Centers include:  The number of women working in agriculture has risen and the 2002 census of agriculture recorded a 40% increase in the number of female farm workers. Inequality and respect are common issues for these workers, as many have reported that they are not being respected, listened to, or taken seriously due to traditional views of women as housewives and caretakers. Women may also face resistance when attempting to advance to higher positions. Other issues reported by female farm workers include receiving less pay than their male counterparts and a refusal or reluctance by their employers to offer their female workers the same additional benefits given to male workers such as housing. Historically, farmland has been owned by small property owners, but as of 2017 institutional investors, including foreign corporations, had been purchasing farmland. In 2013 the largest producer of pork, Smithfield Foods was bought by a company from China. As of 2017, only about 4% of farms have sales over $1m, but these farms yield two-thirds of total output. Some of these are large farms have grown organically from private family-owned businesses. As of 2019, six states—Hawaii, Iowa, Minnesota, Mississippi, North Dakota, and Oklahoma—have laws banning foreign ownership of farmland. Missouri, Ohio, and Oklahoma are looking to introduce bills banning foreign ownership as of 2019. The state with the most foreign ownership as of 2019 is Maine, which has 3.1 million acres that are foreign-controlled, followed closely by Texas at 3 million acres. Alabama, at 1.6 million acres, Washington, at 1.5 million acres, and Michigan, at 1.3 million acres, round out the top five, according to the Midwest Center’s analysis.