nuclear plants have further been questioned as a source of the cases due to comparison to the Savannah River Site in the United States. Despite release of radiation at the Savannah River Site, there is no increase in cases of leukemia around it. Alternative hypotheses for the cause of the cases have included electromagnetic fields, parental radiation exposure prior to conception, other carcinogens, and benzene exposure; however, none have been supported by the existing evidence. Intriguingly, a larger case-control study in Lower Saxony found a correlation between the "untrained immune system" (as judged as contact with other children, vaccinations, etc.) and leukemia risk, suggested that an immature immune system that has not been challenged is at greater risk for developing malignancy, possibly secondary to an undetermined environment factor. Tourism Located between the North Sea and the Baltic Sea, Schleswig-Holstein is also a popular tourist destination in Germany. Its islands, beaches and cities attract millions of tourists every year. It has the second highest tourism intensity per local among the German states, after Mecklenburg-Vorpommern, but in absolute value it is rank 6th and only 1/3 of top destination Bavaria. According to a ruling by the Federal Administrative Court, everyone has the right to free access to the beach. Nevertheless, most of the seaside resorts kept cashing in (2-€3 /day/person). Agriculture 63% of land in Schleswig-Holstein (990 403 ha) is used for agriculture (national average 47%). Cultivated crops: Wheat, 208 000 ha Maize for silage, 176 000 ha Winter rapeseed, 112 000 ha Sugar beet, 7 500 ha Potatoes, 5 500 ha There are some special cultivation regions: Elbmarschen, west of Hamburg for fruits cultivation Ditmarschen for cabbage Between Mölln and Lübeck for asparagus Pinnenberg for tree nurseries and flower garden (especially, roses of Rosen Tantau and W. Kordes' Söhne), 2 931 ha. These 2 companies have over 50% of the world cut roses market. There is a German Nurseries Museum ("Deutsches Baumschulmuseum"). Animal husbandry The dairy and cattle farming in connection with fodder cultivation is mainly concentrated on the marshland and the bordering Geest areas. In 2020, around 1 million cattle including 360,000 dairy cows were counted in Schleswig-Holstein, rank 4th of German states. Livestock is continuously declining. Schleswig-Holstein is home of the most productive dairy cattle: Holsteins, which produce an average of per year of milk. It is now the main dairy cow around the world. Pig breeding is mainly