IntroductionChildhood brain tumors, most commonly neuroblastomas, are the leading cause of cancer death in US children. Most of these brain cancers are diagnosed before 5 years of age. Besides prenatal exposure to pesticides, one of the main causes of child brain tumors is exposure to diesel exhaust [1][2][3][4][5][6][7][8]. The latest (2016) government data show that for the last 10 years, annual rates of cancer incidence have been increasing 3 times faster for children under age 15 than for adults. For the last 10 years, annual rates of brain cancer have been increasing 9 times faster for children (1.8 percent/year) than for adults (0.2 percent/year). However the brain-cancer-survival rates are not increasing [9][10][11][12].Recently three-year-old Citlalih Ramirez of East Los Angeles was diagnosed with an aggressive brain cancer, neuroblastomas. She is one of about 5,000 US infants and children diagnosed each year with brain tumors. Most children diagnosed with neuroblastomas will not see their next 5 birthdays. Because diesel exhaust is tied to brain tumors, Citlalih -like many other victims -may have been harmed by diesel exhaust in her neighborhood of East Los Angeles. It is home to the largest port complex in the US Diesel-powered ships bring goods from abroad, and national rail/trucking-hubs transport them across the US Every day 30,000-50,000large heavy-duty diesel trucks barrel through Citlalih's neighborhood. The result? The East-LA cancer rate is 19 times higher than average-US rates, and 11 times higher than already-high Los Angeles rates [13][14][15][16][17].In the US, minority communities such as East Los Angeles have the highest exposures to diesel exhaust and other air toxics, while largely-white communities have the lowest [18]. Why is the rate of child cancers increasing so much faster than that that of adults, especially in hub communities? Why are rates of relatively rare brain tumors skyrocketing, with the rate of child brain tumors increasing 9 times faster than that of adults?Children obviously are more pollution-sensitive than adults, and their detoxification mechanisms are not fully developed. Unlike adults, children also have developmental periods during which they can be permanently structurally changed, pre-programmed for later disease, death, and misdevelopment [19]. Likewise both adult and child cancer have been increasing so dramatically that genetics cannot be the major cause. Instead researchers, including those from the WHO, say "the overwhelming contribution to the causation of cancer in the population" is "the environment" [20][21][22]. But if environment is a major key to preventing escalating cancer rates, why doesn't government clean up diesel-hub areas like East Los Angeles? This article shows that apparent US regulatory reliance, on scientifically-flawed diesel-industry studies, is likely one reason for this regulatory failure.