Persons born between 1945 and 1965 have often had a poorer health record than the generation just preceding. More local health departments are now compiling county-specific data on birth weights. Unfortunately, the National Cancer Institute's study of cancer in counties near nuclear plants stops in 1984, leaving the story of the youngest generation of Americans an incomplete one. Any assessment of possible effects of radiation exposure on children must include cancer. In the last half century, advances in diagnosis and treatment have lowered childhood cancer mortality rates considerably, despite the growing number of cases. Another health problem plaguing society in the 1980s and 1990s that has affected the youngest group of Americans is the growing presence of asthma. One condition associated with radiation exposure is hypothyroidism, or underactive thyroid gland, due to inadequate levels of circulating thyroid hormone. Although fatalities from this disease often involve the elderly, septicemia also kills 400 US children under 15 each year.