Int. J. Environ. Res. Public Health 2018, 15, 2149
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America [5]. The estimated pooled odds ratio (OR) of lung cancer increased with radon concentration
monotonically [5]. Analysis from thirteen case-control studies conducted in nine European countries
between 1982–1995 also showed appreciable hazards from residential radon exposure, responsible for
an estimated 2% of all deaths from cancer in Europe [6]. The risk of lung cancer increased by 8.4% per
100 Bq/m 3 (~2.7 pCi/L) increase in measured radon [6]. These residential studies provide evidence of a
positive association between residential radon exposure and lung cancer risk [7]. Currently, the World
Health Organization (WHO) and the United States Environmental Protection Agency (USEPA) both
classify radon as a leading causes of lung cancer, second only to smoking.
Radon exposure at schools may have a considerable public health impact. It was estimated that
approximately 14% of the 300,000 annual lung cancer cases in the United States are attributable to
radon [8]. The risk of lung cancer in children resulting from exposure to radon may be up to three-
fold higher than that of adults exposed to the same amount of radon [9] due to the morphometric
differences between the lungs of children and the lungs of adults [10], as well as higher respiration
rates of children compared with adults. Children also spend more time indoors, and are generally
more sensitive to environmental hazards exposure [11]. It was estimated that U.S. children, on average,
spend 6.64 h per day for 180 days per year in school buildings [12]. This does not include the substantial
additional hours that children might spend in school buildings in after-school programs. Schools are
also workplaces for teachers and administrators and service staff, who might spend even more time
than children in school buildings. In the late 1980s, short-term radon measurements were conducted
in 3000 rooms in 130 U.S. schools in 16 states [13]. Over half of the schools had at least one room with
radon levels above 4 pCi/L, and all 16 tested states had some classrooms with radon above 4 pCi/L,
with the highest classroom showing 136.2 pCi/L. Therefore, high levels of radon in school buildings
may pose significant health risks to those who spend many months, or years, at those schools [14].
Given the lack of U.S. Federal regulations concerning radon levels in schools, we reviewed
specific state statutes on radon that could influence exposure to school children, including bills that
passed in the 2017 U.S. legislative sessions. We further discuss Federal and state regulations as they
relate to radon reduction and control, radon testing, dissemination of radon levels to the public,
radon mitigation, and various challenges and policy recommendations.
2. Radon Reduction and Control: Federal Laws and Efforts
Radon exposure has not been linked with major diseases in childhood, but the risk of greatest
concern is that of consequent lung cancer in adulthood. The USEPA’s risk estimates for radon are
based on cohort studies of male workers in mines [7,15]; however, the derived risk estimates were
erroneously extrapolated to women, children, and non-working men. Cao and associates recently
re-analyzed cohort studies of male workers in mines, and the results show that the USEPA’s original
estimates of fatal risks attributable to radon may be overestimated by 9–26% after accounting for
confounding by occupational exposure to diesel. Although methods for estimating risks have changed
over the years, the observed risks attributable to radon are still considered to be unacceptable [7],
and radon exposure maintains its high public health importance as the second leading cause of lung
cancer deaths in the U.S. Whereas European Union (EU) regulations regarding radon are discussed
briefly in a separate section below, we note here that the influence of EU directives on radon exposure
in EU member countries may have relevance to the role U.S. Federal agencies, such as the USEPA,
may play in reducing exposure in individual U.S. states [16].
The Superfund Amendments and Reauthorization Act (SARA) of 1986 requires USEPA to (1)
conduct nationwide assessments of radon gas across the United States where people live, work, and go
to school; (2) assess the levels of radon gas present in such structures and the impact to human health;
and (3) determine methods of reducing or eliminating human exposure to radon gas and provide
guidance and public information materials based on the results of those assessments (SARA, Title I,
Section 118(k) (1)). SARA further requires the USEPA to (1) establish a research program to facilitate the
understanding of health problems associated with exposure to air pollutants including radon gas in the