Exposure to lead during childhood can cause permanent neurologic damage, and there is no safe level of lead in the blood. In the United States, the most common source of childhood lead exposure is lead paint, which is mainly found in old housing. Because of this, the national strategy for childhood lead exposure prevention rightly focuses on identifying children in places with old housing stock who have elevated blood lead levels (EBLLs) and remediating their homes to prevent exposure to lead.1 However, other sources of lead exposure exist. Examples include products manufactured abroad, including spices, cosmetics, toys, and other household products2; plumbing pipes and fixtures, from which lead can leach into tap water3; workplace dust/debris that can be carried home on clothing, in vehicles, or on equipment4; products manufactured domestically, including ammunition, fishing weights,5 and batteries; soil near renovated homes or near airplane runways contaminated by leaded airplane fuel; ammunition fragments consumed while eating game meat6 , 7; and several other exposure sources abroad.
Alaska's housing stock is new relative to other states. As of 2016, only 3% of existing homes in the state were built before 1950, 14% were built during 1950-1969, and 24% were built during 1970-1979; in comparison, 18%, 22%, and 16% of homes nationwide were built before 1950, during 1950-1969, and during 1970-1979, respectively.8 As such, in Alaska, other sources of childhood lead exposure may be more common.
All blood lead tests for Alaska residents are required to be reported to the Alaska Section of Epidemiology, which maintains a database of reports and conducts follow-up telephone interviews and education with parents and providers for all children with an EBLL. These data and interviews provide insight into sources of childhood lead exposure in Alaska. This review provides an analysis of the available recent data on childhood lead testing in Alaska, the possible sources of exposure, and ongoing work in Alaska to improve childhood lead surveillance and prevent childhood lead exposure.
We reviewed all venous and capillary BLL tests reported to the Alaska Section of Epidemiology during 2011-2015 for children younger than 72 months (<6 years). This time frame represents the most current and complete data available for child BLL tests in Alaska. Population numbers were derived from census estimates.15 We calculated the annual percentage of children tested and the prevalence of BLLs of 5 μg/dL or more among children tested. For children with more than 1 BLL test, only the highest confirmed BLL test result was included for analysis. Although the national reference level for an EBLL was reduced from 10 to 5 μg/dL in 2012, this analysis includes all BLLs of 5 μg/dL or more during 2011-2015 for consistency.
Although the Alaska Blood Lead Surveillance database is not yet complete for non-EBLLs (<5 μg/dL) in Alaska after 2015, follow-up telephone intervention is conducted for all elevated BLLs on a monthly basis, and these data are available through April 2018. To utilize the maximum amount of information on exposure sources, we also analyzed exposure sources for children with EBLLs during January 2016 to April 2018. This provided follow-up information for all Alaska children with an EBLL during January 2011 to April 2018. We reviewed documentation from follow-up interviews with parents and providers of all children younger than 72 months with an EBLL during this time frame and summarized the most frequently identified possible exposure sources. Because the Centers for Disease Control and Prevention reduced the definition of an EBLL in 2012 from 10 μg/dL or more to 5 μg/dL or more, follow-up calls were only conducted for BLLs of 10 μg/dL or more in 2011 but for all BLLs of 5 μg/dL or more during 2012-2018.
During follow-up telephone interviews, multiple possible lead exposure sources are identified. The form used for these follow-up calls is attached in Supplemental Digital Content Appendix A (available at http://links.lww.com/JPHMP/A529). However, because the Section of Epidemiology does not conduct on-site follow-up environmental investigations for EBLL cases, the actual, confirmed source(s) of exposure for most cases cannot be firmly established. This report and the use of Alaska Lead Surveillance Program data for this purpose are exempt from institutional review board review under exemption 4, as an analysis of existing public health surveillance data.
During 2011-2015, 4962 children younger than 72 months statewide received at least 1 blood lead test (Table 1); 495 (10%) of these children received 2 or more tests during these years. The annual number of Alaska children tested ranged from 599 in 2013 (0.9%) to 1641 in 2015 (2.6%). Of the 4962 children tested, 410 (8%) were tested at 0 to 12 months of age, 637 (13%) at 13 to 24 months of age, 561 (11%) at 25 to 36 months of age, and 3354 (68%) at 37 to 71 months of age. For children with more than 1 BLL test during these years, only the highest confirmed BLL test result and the child's age at the time of that test were included for analysis.
Among the 4962 children tested during 2011-2015, 80 (1.6%) had a BLL of 5 μg/dL or more. Of those, 54 (68%) had a BLL of 5.0 to 9.9 μg/dL, 13 (16%) had a BLL of 10.0 to 14.9 μg/dL, 13 (16%) had a BLL of 15.0 to 45.0 μg/dL, and none had a BLL of more than 45 μg/dL. Of the 29 children with a BLL of 5 μg/dL or more who received 1 or more additional tests before 72 months of age, 9 (31%) still had a BLL of 5 μg/dL or more on repeat testing.
In addition to the 80 BLLs of 5 μg/dL or more identified during 2011-2015, 74 were identified during January 2016 through April 2018, yielding a total of 154 BLLs of 5 μg/dL or more during January 2011 through April 2018. These 154 children included 14 with a BLL between 5 and 9 μg/dL in 2011 whose parents were not contacted for follow-up because these levels were not considered elevated at the time. Among the remaining 140 children with an EBLL, 74 (53%) were reached for telephone follow-up intervention.
The possible exposure sources identified during interviews for the remaining 74 children are shown in Table 2. Multiple exposure sources are possible. The most commonly indicated possible exposure sources were parent occupation (54%), consumption of game or subsistence meat hunted with lead ammunition (50%), pre-1978 housing or home renovation (39%), and pica or mouthing of nonnutritive objects (27%). Parent occupation refers to parents who work with lead or who are exposed to lead at their job or in a hobby and risk exposing their child to lead dust from its deposition on work clothing. Such occupations included work in mining, with airplanes or cars, and with firearms. Children might also be directly exposed to parents' occupational hazards if they accompany parents during these activities. Such exposures may include time spent in airplane hangars, time spent in airplane or automobile shops, or exposure to marine paint, batteries, fishing weights, or ammunition. Hence, Table 2 includes overlap between possible direct and indirect sources of lead exposure.
This review summarizes the frequency of childhood lead testing in Alaska during 2011-2015 and the most commonly identified possible sources of lead exposure among children with a BLL of 5 μg/dL or more during January 2011 through April 2018.
The proportion of children who received BLL testing in Alaska during these years was low compared with the rest of the United States. During 2011-2015, 0.9% to 2.6% of Alaska children younger than 72 months were tested annually, whereas 10.0% to 16.7% of all US children younger than 72 months were tested annually during the same years.16 This difference is explained, in part, by the fact that from 1994 until 2016, the Alaska Division of Public Health recommended targeted testing based on clinical risk assessment for all children in Alaska rather than universal testing.17 Most other states and jurisdictions have required targeted testing of specific populations or universal testing of all children. Such policies drive the national childhood testing average up.
The prevalence of EBLLs among children tested in Alaska is also low relative to the prevalence among children tested nationwide. During 2011-2015, the percentage of children tested in Alaska who had a BLL of 5 μg/dL or more ranged from 1.0% to 2.3% (with no discernable trend) whereas the percentage of children tested nationally who had a BLL of 5 μg/dL or more decreased from 6.6% to 3.3% (with a clear decreasing trend).16 The lower prevalence of EBLLs in Alaska is due, in part, to the fact that Alaska has newer housing stock than most states, which obviates the most common source of lead exposure among US children. Moreover, targeted testing of children living in old homes (as is done in other states) results in an EBLL prevalence among children tested nationally that is higher than the EBLL prevalence in nationally representative surveys such as the National Health and Nutrition Examination Survey. Finally, Alaska's former risk assessment–based screening policy was likely to have captured fewer EBLL cases than states that required universal or demographically targeted screening because of the inherent imperfection of relying on clinical risk assessment to determine whether testing is warranted.
As demonstrated in this analysis, children in Alaska are exposed to lead from many nonhousing sources. While the possible exposure sources identified through telephone interviews are useful for developing intervention strategies, in most cases, the actual source of exposure that caused a child's EBLL is not firmly established. Routine on-site environmental investigations for EBLLs, such as those conducted in other jurisdictions in the United States, would identify actual exposure sources and help characterize the risk posed by those sources. In Alaska, however, many communities are not connected to the road system and are only accessible by small airplane or by boat, and limited public health resources have thus precluded the Section of Epidemiology from conducting such investigations.
In 2016, the Alaska Division of Public Health issued new lead screening recommendations that include universal testing of all Medicaid-eligible children and risk-based testing for all other children.14 Prior to 2016, the Centers for Disease Control and Prevention guidance warranted only risk-based testing for all Alaska children because of a low EBLL prevalence in the state.9 , 18 Alaska's new lead screening recommendations assure coherence with Medicaid's Early and Periodic Screening, Diagnosis, and Treatment services, which require testing of all Medicaid-eligible children at 12 and 24 months of age or before 72 months of age if the child has not previously been tested.19 This updated policy has resulted in an increase in BLL testing and a corresponding increase in EBLLs identified since 2016.20
In addition to this policy change, the Alaska Department of Health and Social Services is engaging in further efforts to enhance lead testing in the state in order to increase EBLL detection and to better characterize exposure sources and at-risk populations. For example, the Section of Epidemiology has assembled a Lead Screening and Surveillance Workgroup consisting of local health authorities, public entities, and clinical organizations throughout the state to develop a strategy to boost testing, improve surveillance, characterize risks, and educate the public on childhood lead exposure. The Alaska Section of Public Health Nursing has also increased child lead testing with analytical support from the Alaska State Public Health Laboratory. Meanwhile, HeadStart organizations in Alaska are facilitating lead testing during enrollment. Increasing testing statewide will help the Section of Epidemiology identify more cases of EBLL, offer timely interventions, and better characterize the risk for Alaska children. The Section of Epidemiology is also conducting provider education through grand rounds, webinars, and conference presentations and producing Alaska-specific educational resources on lead exposure and prevention for the public.
Implications for Policy & Practice
- The work being done in Alaska may be helpful for other jurisdictions nationwide as they assess their current lead surveillance strategies—particularly as they pertain to exposure sources other than lead paint.
- As progress is made nationwide in eliminating lead paint as an exposure source, prevention efforts will increasingly focus on other exposure sources. Quality epidemiologic data, risk assessment, and intervention will ensure that practical, evidence-based public health action is taken to prevent childhood lead exposure.
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8. US Census Bureau. 2012-2016 American Community Survey 5-Year Estimates, Table B25034. Suitland, MD: US Census Bureau; 2017.
15. Alaska Department of Labor and Workforce Development. Alaska population by age and sex, 2010 to 2017. http://live.laborstats.alaska.gov/pop
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18. Centers for Disease Control and Prevention. Screening
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