this association was positive for people in the age group 35–44 years ( OR = 4.006, 95% CI [2.478, 6.477]) and the age group 45–54 years ( OR = 2.623, 95% CI [1.513, 4.546]). The three logistic regression models were used to calculate the change in total log-odds of having a BLL >0.76 μg/dl per one unit increase in poverty-income ratio (Table 6). For the first, unadjusted model, one unit increase in the poverty-income ratio resulted in an insignificant change in total log-odds of BLL >0.76 μg/dl ( p = .8480). Model 2 produced a significant estimate of change in total log-odds (estimate: -0.1748, p < .0001). Lastly, model 3 had similar, but less pronounced, results (esti- mate: -0.126, p = .0047). Finally, stratified analysis by age group was performed using the fully adjusted model to calculate the change in total log-odds of hav- ing a BLL >0.76 μg/dl per one unit increase in poverty-income ratio (Table 7). This mod- eling produced significant results only for individuals in the age group 35–44 years (estimate: -0.3826, p = .0002) and age group 45–54 years (estimate: -0.2953, p = .0002). Discussion The present study sought to examine the prev- alence of BLLs >0.76 μg/dl sample median level in the U.S. population and investigate demo- graphic factors associated with higher BLLs in 2017–2018. The results of this analysis showed that approximately 50% of people in the U.S. had BLLs >0.76 μg/dl in 2017–2018 (which is expected, given that 0.76 μg/dl represents the sample median), with significant dier- ences demonstrated when considering race, age group, gender, and 100-cigarette history. Specifically, non-Hispanic Blacks and Mexi- can Americans, individuals 60–79 years and ≥80 years, males, and individuals with a his- tory of smoking ≥100 cigarettes had a higher prevalence of elevated BLLs compared with their respective counterparts. The dierences in mean BLL within each demographic group revealed that in 2017–2018, people in the U.S. ≥80 years of age, individuals identifying as Other Race, males, individuals living in pov- erty, and individuals with a lifetime history of smoking ≥100 cigarettes had the highest BLLs in their respective demographic groupings. While unadjusted logistic regression model- ing did not reveal any significant association, both adjusted models 2 and 3 showed that individuals living in or near poverty had sig-
TABLE 3
Weighted Distribution of Blood Lead Level (BLL) Less and Greater Than 0.76 μg/dl by Demographic From the 2017–2018 National Health and Nutrition Examination Survey
Demographic
% BLL <0.76 μg/dl
% BLL >0.76 μg/dl
p -Value a
Total
50.26
49.74
Age (years)
<.0001
>18
85.81 79.54 64.37 59.14 50.11 23.56 19.99 14.04 60.74 66.89 50.24 53.93 43.31
14.19 20.46 35.63 40.86 49.89 76.44 80.01 85.96 39.26 33.11 49.76 46.07 56.69
18–24 25–34 35–44 45–54 55–64 65–80
>80
Race
.0003
Mexican American
Other Hispanic
Non-Hispanic White Non-Hispanic Black
Other
Gender
<.0001
Male
64.57 70.88
35.43 29.12
Female
Poverty status
.4228
In poverty
52.63 48.98 53.01
47.37 51.02 46.99
Near poverty Not in poverty
Smoking history b
<.0001
Yes
34.98 54.15
65.02 45.85
No
a Wald chi-square p -value. b Lifetime history of smoking ≥100 cigarettes.
viduals in poverty was 0.985 (95% CI [0.740, 1.311], p = .9120). The first adjusted logis- tic regression model resulted in significantly positive odds ratios for individuals near pov- erty ( OR = 1.926, 95% CI [1.622, 2.287], p < .0001) and for individuals in poverty ( OR = 1.973, 95% CI [1.497, 2.599], p < .0001). The second adjusted model produced similar significant results for individuals near pov- erty ( OR = 1.744, 95% CI [1.388, 2.190], p = .0001) and for individuals in poverty ( OR = 1.824, 95% CI [1.324, 2.513], p = .0012).
The fully adjusted logistic regression model was repeated with stratification for age group (Table 5). This stratification resulted in many insignificant age-specific associations between poverty status and BLL. In this modeling, sta- tistics and odds ratios for the age group <18 years were not reported due to missing or non- positive weights. Stratification by age group for individuals living near poverty resulted in positive odds ratios for people only in the age group 35–44 years ( OR = 3.216, 95% CI [1.830, 5.652]). For individuals in poverty,
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