Characterization of bone aluminum, a potential biomarker of cumulative exposure, within an occupational population from Zunyi, China.

2020-01-07

OBJECTIVES:

Aluminum (Al) is a neurotoxicant; however, efforts to understand Al toxicity are limited by the lack of a quantitative biomarker of cumulative exposure. Bone Al measurements may address this need. Here, we describe and compare non-invasive bone Al measurements with fingernail Al and Al cumulative exposure indices (CEIs).

METHODS:

We completed a cross-sectional study of 43 factory workers in Zunyi, China. Bone Al measurements were taken with a compact in-vivo neutron activation analysis system (IVNAA). Fingernail samples were analyzed using inductively coupled plasma mass spectrometry. CEIs, based on self-reported work history and prior literature, were calculated for the prior 5, 10, 15, 20?years and lifetime work history. Linear regressions adjusted for age and education compared fingernail Al and Al CEIs with bone Al.

RESULTS:

Median (interquartile range (IQR)) Al measurements were: 15??g/g dry bone (IQR?=?28) for bone Al; 34.9??g/g (43.3) for fingernail; and 24 (20) for lifetime CEI. In adjusted regression models, an increase in 15-year CEI was significantly associated with increased bone Al (??=?0.91, 95% confidence interval (CI): 0.16, 1.66). Associations of bone Al with 10- and 20-year CEI were approaching statistical significance (??=?0.98, 95% CI: -0.14, 2.1; ??=?0.59, 95% CI: -0.01, 1.18, respectively). Other models were not statistically significant.

CONCLUSIONS:

Bone Al was significantly associated with 15-year Al CEI, but not other Al CEIs or fingernail Al. Bone Al may be a useful measure of cumulative, rather than short-term, Al exposure. Additional refinement of this method is ongoing.

~tOccupational and dietary differences in hydroxylated and methoxylated PBDEs and metals in plasma from Puget Sound, Washington, USA region volunteers.

Electronic waste (E-waste) recycling is a rapidly growing occupation in the USA with the potential for elevated exposure to flame retardants and metals associated with electronic devices. We previously measured polybrominateddiphenyl ethers (PBDEs) in plasma from E-waste workers and found them similar to non-E-waste workers. This study focused on structurally related PBDE derivatives, the hydroxylated (OH-PBDEs) and methoxylated (MeO-PBDEs) forms along with metals known to occur in E-waste. Humans can metabolize PBDEs and some MeO-PBDEs into OH-PBDEs, which is a concern due to greater health risks associated with OH-PBDEs. We measured 32 different OH-PBDEs and MeO-PBDEs in plasma samples provided by 113 volunteers living in the greater Puget Sound region of Washington State, USA. We measured 14 metals in a subset of 10 E-waste and 10 non-E-waste volunteers. Volunteers were selected based on occupational and dietary habits: work outdoors and consume above average amounts of seafood (outdoor), electronic waste recycling (E-waste) or non-specific indoor occupations (indoor). A two-week food consumption diary was obtained from each volunteer prior to blood sampling. OH-PBDEs were detected in all volunteers varying between 0.27 and 102 ng/g/g-lipid. The MeO-PBDEs were detected in most, but not all volunteers varying between n.d. – 60.4 ng/g/g-lipid. E-waste recyclers had OH-PBDE and MeO-PBDE plasma levels that were similar to the indoor group. The outdoor group had significantly higher levels of MeO-PBDEs, but not OH-PBDEs. Comparison of plasma concentrations of BDE-47 with its known hydroxylated metabolites suggested OH-PBDE levels were likely determined by biotransformation and at least two subpopulations identified differing in their apparent rates of OH-PBDE formation. The metals analysis indicated no significant differences between E-waste workers and non-E-waste workers. Our results indicate E-waste workers do not have elevated plasma levels of these contaminants relative to non-E-waste workers.

Authors: Hasan Z, Rolle-McFarland D, Liu Y, Zhou J, Mostafaei F, Li Y, Fan Q, Zhou Y, Zheng W, Nie LH, Wells EM
; Full Source: Journal of trace elements in medicine and biology : organ of the Society for Minerals and Trace Elements (GMS). 2020 Jan 14;59:126469. doi: 10.1016/j.jtemb.2020.126469. [Epub ahead of print]
; Authors: Schultz IR, Kuo LJ, Cullinan V, Cade S
; Full Source: The Science of the total environment. 2020 Jan 7;714:136566. doi: 10.1016/j.scitotenv.2020.136566. [Epub ahead of print]