Assessing human metal accumulations in an urban superfund site

Abstract

Butte, Montana is part of the largest superfund site in the continental United States. Open-pit mining continues in close proximity to Butte's urban population. This study seeks to establish baseline metal concentrations in the hair and blood of individuals living in Butte, MT and possible routes of exposure. Volunteers from Butte (n=116) and Bozeman (n=86) were recruited to submit hair and blood samples and asked to complete a lifestyle survey. Elemental analysis of hair and blood samples was performed by ICP-MS. Three air monitors were stationed in Butte to collect particulate and filters were analyzed by ICP-MS. Soil samples from the yards of Butte volunteers were quantified by ICP-MS. Hair analysis revealed concentrations of Al, As, Cd, Cu, Mn, Mo, and U to be statistically elevated in Butte's population. Blood analysis revealed that the concentration of As was also statistically elevated in the Butte population. Multiple regression analysis was performed for the elements As, Cu, and Mn for hair and blood samples. Soil samples revealed detectable levels of As, Pb, Cu, Mn, and Cd, with As and Cu levels being higher than expected in some of the samples. Air sampling revealed consistently elevated As and Mn levels in the larger particulate sampled as compared to average U.S. ambient air data.

Keywords: Exposure assessment; Metal mixtures; Metals; Superfund.

Figure 1

Butte, MT study area wherein soil (blue squares) and air (green circles) samples were collected. Soil samples were collected once and air samples were collected weekly during the period of May – October 2015. Weather information collected at Bert Mooney Airport weather station (yellow triangle).

Figure 2

Volunteer Demographics. Age, gender, body mass index, and smoking status information was collected from each volunteer and results are displayed as comparisons between locations (Butte vs. Bozeman). Body mass index measurements were not obtained for 10 individuals (Butte = 6, Bozeman = 4).

Figure 3

Box and whisker plots for Mn, Cu, and As concentrations found in hair samples (n=116 Butte, n=86 Control) as well as Mn, and Cu values from blood samples (n=81 Butte, n=72 Control) between the two volunteer populations.

Figure 4

Air particulate data over an 18 week period. Three air monitors, two monitoring for total suspended particulate and one PM 10µm, were placed in two locations in Butte. Air filters were changed weekly and analyzed by ICP-MS for 11 elements. Arsenic and manganese concentrations are shown in comparison to typical national average (dashed line) (ATSDR, 2007; Chen and Lippman, 2009; ATSDR, 2012).