History of Inuit Community Exposure to Lead, Cadmium, and Mercury in Sewage Lake Sediments

Abstract

Exposure to lead, cadmium, and mercury is known to be high in many arctic Inuit communities. These metals are emitted from industrial and urban sources, are distributed by long-range atmospheric transport to remote regions, and are found in Inuit country foods. Current community exposure to these metals can be measured in food, but feces and urine are also excellent indicators of total exposure from ingestion and inhalation because a high percentage of each metal is excreted. Bulk domestic sewage or its residue in a waste treatment system is a good substitute measure. Domestic waste treatment systems that accumulate metals in sediment provide an accurate historical record of changes in ingestion or inhalation. We collected sediment cores from an arctic lake used for facultative domestic sewage treatment to identify the history of community exposure to Pb, Cd, and Hg. Cores were dated and fluxes were measured for each metal. A nearby lake was sampled to measure combined background and atmospheric inputs, which were subtracted from sewage lake data. Pb, Cd, and Hg inputs from sewage grew rapidly after the onset of waste disposal in the late 1960s and exceeded the rate of population growth in the contributing community from 1970 to 1990. The daily per-person Pb input in 1990 (720,000 ng/person per day) exceeded the tolerable daily intake level. The Cd input (48,000 ng/person per day) and Hg input (19,000 ng/person per day) were below the respective TDI levels at the time.

Delayed response of diatom assemblages to sewage inputs in an Arctic lake

“…High primary production is also reflected in the surface sediments of Annak Lake, which consist primarily of undecomposed algal cells, and show an organic content of~70 % ( Fig. 5; Hermanson, 1998;Hermanson and Brozowski, 2005). Aerial photos taken before and after sewage inputs also demonstrate the eutrophic condition of Annak Lake.…”

“…Our diatom analyses were performed on sub-samples from the same sediment core described in Hermanson (1998) and Hermanson and Brozowski (2005), collected from Annak Lake in August 1993. Briefly, sediment cores were collected from the deepest portion of the lake by pushing a 6.7 cm diameter polybutyrate tube with a valve affixed to the top into the sediments.…”

“…The organic matter content of the sediments was estimated by percent mass loss-on-ignition (LOI) at 550 8C (Hermanson, 1998). Sedimentary Pb and Cd were measured using graphite furnace atomic absorption spectrophotometry (AAS) while Hg was measured using manual cold vapor AAS, as described in Hermanson and Brozowski (2005). Sediments were prepared for siliceous microfossil analyses by oxidizing organic matter with 30 % hydrogen peroxide, followed by repeated rinsing with distilled water until neutral pH was achieved (Battarbee et al, 2001).…”

“…Recently, Hermanson (1991Hermanson ( , 1998 and Hermanson and Brozowski (2005) studied the geochemical and pollution history of Annak Lake (Fig. 1), a culturally eutrophied lake located on the Belcher Islands (Nunavut, Arctic Canada).…”

Inuit women, decision-making and contaminants.

“…Lead is a widespread environmental contaminant with both natural and anthropogenic sources Dallaire et al, 2003;Substance Selection Task Force, 2003;Hermanson and Brozowski, 2005). As with other contaminants such as persistent organic pollutants (POPs), lead reaches the Arctic primarily through atmospheric and oceanic transport.…”