Multiple pathway asbestos exposure assessment for a Superfund community

Abstract

Libby, MT, USA, was the home to workers at a historical vermiculite mining facility and served as the processing and distribution center for this industrial product that was contaminated with amphibole asbestos. Several pathways of environmental asbestos exposure to the general population have been identified. The local clinic and health screening program collects data from participants on past occupational and environmental exposures to vermiculite and asbestos. Health studies among this population have demonstrated associations between amphibole exposure and health outcomes, but critical questions regarding the nature and level of exposure associated with specific outcomes remain unanswered. The objective of this study was to develop a comprehensive exposure assessment approach that integrates information on individuals' contact frequency with multiple exposure pathways. For 3031 participants, we describe cumulative exposure metrics for environmental exposures, occupational exposures, and residents' contact with carry-home asbestos from household workers. As expected, cumulative exposures for all three occupational categories were higher among men compared with women, and cumulative exposures for household contact and environmental pathways were higher among women. The comprehensive exposure assessment strategies will advance health studies and risk assessment approaches in this population with a complex history of both occupational and environmental asbestos exposure.

Case series: rheumatological manifestations attributed to exposure to Libby Asbestiform Amphiboles

“…The health outcomes of these exposures that were reported among exposed individuals include both malignant and non-malignant pulmonary diseases, with a severe and progressive pleural fibrosis being the predominant pulmonary outcome Black, et al 2014;Bunderson-Schelvan et al, 2011;Larson, et al 2012;Lockey, et al 2015;Peipins, et al 2003;Whitehouse 2004;Whitehouse, et al 2008). Due to the severity and extent of the asbestos-related disease (ARD) health impacts, Libby, along with the mine, was designated as an EPA Superfund site (Kuntz, et al 2009;Noonan, et al 2015;Winters, et al 2012;. A nested case-control study of the Libby population screened by the Agency for Toxic Substances and Disease Registry (ATSDR), showed that past LAA exposure was associated with reported systemic autoimmune diseases (SAID) (Noonan, et al 2006).…”

Pulmonary abnormalities as a result of exposure to Libby amphibole during childhood and adolescence—The Pre‐Adult Latency Study (PALS)

“…Where non‐mining related occupational exposures were identified in this population (16–30%), such histories were not associated with abnormalities nor did the inclusion of such histories change the risk estimates associated with environmental exposures to Libby amphibole. This environmental pathways exposure index (CEPE) combines frequency and duration of exposure with a weighted factor of the intensity of exposure in 11 different exposure pathways [Noonan et al, ]. The mean CEPE in this population was approximately 1 year weighted according to exposure pathway, with a range of 0–18 years.…”

“…Although this category corresponds to the highest likelihood of occupational LA exposure, other local occupations could have resulted in some contact with Libby amphibole‐contaminated vermiculate. Examples of local occupations with potential Libby amphibole exposure included construction, demolition or excavation, the railroad; work with commercial boilers or incinerators; agriculture or silviculture; cleaning residences or businesses; logging; plywood manufacturing, or other wood processing [Noonan et al, ]. Similarly, some occupations are known to be associated with exposure to commercial asbestos products [Rice and Heineman, ].…”

“…Four measures (in years) were used to quantify exposure, and tertiles were calculated. Approaches for quantifying environmental and occupational exposure histories in this population have been previously described [Noonan et al, ]. For brevity, the following summaries are provided: Cumulative Environmental Pathways Exposure (CEPE): contact with 11 historical environmental pathways, including frequency and duration.…”

Where Occupation and Environment Overlap: US Forest Service Worker Exposure to Libby Amphibole Fibers

“…Lastly, the USFS personnel are generally local residents who may have exposures to LA from other sources, depending on their lifestyle and indoor and outdoor activities. (16) …”