Int. J. Environ. Res. Public Health 2011, 8(12), 4729-4745; doi:10.3390/ijerph8124729
Article

Determining the Maximum Cumulative Ratios for Mixtures Observed in Ground Water Wells Used as Drinking Water Supplies in the United States

Toxicology and Environmental Research and Consulting, The Dow Chemical Company, 1803 Building, Midland, MI 48674, USA
* Author to whom correspondence should be addressed.
Received: 9 October 2011; in revised form: 13 December 2011 / Accepted: 13 December 2011 / Published: 19 December 2011
(This article belongs to the Special Issue Cumulative Health Risk Assessment)
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Abstract: The maximum cumulative ratio (MCR) developed in previous work is a tool to evaluate the need to perform cumulative risk assessments. MCR is the ratio of the cumulative exposures to multiple chemicals to the maximum exposure from one of the chemicals when exposures are described using a common metric. This tool is used to evaluate mixtures of chemicals measured in samples of untreated ground water as source for drinking water systems in the United States. The mixtures of chemicals in this dataset differ from those examined in our previous work both in terms of the predicted toxicity and compounds measured. Despite these differences, MCR values in this study follow patterns similar to those seen earlier. MCR values for the mixtures have a mean (range) of 2.2 (1.03–5.4) that is much smaller than the mean (range) of 16 (5–34) in the mixtures in previous study. The MCR values of the mixtures decline as Hazard Index (HI) values increase. MCR values for mixtures with larger HI values are not affected by possible contributions from chemicals that may occur at levels below the detection limits. This work provides a second example of use of the MCR tool in the evaluation of mixtures that occur in the environment.
Keywords: cumulative; risk assessment; exposure; mixtures; groundwater; Hazard Index; MCR

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MDPI and ACS Style

Han, X.; Price, P.S. Determining the Maximum Cumulative Ratios for Mixtures Observed in Ground Water Wells Used as Drinking Water Supplies in the United States. Int. J. Environ. Res. Public Health 2011, 8, 4729-4745.

AMA Style

Han X, Price PS. Determining the Maximum Cumulative Ratios for Mixtures Observed in Ground Water Wells Used as Drinking Water Supplies in the United States. International Journal of Environmental Research and Public Health. 2011; 8(12):4729-4745.

Chicago/Turabian Style

Han, Xianglu; Price, Paul S. 2011. "Determining the Maximum Cumulative Ratios for Mixtures Observed in Ground Water Wells Used as Drinking Water Supplies in the United States." Int. J. Environ. Res. Public Health 8, no. 12: 4729-4745.

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