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Perspective
A current perspective on arsenic in wines: Analysis, speciation and changes in composition during production Courtney K. Tanabe, Jenny Nelson, and Susan E. Ebeler J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.9b00634 • Publication Date (Web): 21 Mar 2019 Downloaded from http://pubs.acs.org on March 22, 2019
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Journal of Agricultural and Food Chemistry
A current perspective on arsenic in wines: Analysis, speciation and changes in composition during production Courtney K. Tanabe1,2, Jenny Nelson1,2,3, Susan E. Ebeler*1,2 1Department 2Food
of Viticulture and Technology, University of California, Davis CA 95616 Safety and Measurement Facility, University of California, Davis CA 95616 3Agilent Technologies, Inc., Santa Clara, CA 95051
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Correspondence to:
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Susan E. Ebeler Department of Viticulture and Enology One Shields Avenue University of California, Davis Davis, CA 95616
[email protected] 1
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Abstract
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Arsenic, a naturally occurring metalloid found in certain foods, exists in various redox states and
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as inorganic and organic species, each with varying levels of toxicity. International regulatory
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bodies have imposed allowable maximums for total arsenic in wine ranging between 100-200
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g/L. Typical commercial wine levels are within these limits. However, a better understanding
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of viticultural and enological practices impacting total arsenic and arsenic species in grapes and
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wines is needed to ensure levels remain low. This Perspective discusses current information on
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factors impacting arsenic content of grapes and wines and the analytical approaches for
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monitoring inorganic and organic species.
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Journal of Agricultural and Food Chemistry
Introduction
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Arsenic is a monoisotopic metalloid intrinsically found in the environment, although it is
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not evenly distributed1. Variable concentrations in a given geographic region can be affected by
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both natural sources, like volcanic activity and weathering of bedrock, and anthropogenic
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sources, like mining and smelting1. Due to the ubiquitous nature of the element, its
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accumulation in the food chain poses potential health risks to consumers. The World Health
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Organization and recent studies in the US have indicated that diet can be a primary source of
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arsenic exposure for humans2, 3. Arsenic can be incorporated into both organic and inorganic
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compounds and each form can have different valence states. This is important because only the
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inorganic arsenic species are listed as a Group 1 carcinogen by the International Agency for
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Research on Cancer4, while the other arsenic forms are considered less toxic. To understand its
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toxicity in a food sample, different arsenic species should be monitored instead of simply
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analyzing total arsenic. Generally, the arsenic forms that are present and analyzed in food
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typically include inorganic forms (arsenite and arsenate), organic metabolites
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(monomethylarsonic acid and dimethylarsinic acid), and other organic species (arsenobetaine
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and arsenocholine) (Table 1).
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As a carcinogen and reproductive toxin5, the presence of arsenic in consumer goods is of
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general regulatory interest. In the United States there are no set regulations for maximum
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allowable limits of arsenic in grapes and wine. Other countries and regions follow regulations
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set by governing bodies that are between 100 and 200 g/L6, 7, however no regulatory limits
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exist for arsenic species in wine. As the public concern over levels of heavy metals in foods,
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including arsenic in wine, has increased, there have been multiple scientific investigations to
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develop methods needed for arsenic analysis in grapes and wine as well as to better
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understand variables influencing levels of arsenic in commercial wines. In this article we provide
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an overview and perspective on the current research and areas where further information is
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still needed to benefit the researcher, producer and consumer alike.
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For this perspective review, we will explore previous studies on arsenic measurement
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and speciation in wine. Our investigation will follow the whole wine production process starting
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with possible sources of contamination in the soil where the grapes are grown then proceed to
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processes of absorption and storage in the plant. Finally, possible transformations of arsenic
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species and concentration changes during winemaking processes will be examined. Special
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interest will be taken in all cases that show the effects of human influence on the arsenic
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concentration of wine. Various elemental techniques that have been used to analyze total
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arsenic concentrations and speciation in wine will also be discussed.
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Arsenic Species Present in the Environment and Transportation to Plants Arsenic is present in the Earth’s crust and exists within various types of rocks, with
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major primary arsenic containing minerals consisting of arsenopyrite, realgar, and orpiment1.
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The weathering of arsenic containing rocks as well as man-made activities, climate, the arsenic
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form, and redox conditions contribute to the concentrations in the soil. Soil levels range from
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