It is well known that wine is composed of a complex matrix of chemical compounds, which vary widely depending upon the soil, pesticide or fungicide use, winemaking process, storage process, and other steps along the way.  Metals may also be found in wine, the levels of which again vary, depending on the aforementioned factors.  One study presented earlier in the year by The Academic Wino showed that arsenic levels in wine were highly dependent upon the arsenic levels in the groundwater, showing that higher groundwater levels of arsenic corresponded to higher levels of arsenic in the finished wine.  Copper is another metal of interest in these types of studies, as over exposure to this element can have detrimental effects on the environment and human health.

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In the environment, long-term and intensive use and exposure to copper can have severe consequences, including the toxicity to aquatic and soil organisms, by accumulating in the soil at a rate faster than can be flushed out by the environment.  In regards to human health, there is a whole host of negative effects from excessive copper exposure and/or ingestion.  Copper is absorbed mostly via the intestinal tract.  20% to 60% of dietary copper is absorbed by the body, with any excess excreted. 

Copper poisoning or toxicity occurs when there is an excess of copper coming into the body, or homeostatic control mechanisms are defective, and most often is a result of elevated copper levels in beverages (most often, the water supply).  Adverse effects of copper toxicity in humans include nausea, abdominal pain, vomiting, and diarrhea.  Also, long-term exposure to copper may cause severe damage to the kidneys and liver, with liver damaged reported as occurring under copper levels greater than 30mg/day.  Some studies have examined long-term copper exposure and brain function, and have speculated that this exposure may trigger or speed up many neurological ailments; including Alzheimer’s disease, familial amyotrophic lateral sclerosis, and Creutzfeldt-Jakob disease, though so far, results have been inconclusive.

In the United States, the National Academy of Sciences limited the intake of copper to 10mg per day.  In the EU, the EU Scientific Committee on Food set this level to 5mg per day.  The Recommended Daily Allowance of copper for adult men and women has been set to 0.9mg per day.

As a result of the many adverse environmental and human health effects of copper exposure, it is important to monitor its levels in food and beverage items, including wine.  In high wine-consuming countries, such as Croatia, where metal concentrations in the soil are relatively higher than other grape-growing regions, this type of copper monitoring is very important.  The International Organization of Vine and Wine and the Croatian government has put limits on the maximum allowed levels of copper in wine, which equates to 1000μg/L.

The goal of today’s study was to determine the contribution of Croatian wine to the dietary intake of copper and to make implications for possible human health risks for moderate wine consumers.

In order to evaluate this, one group of scientists from Croatia used data based on national estimates of average wine consumption rates (derived from the general population).  They analyzed 10 commercial and 15 homemade wines from 13 winemakers from 6 Croatian growing regions for copper levels using graphite furnace atomic absorption.  Using the levels of copper found in the wine, coupled with the data for average wine consumption in Croatia, they then compared these copper intake levels with the maximum permissible levels of copper and the highest tolerable levels of copper. 

Results

•       Median copper levels in commercial wines were 180μg/L (range: 76μg/L to 292μg/L).
•       Median copper levels in homemade wines were 258μg/L (range: 115μg/L to 7600μg/L).

o   In 10 out of the homemade wines, copper levels were below the upper threshold permissible limit of 1000ug/L.

o   Three of the homemade wines contained copper levels that were higher than the upper threshold permissible limit, which may have been due to very intensive use of copper-laden fungicides, too short of time between application and harvest, or ignoring the limits set forth by the government.

•       There were no statistically significant differences in copper levels between the commercial and the homemade wines and between red and white wines.

Summary

The results of this study showed that for the most part, copper levels in Croatian wines are low, and are well below the established upper threshold permissible limits.  Even though the majority of the wines were low in copper, a small number of the homemade wines showed copper levels much higher than the upper threshold permissible limits.  This result indicates the need to be sure that winemakers are aware of the possible sources of the metal getting into their wines, and to use appropriate corrective techniques to avoid elevated concentrations in the finished wines.

Using the average wine consumption data collected from the general population (0.2L per day for moderate wine consumption) and the copper levels found in the wines studied, the authors were able to calculate that individuals consuming the commercial wines on average ingested between 0.04mg/day and 0.06mg/day of copper.  Examining the homemade wine with the highest copper levels, the authors calculated that individuals consuming this wine on average ingested 1.52mg/day of copper.  According to these values, even the wine with the highest level of copper would not pose any problems for moderate wine consumers (drinking an average of 0.2L per day).

However, individuals who are heavy wine consumers (those who consume over 0.5L/day) would end up ingesting copper at levels higher than the tolerable intake levels, if they were consuming some of the wines in this study (particular the wines with the higher copper levels), which could potentially result in harmful health consequences.

Overall, however, the study showed that for the most part, Croatian wines (or at least most of the wines studied in their experiment) are completely safe to consume for low to moderate wine drinkers.  However, since there are individuals who drink more wine than the average consumer, it’s important for winemakers to monitor the copper levels in their wines, and to take the necessary steps possible to minimize these levels in their finished wines.

I’d love to hear what you all think!  Please feel free to leave your comments below!

Source: Tariba, B., Kljaković-Gašpić, Z., and Pizent, A. 2011. Estimation of copper intake in moderate wine consumers in Croatia. Arhiv Za Higijenu Rada Toksikologiju 62: 229-234.

DOI: 10.2478/10004-1254-62-2011-2109
I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!