A survey of ethyl carbamate in fermented foods and beverages from Zhejiang, China

Abstract

A survey of ethyl carbamate (EC) in fermented foods and beverages was conducted in Zhejiang province, China. The samples comprised 184 alcoholic beverages (rice wine, white spirit, wine, beer, and rice cooking wine), 33 flavorings (soy sauces and vinegars) and 20 fermented sufus. Rice wine contained up to 515 μg/kg with an average of 160 μg/kg, and rice cooking wine up to 206 μg/kg with an average of 87 μg/kg. White spirits, wine and beer contained EC at an average level of 72 μg/kg, 16 μg/kg and 2 μg/kg, respectively. EC was also detected in soy sauces and vinegars at an average level of 47 μg/kg and 27 μg/kg. In fermented sufus, EC was found at an average level of 63 μg/kg in normal sufu and 182 μg/kg in red sufu.

Introduction

Ethyl carbamate (urethane) is genotoxic and carcinogenic in various animal species, including mice, rats, hamsters, and monkeys, which suggests a potential carcinogenic risk to human (Beland et al., 2005). Recently, the World Health Organization’s International Agency for Research on Cancer (IARC) re-classified ethyl carbamate (EC) as a group 2A carcinogen (probably carcinogenic to humans) (IARC, 2010). EC is absorbed rapidly and nearly completely from the gastro-intestinal tract and the skin (Cha et al., 2000, EFSA, 2007). As estimated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA), the Benchmark Dose Lower Limit (BMDL) of EC is 0.3 mg/kg bw per day, and the average intake of EC from food is approximately 15 ng/kg bw per day. With the inclusion of alcohol beverages, the estimated intake is 80 ng/kg bw per day. High consumption of stone-fruit brandies could lead to higher intakes of EC.

Considering that alcoholic beverages represent the higher part of EC intakes, several countries have set limits on their levels. Canada introduced guidelines and tolerance levels in alcoholic beverages in 1985, which set acceptable limits of 30 μg/L in table wines, 100 μg/L in fortified wines, 150 μg/L in distilled spirits, 200 μg/L in sakes, and 400 μg/L in fruit brandies and liqueurs (Conacher & Page, 1986). The USA set maximal levels for EC of 15 μg/L in table wines and 100 μg/L in fortified wines. Brazil set the limit of 150 μg/L in the sugarcane spirit cachaça (Lachenmeier et al., 2010). Unfortunately, there is no action on EC limits of alcoholic beverage or fermented foods in China.

In China, large numbers of fermented foods and beverages are produced and consumed every year. For example, in 2009, about 7.06 million tons of white spirits and 0.96 million tons of wines were made in China. In 2004, we carried out a survey of EC in local alcoholic beverages, which contained EC at a range of 88.2–240.8 μg/L in rice wine and 1.53–24.5 μg/L in wine (Wu & Chen, 2004).

In this study, the method of GC/MS with internal standard of d₅-ethyl carbamate was used for the quantification of EC, and the diatomite solid-phase extraction column was adopted for the analyte extraction. 237 samples (alcoholic beverages and fermented foods) were purchased from the local markets in Zhejiang province, China. Zhejiang near to the city of Shanghai is one of the developed districts in the southeast of China.