A Comprehensive Review of Spirit Drink Safety Standards and Regulations from an International Perspective

The term “alcoholic beverage” refers to a drink that contains a certain amount of ethanol; however, the legal definitions for alcoholic beverages vary because the minimum alcohol concentration requirements differ across countries. For example, the People's Republic of China has defined an alcoholic beverage as any beverage that contains 0.5% or more of pure alcohol (34); Canada regulates a beverage as an alcoholic beverage if it contains ≥1.1% alcohol by volume (39); and the legal levels of alcohol are 0.5% alcohol by volume in the United States (86), 1.2% in the European region (17), and ≥7% in Belarus, which is the highest legal level worldwide (95). According to distinct processing methods and product properties, alcoholic beverages can be classified into fermented alcoholic drinks (such as wine, beer, and rice wine), distilled spirit beverages, and aromatized alcoholic beverages (8, 34).

Alcoholic beverages are popular worldwide not only because they possess special flavors, but also because they have long been a part of human life and culture. Recent data from the World Health Organization indicate that globally, people aged 15 years and older drink, on average, 6.2 liters of pure alcohol per year, which translates to 13.5 g of pure alcohol per day (95). Moreover, 50.1% of the total recorded alcohol consumption worldwide is in the form of spirits, whereas the second largest proportion includes beer, which accounts for 34.8% of the consumption. In addition, 8.0% of the total recorded alcohol is consumed in the form of wine, and “other” alcoholic beverages (e.g., fortified wines, rice wine, or other fermented alcoholic beverages) represent 7.1% of the total alcohol consumption (Fig. 1). Thus, pure alcohol consumption in the form of spirits equals the total amount consumed in the form of all other alcoholic beverages, possibly because of the popularity and the high ethanol content of spirits, in which ethanol is concentrated through distillation.

The most highly consumed spirits in the world include brandy, gin, rum, vodka, whisky (or whiskey) and Chinese liquor (98). Ethanol and water are the main components of spirits, which vary according to their distinctive compositions of raw materials and fermentation and distillation processes (7, 97). Most components in spirits, such as volatile components, contribute to the flavor of the beverage; however, certain compounds are potentially hazardous at high concentrations and will negatively affect alcohol quality, such as methanol, ethyl carbamate, and aldehydes. “Alcohol quality” might refer to taste, flavor, price, brand image, or the absence of certain toxic contaminants (55). Here, we focus primarily on substances present in spirit drinks that are relevant to public health. The processing flow of spirits is widely recognized to include mainly raw material preparation, fermentation, distillation, and aging. Some hazardous substances, such as patulin, come from raw materials, and others come from contamination with instruments or the environment, such as lead (Pb); however, most of the hazardous compounds come from the processing flow, and their amounts even increase during aging, as in the case of ethyl carbamate.

Safety and quality requirements related to distinct types of spirit drinks have been established by certain countries and international organizations, such as the Codex Alimentarius Commission (CAC), the European Union (EU), Canada, the United States, China, Australia, and New Zealand. These standards applicable to spirit drinks are aimed to improve quality and protect consumers, but certain differences in their details exist because of variations in, for example, raw materials, product properties, consumption quantity in the diet, and processing techniques.

To obtain complete information regarding the maximum levels (MLs) of contaminants in spirit drinks, relative requirements and studies were widely searched on the Web sites of authorities in different countries and in the following databases: Web of Science, Taylor & Francis, and Food Science and Technology Abstracts. The data show that the indicators related to spirit safety and quality in current legislation and standards include methanol, higher alcohols, ethyl carbamate, hydrocyanic acid (HCN), Pb, patulin, phthalates, and aldehydes.

In this review article, we introduce relative standards and the principles related to establishing standards, compare key indicators, and analyze potential risks to predict how standards could be amended. Furthermore, this review article provides knowledge regarding the control measures used for potential hazards, which will benefit producers, traders, and governments.

To provide an enhanced understanding of the indicators used for food safety, the principles and related authorities for establishing standards are introduced first. Table 1 summarizes the key standards related to spirit safety and quality in various countries and organizations, including the CAC, EU, Canada, the United States, the People's Republic of China, Australia, and New Zealand. Among various standards, Codex standards are recognized as international food standards established by the CAC that contribute to protecting the health of consumers and ensuring fair practices in the food trade. The standards and principles of the CAC have influenced food safety policy in other countries. Both general standards and relevant detailed product standards have been established in the EU, China, the United States, Australia, and New Zealand to control spirit quality; by contrast, the CAC and Canada mainly adopt general standards and related guidelines to control general contaminants in spirits.

The CAC has regulated the food additives applied to distilled spirituous beverages containing more than 15% alcohol (8), but an exact spirit standard is not currently available in the list of Codex standards (13). Codex STAN 193-1995 “General Standard for Contaminants and Toxins in Food and Feed” is a general food safety standard developed by the Codex Committee on Contaminants in Foods (9). The CAC defines “contaminant” as any substance not intentionally added to food that is present in food as a result of production, manufacture, processing, preparation, treatment, packing, packaging, transport, or holding or as a result of environmental contamination. The MLs of mycotoxins, heavy metals, radionuclides, and other contaminants are established in this standard. Among the parameters, very few MLs are for alcoholic beverages, such as Pb for wine and patulin for cider (9). Risk assessments have been conducted to evaluate whether there is a need to establish MLs for certain contaminants in distinct foods in accordance with the principles of CAC/GL 62-2007 (11). The MLs for certain chemicals have been established according to toxicological information, dietary intake data, and technological measures (such as Good Agricultural Practices and Good Manufacturing Practices).

In the EU, the definition, description, labeling, and geographical indications of spirit drinks are regulated in Regulation (EC) No 110/2008 (20). Spirit drink refers to an alcoholic beverage that features a minimum alcoholic strength of 15% by volume that could be produced by distillation of fermented products or a mixture of a spirit drink with one or more other drinks together with or without flavorings, sugars, or other sweetening products, possesses specific organoleptic qualities, and is intended for human consumption. The safety and quality requirements for spirits have also been detailed in the technical definitions and requirements of Annex 1, according to the detailed category (20). The EU has set MLs for certain contaminants in foods, and some of the indicators, such as patulin are applicable to spirits (19). Moreover, the European Food Safety Authority (EFSA) was established and funded under the EU budget. As an independent agency, the EFSA must provide scientific advice and technical support for legislation and policies in all fields that directly or indirectly affect food safety. The EFSA has provided risk assessment information on various contaminants, such as mycotoxins, phthalates, and ethyl carbamate (18, 22).

In the United States, the U.S. Department of the Treasury, Alcohol and Tobacco Tax and Trade Bureau administers alcohol production, importation, wholesale distribution, labeling, and advertising. The U.S. Food and Drug Administration (FDA) is responsible for wine that contains <7% alcohol; the FDA is also in charge of handling the presence of poisonous substances in alcoholic beverages, such as methanol. There is detailed information about the definition, labeling, and basic permits of alcoholic beverages in the Code of Federal Regulations Title 27 (86). Although no specific standards for contaminants in food are available, the FDA has developed a series of guidelines and regulations for different types of products, which can be obtained from the FDA guidance for industry regarding action levels for poisonous or deleterious substances in human food and animal feed (87). Furthermore, the Compliance Policy Guide was developed to explain the FDA policy that provides the standards and procedures required to determine industry compliance (88). If the content of a poisonous substance in a product is above the action level and tolerance limit, the FDA takes legal action to remove the product from the market. Where no established action level or tolerance limit exists, the FDA might take legal action to remove the products, based on the minimal detectable level of the contaminant.

Canada has established specific descriptions for several types of spirit drinks, such as vodka, gin, whisky, and rum, in the basic law Food and Drug Regulation (39). At the federal level in Canada, the responsibility for food safety is shared by two organizations: Health Canada and the Canadian Food Inspection Agency (51). Health Canada is responsible for establishing standards for the safety and nutritional quality of all foods sold in Canada and exercises this mandate under the authority of the Food and Drugs Act, and it pursues its regulatory mandate under the Food and Drug Regulation (44). Health Canada has established a list of various chemicals in specified retail foods, and the standards are enforced by the Canadian Food Inspection Agency to ensure that Canadians are not exposed to high levels of chemical contaminants in their diet (45). Among various chemicals on the list, the amount of ethyl carbamate is strictly limited in different types of alcoholic beverages, and this was the first standard regulation for the ML of ethyl carbamate (33, 45).

Australia and New Zealand work together through Food Standards Australia New Zealand (FSANZ) and other cooperative agreements (37). FSANZ is responsible for developing the Food Standards Code that regulates the use of ingredients, processing aids, colorings, additives, vitamins, and minerals. The code also covers product standards for dairy, meat, and beverages. Food Safety Standards are available through FSANZ (31). Standard 1.4.1 “Contaminants and Natural Toxicants” and Standard 1.3.1 “Food Additives” are mandatory, although not all indicators are applicable to spirits (30, 32). One available product standard is Standard 2.7.5 “Spirits,” which mainly specifies definitions, addition of other foods, and geographical indications (29).

Chinese liquor, Baijiu in Chinese, is a traditional alcoholic beverage produced through the distillation of fermented cereals, with Daqu being used as a fermentation starter (99). Because of its unique flavor, Chinese liquor is extremely popular in the People's Republic of China; 10 billion liters of the drink are consumed annually (7). Chinese liquor production must follow the Food Safety Law, which is the basic law mandatory for supervisors, manufacturers, traders, and inspection institutes in China (79). According to the Food Safety Law, the National Health and Family Planning Commission (originally the Ministry of Health) is responsible for developing and publicizing the national food safety standards after approval by the national food safety standard evaluation committee, which includes experts from relevant departments (50). The National Food Safety Assessment Centre performs scientific risk assessment to develop and amend food safety standards (62). Both general standards and product standards are established to ensure food safety. The most critical standard related to spirit quality and safety is GB 2757-2012 “National Food Safety Standard for Distilled Spirits and Formulated Spirits” (72). For contaminants such as heavy metals, GB 2762-2012 “National Food Safety Standard for Maximum Levels of Contaminants in Foods” must be followed (73), and mycotoxin limits must meet the requirements of GB 2761-2011 “National Food Safety Standard for Maximum Levels of Mycotoxins in Food” (70). These standards are mandatory for both domestic and imported products sold in the markets of China (82). In addition to the aforementioned general standards, various recommended product standards have been made by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, which was in charge of product quality and import-export food safety before the State Council reform in 2013 (50). These standards include requirements for raw materials, processing flow, brewing environment, alcohol content, organoleptic characteristics, packing, labeling, and geographical indication protection (82). For any liquor production in China, a production license must be acquired first, and the production must follow GB 8951 “Hygienic Specifications of Liquor Factory” (68). The existing standards will be integrated for a systematic standard framework (63). Only with the enhancing management in the production process could the toxic and hazardous compounds be reduced (27).

In summary, some international organizations and countries have established requirements to ensure the safety and quality of alcoholic beverages. Most requirements are in the form of standards, whereas a few are in the form of regulations or guidance. Regardless of the form, a crucial risk management measure is the establishment of MLs for chemical contaminants in foods. When establishing MLs for contaminants in foods, the amount of food consumed and the toxicity and concentration of the chemicals in food must also be considered. The nonconformity of a product does not inevitably mean that the product is poisonous according to the risk assessment principles; however, to ensure efficient protection of public health, products that do not conform to established standards must not be sold in markets or used as ingredients in other foods.

According to the aforementioned principles of risk assessment and what can be technically achieved, the MLs for a particular contaminant might differ depending on the type of spirits and their consumption in different countries. In Table 2, we compare the most critical indicators related to the safety and quality requirements of spirits in the different standards of the CAC, the EU, the People's Republic of China, the United States, Canada, and Australia and New Zealand.

Methanol. Various indicators of safety and quality are used in different countries, but most countries have set the ML for methanol. Methanol smells like ethanol and is soluble in ethanol in any proportion. However, two metabolites of methanol, formic acid and formaldehyde, can accumulate in tissues and harm the optical nerve; ingestion of 10 ml of pure methanol can cause permanent blindness, and ingestion of 30 ml is potentially fatal (89). Because of methanol's chemical and toxic properties, methanol concentration is one of the most critical parameters in spirit standards.

Methanol is primarily generated from pectin through enzymatic breakdown, and then it migrates into spirit drinks during distillation because it is highly volatile (36). Thus, methanol is a major toxic volatile compound present in alcoholic beverages, particularly when products with a high pectin content, such as potatoes and fruits, which contain more pectin than cereals, are used as raw materials.

However, the major methanol poisoning cases in the last decade were caused by economically motivated adulteration of alcoholic beverages (25). In 2001, illegal spirits containing 50 to 100% methanol were sold and consumed in Estonia, and 154 patients were verified to have methanol poisoning; 68 patients died (59). Such illegal spirits are banned and can potentially be controlled through strict supervision by governments. By contrast, methanol formed from pectin is typically associated with raw materials and processing techniques and cannot be completely avoided, even when controlled strictly.

The MLs of methanol in the EU range from 0.05 g/liter for London gin to 15.0 g/liter for fruit marc spirits. The methanol limit established for London gin is the lowest, possibly because of the processing flow used: the gin is obtained exclusively from ethyl alcohol of agricultural origin through redistillation, which might reduce the methanol content in the end products. FSANZ has set the following MLs for methanol: 0.4 g/liter for whisky, rum, gin, and vodka and 8.0 g/liter for other spirits (32). In the People's Republic of China, the methanol concentration cannot exceed 0.6 g/liter in spirits that are distilled from fermented cereals; in other spirits, the concentration must be <2.0 g/liter. The ML for methanol in the United States is 0.35% for imported brandy (84). The CAC and Canada have not developed detailed rules regarding methanol limits.

Enzymatic treatment of pectin is occasionally used to increase ethanol yield, but this concurrently increases the methanol content (35, 80). To reduce methanol formation during processing, the use of raw materials that contain extremely high levels of pectin, such as potatoes and fruits, must be reduced, and storage conditions, such as pH, temperature, and humidity, must also be tightly controlled to avoid spoilage and thereby prevent pectin degradation (14). Finally, distillation is a key step in which the concentration of methanol can be decreased by removing the first distillate (90). Thus, a careful distillation has been recommended for reducing methanol content, although this also lowers the alcoholic yield.

Higher alcohols. Methanol is the simplest, lowest molecular weight alcohol. Alcohols that contain >2 carbon atoms are commonly called higher or fusel alcohols, and these include, for example, propanol, butanol, isobutanol, and isoamyl alcohol. Higher alcohols are formed through yeast metabolism from amino acids; therefore, these alcohols exist naturally in alcoholic beverages and contribute to flavor and taste (46). Zhao et al. (97) analyzed the characterization of the volatile fraction of the six most well-known distilled spirits in the world. Among the 158 identified compounds, 25 were common to all the distilled spirits samples and were mainly esters, higher alcohols, and benzene derivatives (97). Some other studies also showed that higher alcohols were one category of the major volatile compounds in spirits (16). However, some previous studies have attributed the poor quality or potentially higher toxicity of alcohol to the content of higher alcohols (59, 66).

In the EU, the very low ML for higher alcohols 0.005 g/liter expressed in methyl2 propanol1 only refers to ethyl alcohol of agricultural origin. For spirits, there are no limits in EU legislation. The EU even demands minimum volatile substance content (the quantity of volatile substances, mainly higher alcohols, other than ethanol and methanol). For example, the minimum content for rum, fruit spirit, grape marc spirits, and wine spirits is 2.25, 2.00, 1.40, and 1.25 g/liter, respectively (20). In China, higher alcohols were not allowed to exceed 2 g/liter, according to the past hygiene standard for distilled spirits GB 2757-1981 (67). In the new standard GB 2757-2012, the safety indicator of higher alcohols has been omitted according to the test results of recent decades. No requirements for higher alcohol limits have been set in the other countries mentioned in this article (72).

Lachenmeier et al. (53) analyzed the concentrations of higher alcohols in 290 spirit samples that included all typical groups in the European market and found that the mean content of higher alcohols was approximately 4 g/liter; furthermore, the acceptable daily intake value for higher alcohols was calculated in the study to estimate tolerable concentrations of higher alcohols. The conclusion reached was that a reasonable preliminary “guideline” level could be 10 g/liter for the combined amount of all higher alcohols (53). This indicates that there is no safety concern regarding higher alcohols in alcoholic beverages, as the concentration is usually lower than the reasonable level.

In summary, higher alcohols are considered to be either important flavoring compounds or toxic substances, depending on their concentration. The traditional method of reducing higher alcohols content involves rigid control of the brewing process: selecting raw materials with low protein content, using yeast with low activity protease, and controlling the ambient temperature during brewing. A novel method of removal of excessive fusel alcohols from rice spirits was investigated by using nanofiltration, which achieved a higher score in a sensory evaluation (47). At present, most studies indicate that higher alcohol is not a safety risk for spirits under normal processing.

Ethyl carbamate. Ethyl carbamate has been detected in several types of fermented foods and beverages (43), such as bread (41), soy sauce, soybean paste (52), and alcoholic beverages (56), particularly stone fruit spirits (57). Ethyl carbamate is typically formed from various precursors, and one of the most important precursors is urea, which might be formed during the degradation of arginine by yeast; another source is cyanate from the oxidation of cyanide (81, 91). The precursors react with ethanol to form ethyl carbamate, and this occurs even during storage after distillation, which explains why the concentration of the chemical in spirits is high (91).

The presence of ethyl carbamate in spirits has been a public health concern since 1985, when high levels were detected by Canadian authorities in alcoholic beverages, especially in spirit drinks imported from Germany (33). Subsequently, Canada established the following ethyl carbamate guidelines: 30 μg/liter for table wines, 100 μg/liter for fortified wines, 150 μg/liter for distilled spirits, and 400 μg/liter for fruit spirits (45). The United States has established voluntary targets of 15 μg/liter in wine and 60 μg/liter in fortified wine that are not applicable to spirits (22). Currently, no specific ML for ethyl carbamate in spirits is provided by the CAC or EU, but the EU has performed a risk assessment for establishing a limit of ethyl carbamate in spirits (22); furthermore, the EU recommended a target level of 1 mg/liter. If the distillate shows an ethyl carbamate concentration exceeding the target, the distillate should be redistilled (23). The CAC has proposed a code of practice for the prevention of ethyl carbamate contamination in stone fruit spirits (12). In the People's Republic of China, the National Health and Family Planning Commission published the national food safety standard for ethyl carbamate determination: 145 alcoholic beverage samples from markets in eight regions of the country were tested, and the average concentrations of ethyl carbamate in wines and grain spirits were reported to be 14.7 and 33.8 μg/kg, respectively (64). Another study showed the average concentration of ethyl carbamate in different types of Chinese liquor is 100 μg/liter (26). MLs for different kinds of alcoholic beverages will be established according to risk assessment.

In 2007, the International Agency for Research on Cancer initiated an evaluation of the carcinogenic risk posed by ethyl carbamate to humans, and the overall conclusion reached was that ethyl carbamate is probably carcinogenic to humans (group 2A) (49). Moreover, the EFSA analyzed 33,000 test results of alcoholic beverages and developed a scientific opinion on the findings of the panel on ethyl carbamate in food and beverages. Risk characterization was performed with a margin of exposure (MOE) approach. Typically, a value under 10,000 indicates a public health risk; the lower the MOE value, the higher will be the risk for humans. An MOE of almost 18,000 was calculated for exposure to ethyl carbamate in food in the absence of alcoholic beverages, which indicates a low risk for human health. However, the calculated MOE was approximately 5,000 for food, if consumed together with a variety of alcoholic beverages. Thus, the conclusion was that the presence of ethyl carbamate in alcoholic beverages is a health concern (22).

Currently, measures to reduce ethyl carbamate levels are concentrated on reducing the levels of the precursors, urea and cyanide (96). Furthermore, these preventive measures also include Good Manufacturing Practices, such as the use of high-quality, unspoiled raw materials and high standards of hygiene during fermentation. However, after UV irradiation, the concentration of ethyl carbamate typically rises above the accepted upper limit; thus, ethyl carbamate cannot be completely avoided because it occurs naturally in fermented foods and beverages. In summary, a scientific ML for ethyl carbamate must be established based on risk assessment, and the levels of this chemical in spirits must be periodically monitored by producers and supervisors.

HCN. HCN is formed as a result of the enzymatic hydrolysis of cyanogenic glycosides, which are produced by various plant species, such as stone fruit species and cassava (42). Cyanogenic glycosides in plants are mostly nontoxic until HCN is released (1).

The EFSA estimated the dietary exposure to HCN and found that exposure was mainly from food products and not from alcoholic beverages. Thus, the HCN present in most alcoholic beverages does not pose a risk of acute toxicity. Moreover, the relationship between ethyl carbamate and HCN was evaluated because HCN is a key precursor of ethyl carbamate. Although no strong correlation was identified, all samples that contained high levels of HCN also contained elevated levels of ethyl carbamate. Thus, people who consume large amounts of fruit brandy containing high levels of HCN could be exposed to high levels of ethyl carbamate (22).

Regulation (EC) No 110/2008 established the ML for HCN only in the case of stone fruit spirits: 70 mg/liter (20). In China, cyanide levels in spirits cannot exceed 8.0 mg/liter as expressed in HCN (72). FSANZ has set the strictest limit for HCN in alcoholic beverages: 1 mg/liter (32). In the United States, elder tree leaves and peach leaves can be used as flavor in alcoholic beverages, “not to exceed 25 ppm prussic acid (HCN) in the flavor,” but there are no definite MLs for HCN in spirits (section 172.510 of CFR Title 21 (85)). The CAC did not establish a definite limit for HCN but noted a potential increase in ethyl carbamate formation with levels at or above 1 mg/liter of HCN in the final distillate. If the concentration of HCN in the distillate exceeds 1 mg/liter, redistillation is recommended (12). Thus far, Canada has not developed MLs for HCN in spirits.

The use of high pressure or thermal treatment to the fruit pulp before fermentation had been reported to cause a statistically significant reduction in HCN levels. Increasing the treatment temperature inactivates the native enzymes that catalyze the hydrolysis of cyanogenic glycosides present in fruits (1).

Pb. Pb is a heavy metal that poisons the nervous system and causes brain disorders. Exposure to Pb through consumption comes mainly from agriculture products, meats, and aquatic products, which are affected by severe industrial pollution (2, 94). The presence of heavy metals in raw materials could be effectively prevented through distillation; the Pb present in spirit drinks comes mainly from equipment and containers during manufacture, distribution, or storage. However, the major source of Pb exposure is not related to the consumption of alcoholic beverages, which contributes only about 7% of the total Pb exposure from foods and beverages (54).

Both the CAC and EU recommend the ML of 0.2 mg/kg for Pb in wine but have set no specific limit for spirits (8, 19). However, the EU has specifically ruled that spirit drinks must not be stored in containers fitted with closing devices covered by Pb-based capsules or foil (20). FSANZ has not set the ML for Pb in alcoholic beverages (32). China has set a strict ML for Pb of 0.5 mg/kg in spirits and 0.2 mg/kg in other alcoholic beverages (73). In summary, Pb in spirit drinks is derived mainly from equipment or containers. Thus, the recommendation is that the use of Pb foil capsules must be avoided to reduce and prevent Pb contamination.

Patulin. Patulin is a mycotoxin produced during secondary metabolism in the genera Aspergillus, Penicillium, and Byssochlamys. Patulin is immunotoxic at high doses but is not carcinogenic to humans (38). Patulin can be detected as a natural contaminant in numerous fruits, including apples, pears, grapes, and hawthorn (100), and it is frequently present in commercial fruit juices, particularly apple juice produced by using unqualified fruits (38, 40).

The natural occurrence of patulin in foodstuffs has raised international awareness regarding this contaminant. Currently, the CAC recommends that the ML for patulin must be <50 μg/kg in apple juice and in apple juice ingredients included in other beverages (9). The EU has established the ML for patulin as 10 μg/kg in apple juice and 50 μg/kg in spirit drinks, cider, and other fermented drinks made from apples (19). China has set a similar ML for patulin: 50 μg/kg in alcoholic beverages derived from apple and hawthorn (73).

The standards established currently do not include MLs for other mycotoxins because distillation procedures reduce the occurrence and the levels of nonvolatile compounds in distillate spirits. Nagatomi et al. (75) studied the fate of 13 representative mycotoxins during the distillation process of barley shochu and indicated that distillation can effectively minimize the risk of mycotoxins in spirits. The CAC has recommended Good Agricultural Practices and Good Manufacturing Practices for reducing patulin contamination in apple-based products (10). Moreover, a previous study has shown that patulin levels in apple juice could be reduced through pasteurization, enzymatic treatment, microfiltration, and evaporation processes (92).

Plasticizers. Plasticizers are commonly added to plastic products to increase their flexibility, durability, and pliability. In various plastic products, the most frequently used plasticizers are phthalates such as di-2-ethylhexyl phthalate (DEHP), di-isononyl phthalate (DINP), di-isodecyl phthalate, di-butyl phthalate (DBP), butyl benzyl phthalate, and di-isobutyl phthalate (65). Plasticizers tend to readily migrate from plastic materials into foods featuring a high fatty or alcohol content during production, transportation, and storage. Exposure to phthalates is considered to be potentially harmful to human health (93). Consequently, a key problem that requires attention is that of monitoring the migration of plasticizers into alcoholic beverages.

Currently, no MLs are set for phthalates in wine or spirits in the CAC or EU. However, the concentrations of these undesirable substances are limited indirectly by regulations on materials that contact foods. In these regulations, specific migration limits have been established. For example, the specific migration limits for DBP, butylbenzyl phthalate, DEHP, and DINP are 0.3, 30.0, 1.5, and 9.0 mg/kg, respectively (24). Chatonnet et al. (4) measured the concentrations of various phthalates in grape spirits, and they recorded the highest concentrations for DBP and DEHP (average concentrations, 0.314 and 0.513 mg/kg, respectively); these measurements of phthalate content at levels above the specific migration limits indicated that the products might have been contaminated by noncompliant packing materials (4).

The People's Republic of China has also established a national standard for materials that contact food, GB 9685-2008, and the specific migration limit used here is similar to that of the EU (69). However, two plasticizer cases in 2011 raised considerable public concern in China. In the first case of the Taiwan plasticizer event, the plasticizer was illegally added into food rather than an emulsifier to lower cost, and the plasticizer contaminated products, such as beverages, fruit jams, and food additives (60). In the second case of plasticizers in Chinese liquor, certain Chinese liquors were contaminated with plastic materials, but these were not illegally added as in the first case. To ensure food safety, China's health authority has established a guideline based on risk assessment, and has set MLs of 5.0, 9.0, and 1.0 mg/kg for DEHP, DINP, and DBP, respectively. This is not a food safety standard and is only used for supervision to judge an illegal addition (5, 71, 77, 78).

In the United States, the basic regulation Code of Federal Regulations Title 21 provides detailed requirements regarding, for example, the specifications and usage conditions of phthalates. In Canada, established regulations prohibit the sale of food containers that might transfer harmful substances to their contents, and the same regulation applies in the case of the Australia and New Zealand requirements (28).

Unqualified products have been investigated previously, and action has been taken to reduce phthalate content in materials. The findings, thus far, suggest that the use of qualified materials and processing can facilitate a rapid reduction of phthalate contamination (4).

Aldehydes. The EU has set the following limit for aldehydes: 0.005 g/liter for acetaldehyde and furfural that cannot be detected in ethanol of agricultural origin, which is used for the production of spirits, such as gin or most other spirits. However, no specific limits have been established for any other type of aldehyde in distilled spirits (20). Other countries have not set limits related to aldehydes.

In alcoholic beverages, acetaldehyde is formed through two pathways: (i) it is produced by yeast and acetic acid bacteria as a metabolic by-product during fermentation; and (ii) it is produced through auto-oxidation of ethanol and phenolic compounds. At low levels, acetaldehyde can provide a pleasant fruity aroma, but at high concentrations, it possesses a pungent irritating odor and might pose health hazards (58). Because acetaldehyde is enriched in the first fraction during distillation, aldehyde levels can generally be reduced by discarding the first fraction or through rectification, as in the case of vodka. To avoid the formation of acetaldehyde after distillation, the absence of air is favorable at low temperatures (6, 58).

Besides the contaminants, potential risks from food additives may cause safety problems. Various food additives, especially flavorings, were often used in flavored or aromatized alcoholic beverages to improve the odor or taste. For instance, flavorings include kinds of chemical and natural flavoring substances. Some undesirable substances might be naturally present in the food ingredients with flavoring properties. Appropriate MLs should be established for food additives, taking into account both the need to protect human health and their unavoidable presence in foods.

The CAC established Codex STAN 192-1995 “General Standard for Food Additives” is usually adopted or partly applied by many countries (8). In the EU, the use of flavoring substances should follow Regulation (EC) No 1334/2008 (21). The United States listed the permitted food additives in the CFR Title 21 Parts 172 to 178 (85). Canada also made a food additives list in Division 16 of the Food and Drug Regulations (39). In China, the application of food additives must follow GB 2760-2014 “National Food Safety Standard for Food Additive Using” (76). FSANZ established Standard 1.3.1 “Food Additives” (34) and Standard 1.4.1 “Contaminants and Natural Toxicants” (32), which set MLs for natural toxicants from the addition of flavoring substances.

The detailed scope and MLs of the same substance differ across countries or regions. For example, thujone, an active ingredient in absinth from the ingredient Artemisia or wormwood, is forbidden in Codex STAN 192-1995 (8), and the requirement of the United States is a “finished alcoholic beverage thujone free” (section 172.510 of CFR Title 21 (85)). The EU set the MLs as 35 mg/kg in alcoholic beverages produced from Artemisia species and 10 mg/kg for other alcoholic beverages (21). Australia and New Zealand also set MLs of 10 mg/kg for alcoholic beverages (32). In China, wormwood and its extract are permitted for use as a natural flavoring, and there is no limit for thujone at present (76). In summary, the principles and general rules for food additive use are generally similar in different countries. Food additives can only be used as permitted and must follow the application scopes and MLs.

The preceding section has summarized the safety indicators related to spirit drinks that are included in the standards of several representative countries and organizations. The setting of MLs for contaminants in foods is one of the most important risk management measures in many countries, although the detailed requirements regarding the types of parameters and MLs generally differ (Table 2). Economic globalization has caused food supplier networks to expand rapidly among different counties and regions. However, trade disputes related to food and beverage occur occasionally, and these can place large quantities of food at risk of destruction because distinct standards and legislations are used in different countries (51). For example, great differences in the methanol limit requirement exist among the United States, the EU, Australia and New Zealand, and China (Table 2). Thus, these governmental requirements must be harmonized to avoid trade disputes, increase trading efficiency, and enhance the quality and safety of distilled spirits (61).

International organizations, such as the CAC, are responding to the aforementioned challenges by imposing new legislation and standards to ensure food safety. Although adherence to the CAC guidelines is not mandatory, as an international organization for standardization, the CAC has played a key role in solving international disputes over the past 50 years (83). The application of international standards does not mean that the same indicator and residue limits are used for a food category, but it involves considering food properties and processing practices according to the standards. Developing countries might find it challenging to follow international standards, but manufacturers or traders who wish to switch from traditional to global business must strictly comply with international standards.

As in the case of MLs, various detection methods are used in different counties, although those of the EU or the AOAC International standards have been adopted by certain countries. To meet the requirements of global economics and harmonized standards, standardized methods and techniques must be used to judge the conformity of spirits. The international standardized test methods must possess favorable characteristics, such as high accuracy, applicability, sensitivity, and repeatability, and the limits of detection must meet the requirements of the MLs set in existing standards. Test results will be considered credible across different counties only when tests are conducted by using appropriate analytical methods and high-quality laboratory facilities and are conducted within the guidelines of the ISO/IEC 17025 “General Requirements for the Competence of Testing and Calibration Laboratories (61).

Standards have played a key role in the management of the most critical risks, but if analyses are limited by a list of target contaminants prepared according to past experience, the risk of overlooking toxic components will increase. Conversely, certain recognized indicators might be not as harmful as expected. Risk assessment performed in combination with toxicological approaches can serve as a gatekeeper for predicting potential risks or confirming the absence of a health concern (61). This is illustrated by the example of formaldehyde, as high concentrations of formaldehyde have been detected in sugarcane spirits (mean content, 4.13 mg/liter) and rum (mean content, 2.42 mg/liter). Monakhova et al. (74) assessed the risk posed to consumers by formaldehyde present in alcoholic beverages, and the result showed that the MOE was >200,000 in the average scenario. Thus, the risk from formaldehyde to the alcohol-consuming population is negligible (74). Lachenmeier et al. (54) compared the risk of carcinogens in alcoholic beverages by using the MOE approach. In the list of investigated components (Table 3), the most important risk factor in alcoholic beverages is ethanol, and there is only a minor risk for other contaminants, such as Pb, arsenic, ethyl carbamate, and acetaldehyde (54). These scientific studies have provided evidence on potential risks for establishing or amending standards.

Potential and emerging hazards from production to consumption (farm to table) must be identified. For example, pesticides were widely used to control insects, weeds, and fungi during the past several decades, when the agricultural production of food accelerated. However, several pesticides are harmful to the environment and humans. Most countries and organizations have established pesticide residue standards for different foods, such as crops, vegetables, fruit, meat, milk, and eggs. Crops, such as cereals, maize, barley, and grapes, are frequently used for producing various spirit drinks, but only a few studies have performed risk assessment for pesticides in spirit drinks. The pesticide transfer ratio to the distillate from the raw material was studied by Cabras et al. (3), who found that only a few pesticides were transferred to the final distilled spirit during the distillation process. Similar results were obtained by Inoue et al. (48) when they analyzed 249 pesticides. Of those pesticides, 89% were not detected in the distillate, and thus the distillation process minimized the risks of pesticides. However, five pesticides (cycloate, cadusafos, diallate, ethoprophos, and thiometon) shared a transfer ratio of >20%, and these compounds might, therefore, pose a risk and be of concern.

Currently, most standards and detection methods are focused on one type of compound. A more comprehensive scope of analysis is required to identify food components and unknown contaminants; the methods used could include metabolomic-like approaches and accurate full-scan mass spectrometry. Risk assessment based on the comprehensive detection method, toxicological information, dietary intake data, and technological measures could provide scientific suggestion for establishing and amending standards in the future. The risk assessment must reflect the risk management needs and be directly applicable to risk management (15).

This article has covered most of the contaminants related to spirit drinks that are included in current standards, although the relevant details differ among various countries and organizations. Notably, some of the mentioned contaminants have received considerable attention, but most countries have not set quality standards related to contaminants, such as ethyl carbamate or phthalate, and this requires further research. Moreover, certain indices used in the standards must be reevaluated based on risk assessment because the potential risk might not be what it is presumed to be, such as in the case of higher alcohols. Harmonization of these requirements and testing methods not only helps avoid trade disputes but also enables an enhancement of the quality and safety of distilled spirits. Risk assessment combined with toxicological approaches is recommended for establishing standards. Furthermore, a more comprehensive scope of analysis will help identify contaminants and avoid potential risks. Improved quality control for raw materials, fermentation, distillation, storage, and equipment will lower the concentration of most contaminants, if all of these measures are implemented effectively and used appropriately.

The authors are grateful for the support from the Project of Specialized Research Fund for the Doctoral Program of Higher Education (20130008110013) and the Beijing Higher Education Young Elite Teacher Project (YETP0310).