2019年臺灣代表性樣本中乙型腎上腺素受體激動劑與飲食習慣之關係探討

Abstract

研究背景：近年由於美牛、萊豬的開放進口，使乙型腎上腺素受體激動劑 (β-adrenergic agonists) 成為廣泛討論的議題。然而，除了美國的萊克多巴胺，乙型腎上腺素受體激動劑在大部分國家皆為違法的飼料添加物，因此不僅是分布情況，針對飲食暴露相關的研究也較少。

研究目的：本研究目的是希望能藉由量測並分析具全國代表性的生物檢體樣本，了解國人整體的暴露分布情況。此外，儘管在過去政府雖然有針對禽畜相關產品制定乙型受體素最大殘留容許量 (maximum residue level, MRL)的相關規範，然而針對肉品中乙型受體素殘留量的檢測並不能反映出國人的實際暴露情形。因此本研究的另一個目的是找出飲食習慣、食物的種類（尤其是肉類產品及其相關加工製品）與乙型受體素檢出率之間的關聯。

材料方法：本研究使用之具全國代表性樣本來自2019年的人體生物監測收案 (Human Biomonitoring, HBM)，母群體為設籍於臺灣本島及澎湖地區七歲以上的居民，參考國民營養健康調查(NAHSIT)的抽樣方法，使用分層、多段與集束取樣法。根據先前的文獻研究，暴露的主要途徑為攝取含有乙型受體素殘留的肉品，且乙型受體素的半衰期短，經由飲食暴露進入人體的乙型受體素平均四小時、最長不超過兩天便會經由尿液及糞便排出體外，雖然在排出時可能伴隨有相對應的代謝物，不過大部分仍會以原型 (parent compounds)存在。因此本研究採用的生物檢體為尿液，尿檢體經由水解、萃取及淨化處理後，使用液相層析串聯質譜儀 (LC/MS/MS)，以常見的八種乙型受體素：萊克多巴胺 (ractopamine)、克倫特羅 (clenbuterol)、特布他林 (terbutaline)、沙丁胺醇 (salbutamol)、希帕特羅 (zilpaterol)、西馬特羅(cimaterol)、妥洛特羅(tulobuterol)和喘必定(fenoterol)作為分析物進行檢測。在統計部分則會將檢測結果和營養及飲食問卷中與禽畜相關產品食用的變項結合，使用費雪精確性檢定(Fisher’s exact test)及羅吉斯迴歸(Logistics regression)進行分析。

研究結果：2019年人體生物監測收案 (Human Biomonitoring, HBM)個案總數為1748位，排除無檢體的個案後可用於後續分析之個案數為1578位。根據費雪精確性檢定的結果顯示，克倫特羅的檢出率明顯高於其他7種乙型受體素，然而不論個案是否有呼吸道相關或是心臟方面相關疾病的用藥，皆不會影響整體乙型受體素的檢出率。8種乙型受體素在性別組別之間分布均勻，不過在年齡組別的部分，18歲以下的族群在克倫特羅的檢出率高於19歲以上的族群，而19-64歲組別的檢出率又高於65歲以上的族群，且這兩種效應皆達到統計上的顯著。在區域分布方面，東部地區的沙丁胺醇檢出率和北部地區的妥洛特羅檢出率均顯著高於其他區域的組別。在飲食習慣對乙型受體素暴露的部分，羅吉斯迴歸分析的結果顯示四足家畜的食用頻率會與克倫特羅的檢出率呈正相關，而肉類製品或其加工產品則會增加妥洛特羅的檢出風險，同樣，內臟的食用亦與妥洛特羅及喘必定的檢出率呈正相關。另一方面，蔬菜的攝取會與特布他林的檢出率呈負相關，意即蔬菜食用頻率較高者，其特布他林檢出的風險反而較低。

結論：乙型受體素的檢出率與某些種類的食物如四足家畜、肉類製品或其加工製品以及內臟呈正相關。然而，我們使用的營養及飲食問卷內容並非針對乙型受體素的來源設計，因此，對於檢出率特別高的克倫特羅，未來可能需要進一步追溯其暴露來源。

Background: Recently, due to the permission of American beef and pork import, β-adrenergic agonists have become a high-profile issue. However, except ractopamine in the United States, β-adrenergic agonists are illegal feed additives in most countries. Hence, there are fewer relative research about not only distribution but dietary exposure.

Objective: This study aimed to establish the distributions of eight types of β-adrenergic agonists among a representative of population in Taiwan. Besides, the detection results of residual β-adrenergic agonists in meat couldn’t represent actual exposure of the population although the government have enacted maximum residue level (MRL) standards of residual β-adrenergic agonists in meat and related products. Therefore, the other objective of this study was to find out the association between the dietary habits (types of food especially meat) and the detection rates of eight types of β-adrenergic agonists.

Material and Methods: The nationwide representative samples used in this study came from Human Biomonitoring (HBM) in 2019. The cases were enrolled from population which residents are over seven years old and registering in the main island of Taiwan and Penghu area, and the sampling methods referred the National Nutrition and Health Survey (NAHSIT) enrollment include stratified, multiple stage and cluster sampling. According to previous studies, the main exposure route was ingestion of meat or related products containing β-adrenergic agonists residues. The half-lives of β-adrenergic agonists were very short. β-adrenergic agonists would be excreted trough urine or feces within two days. Although it might accompany by some corresponding metabolites, most of β-adrenergic agonists still were excreted as their parent compounds. Thus, the chosen specimen was urine. After urine was hydrolyzed, extracted and purified, liquid chromatograph tandem mass spectrometer (LC/MS/MS) would be used to detect eight types of common β-adrenergic agonists as analytes: ractopamine, clenbuterol, terbutaline, salbutamol, zilpaterol, cimaterol, tulobuterol and fenoterol. Then in the statistics part, the detected results would be combined with the variables about poultry-related products ingestion in nutrition and diet questionnaire for analysis by using Fisher’s exact test and Logistics regression.

Results: According to the results of Fisher’s exact test, the detection rate of clenbuterol was much higher than the other seven types of β-adrenergic agonists, and whether the case took respiratory or cardiac medication wouldn’t affect detection rates of the whole population. The distribution of eight types of β-adrenergic agonists in sex group was even. However, the detection rates of clenbuterol in under-18-year-old groups were higher than other groups, and in the 19-64-year-old group, clenbuterol detection rate was higher than that of the group over 65 years old. Then, salbutamol detection rate of eastern group and tulobuterol detection rate of northern group was higher than the other region groups. In terms of exposure of β-adrenergic agonists from dietary habits, the logistics regression analysis results showed that four-footed livestock ingestion frequency positively related to clenbuterol detection rate, and meat product would increase the risk of tulobuterol detection. Similarly, offal ingestion frequency had positive association with detection of tulobuterol and fenoterol. In the other hands, vegetable ingestion and terbutaline detection were negatively correlated.

Conclusions: We found that the detection rates of β-adrenergic agonists were positively associated with some types of foods such as four-footed livestock, meat products and offal. However, the nutrition and dietary habits questionnaire we used wasn’t designed for specific sources of β-adrenergic agonists. Hence, for clenbuterol with a particularly high detection rate, it might need to trace the exposure sources in the future.