類別:

《高齡駕駛人駕駛執照管理制度》對老年人交通事故傷害之影響

2022-11-25T06:34:12Z

標題: 《高齡駕駛人駕駛執照管理制度》對老年人交通事故傷害之影響; Impact of “Elderly Driving License Renewal System” on Traffic Injuries among Elderly Drivers in Taiwan 作者: Yun-Chi Chen; 陳韻淇摘要: 背景：近來高齡駕駛意外頻傳，我國為降低高齡族群死亡人數並提升高齡駕駛安全於民國106年7月1日開始實施《高齡駕駛人駕駛執照管理制度》，針對年滿75歲高齡駕駛提出換照條件，實施對象須體格檢查合格並通過認知功能測試或未患有中度以上失智症才能申請換照，且新申請之駕照有效期限為三年。由於我國建立高齡駕駛人相關政策時間較他國慢且目前我國針對《高齡駕駛人駕駛執照管理制度》進行評估之研究貧乏。因此，本研究目的將分析不同高齡族群於該政策實施前後在性別、受傷程度、主要傷處以及當事者身分別之變化，並評估我國高齡族群於政策實施前後六都與非六都交通事故率、受傷率及死亡率之變化。另外，針對臺北市消防局緊急救護資料分析不同高齡族群於政策前後性別、送醫與否、用路人類別、使用交通工具以及生命體徵等變項之變化。材料與方法：本研究將全國交通事故檔中道路交通事故調查報告表一(BAS)以及道路交通事故調查報告表二(PSN)進行串聯，並依據《高齡駕駛人駕駛執照管理制度》實施日期分為政策前(民國105年7月1日至民國106年6月30日)以及政策後(民國106年7月1日至民國109年6月30日)兩個時間段進行前後比較，首先利用卡方分析(Chi-square)探討65-74歲以及75歲以上高齡族群於該政策實施前後在性別、受傷程度、主要傷處以及當事者身分別四個變項之變化，同時觀察兩個年齡分層之高齡族群於四個變項中是否存在城鄉差異。再將前述串連後之資料結合內政部全球資訊網的各年齡人口數與交通部公路總局提供之汽機車領有駕照人數和汽機車輛登記人數分別計算我國高齡族群以及高齡駕駛族群之交通事故率、受傷率以及死亡率，並於該政策實施前後利用配對T檢定(Paired t-test)分析六都與非六都交通事故率、受傷率以及死亡率之變化。另外，利用臺北市消防局緊急資料庫進行卡方分析(Chi-square)以研究臺北市兩個年齡分層之高齡族群於政策前(民國104年7月1日至民國106年6月30日)以及政策後(民國106年7月1日至民國109年6月30日)在性別、送醫與否、用路人類別、使用交通工具之變化，並觀察不同年齡分層之高齡族群政策前後在意識狀態、GCS以及血氧濃度等生命體徵變項之變化。結果：本研究觀察我國交通事故檔資料中高齡族群發生交通事故時的特性，結果發現政策實施前年齡為75歲以上高齡族群相比於65-74歲高齡族群發生交通事故時在性別為男性的比例、受傷程度為受傷以及死亡的比例、主要傷處為頭部、當事者身分別為自行車、行人以及乘客的比例皆顯著較高(p<0.001)。而政策實施後全國75歲以上高齡駕駛族群之交通事故率、受傷率以及死亡率有顯著下降(p<0.05)，非六都高齡駕駛族群之交通事故率以及受傷率也有顯著下降(p<0.05)，六都高齡駕駛族群則只有死亡率有顯著下降(p<0.05)。另外，針對臺北市緊急救護資料分析結果，發現政策實施前75歲以上高齡駕駛族群發生交通事故時送醫的比例與65-74歲高齡駕駛族群的比例沒有顯著差異，但在政策實施後75歲以上高齡駕駛族群發生交通事故時送醫的比例(82.72%)則顯著低於65-74歲高齡駕駛族群發生交通事故時送醫的比例(86.74%)。政策實施前75歲以上高齡駕駛族群發生交通事故時GCS=15的比例(99.33%)顯著高於65-74歲高齡駕駛族群發生交通事故時GCS=15的比例(98.11%)，但在政策實施後75歲以上以及65-74歲高齡駕駛族群卻沒有顯著差異。而政策實施前75歲以上高齡駕駛族群血氧濃度>=98%的比例與65-74歲高齡駕駛族群的比例沒有顯著差異，但在政策實施後75歲以上高齡駕駛族群血氧濃度>=98%的比例(65.01%)卻顯著低於65-74歲高齡駕駛族群的比例(68.74%)。另外，65-74歲以及75歲以上高齡駕駛族群在政策實施前後於性別、意識狀態以及交通方式則沒有顯著差異。結論：本研究依據現有的資料提出以下幾個論點。第一，我國高齡族群發生交通事故時以男性、受傷、主要傷處為頭部居多，而在當事者身分別上可以看到65-74歲的高齡族群發生交通事故時以汽車及機車為主，75歲以上的高齡族群則以機車及行人為主。第二，本研究觀察到《高齡駕駛人駕駛執照管理制度》實施後六都地區高齡駕駛族群的死亡率有下降的趨勢，但在非六都地區高齡駕駛族群則沒有下降的趨勢。第三，本研究發現75歲以上之高齡駕駛族群相比於65-74歲高齡駕駛族群在送醫的比例上有顯著下降的趨勢。然而《高齡駕駛人駕駛執照管理制度》實施剛屆滿三年推廣期，對於我國高齡駕駛族群的影響則仍需長期以評估政策的實際成效。

馬達產生之微粒排放特性

2024-08-29T16:09:33Z

標題: 馬達產生之微粒排放特性; The Characteristic of Aerosol Emission from Motors 作者: 許兆鈞; Chao-Chun Hsu 摘要: 家用電器內的馬達是生活中最常見的驅動器之一，其功能是將電力轉為機械力，藉此驅動風扇或是特定的設備，然近年來越來越多研究顯示，安裝於室內電器的微型馬達，能觀察到微粒的產生，這些細小微粒容易被人體吸入，並且沉積在支氣管或是肺部等區域，對於人體的健康有很大的疑慮。而家用電器運作時距離人體很近，容易造成更高的暴露危害，因此需要對馬達產生的微粒進行評估，而過去的研究報告所提供之資訊僅能凸顯馬達確實是重要的微粒產生源，卻未有量測馬達產生微粒的標準方法，因此本研究會先建立方法以評估馬達在不同參數下的微粒的產生特性，並探討馬達微粒產生的機制，提出解決馬達微粒排放問題的策略。本研究首先會先建置一實驗系統，使用數顆同一廠牌的直流有刷馬達以及直流無刷馬達進行實驗，並以實驗確認微粒量測的準確度且能完整的量測馬達所產生的微粒數目，再藉由改變各項參數了解對馬達微粒排放的影響。微粒產生機制的確認則是使用相同型號的馬達(Motor2)來帶動待測馬達(Motor1)，希望透過主動運轉(供電給Motor1)及被動運轉(供電給Motor2)來區分火花放電以及機械磨損這兩種馬達產生微粒的主要機制，並以電子顯微鏡觀察馬達所產生的形狀及成分。最後量測市售電動刮鬍刀所產生的微粒特性。為了解系統所需的稀釋流量，測試了在不同轉速下稀釋流量對馬達產生微粒濃度的影響，再計算馬達每秒的微粒產生率來評估是否能量測到所有馬達產生的微粒。結果表明，直流有刷馬達產生的微粒排放率會隨著稀釋流量提高而提升，當稀釋流率大於10 L/min後趨於穩定，並將系統的稀釋流率訂為12 L/min。針對直流有刷馬達產生微粒兩種可能機制分別是火花放電以及機械摩擦進行探討，研究結果指出火花放電是馬達產生微粒的主要原因，經由火花放電產生的微粒數目每秒約為2.1*107顆約為機械摩擦產生的250倍，粒徑落在40 nm，同時量測了直流無刷馬達的微粒產生率與粒徑，結果表明直流無刷馬達每秒依舊會產生2.2*104顆微粒，約為直流有刷馬達產生的微粒的千分之一，粒徑約為120 nm，且直流有刷馬達以及直流無刷馬達的微粒產生率皆會因為轉速提高而上升，在電動刮鬍刀的實驗中也驗證了轉速提高會影響產生的微粒數目濃度，此外亦發現防水的外殼可以有效的減少馬達產生的微粒逸散。; Motors in household appliances are among the most common actuators in daily life, converting electrical energy into mechanical force to drive fans or specific devices. However, recent studies have shown that miniature motors installed in indoor appliances can generate particles. These fine particles are easily inhaled and can deposit in the bronchi or lungs, raising significant health concerns. Since household appliances operate close to the human body, the risk of exposure is higher, necessitating an evaluation of the particles generated by these motors. Previous research has highlighted that motors are indeed significant sources of particle emissions but has not provided a standard method for measuring these emissions. Therefore, this study aims to establish a method to evaluate the particle generation characteristics of motors under different parameters, investigate the mechanisms of motor particle generation, and propose strategies to mitigate particle emissions from motors. This study will first establish an experimental system using several DC brushed motors and DC brushless motors from the same manufacturer. The experiments will verify the accuracy of particle measurements and ensure a comprehensive assessment of the number of particles generated by the motors. By varying different parameters, we aim to understand their impact on motor particle emissions. To confirm the particle generation mechanisms, we will use an identical model motor (Motor2) to drive the test motor (Motor1). By comparing active operation (powering Motor1) and passive operation (powering Motor2), we hope to distinguish between spark discharge and mechanical wear as the primary mechanisms of particle generation. An electron microscope will be used to observe the shape and composition of the particles generated by the motors. Finally, we will measure the particle characteristics produced by commercially available electric shavers to validate the experimental results. To determine the necessary dilution flow rate for the system, we tested the impact of dilution flow rates on particle concentrations generated by the motor at different speeds. We then calculated the particle generation rate per second to evaluate whether all particles produced by the motor could be measured. The results showed that the particle emission rate of the DC brushed motor increases with higher dilution flow rates and stabilizes when the flow rate exceeds 10 L/min. Consequently, we set the system's dilution flow rate to 12 L/min. We explored the two potential mechanisms of particle generation in DC brushed motors: spark discharge and mechanical friction. The study results indicated that spark discharge is the primary cause of particle generation. Particles generated by spark discharge amount to approximately 2.1 x 107 particles per second, about 250 times the number produced by mechanical friction, with a particle size of around 40 nm. We also measured the particle generation rate and size for DC brushless motors. The results show that DC brushless motors still produce particles, generating about 2.2 x 104 particles per second, which is roughly one-thousandth of the particle count generated by DC brushed motors, with a particle size of around 120 nm. The particle generation rates for both DC brushed and brushless motors increase with higher speeds. In experiments with electric shavers, we confirmed that increasing the speed affects the particle concentration. Additionally, we found that a waterproof casing can effectively reduce the dispersion of particles generated by the motor.

馬桶沖水過程中微粒產生的評估與控制

2024-08-26T16:18:13Z

標題: 馬桶沖水過程中微粒產生的評估與控制; Evaluation and Control of Aerosol Emission from Toilet Flushing 作者: 許順皓; Shun-Hao Hsu 摘要: 一款設計不良的馬桶可能成為疫情傳播的助手。在SARS、COVID-19疫情爆發前，呼吸道傳染病常被認為主要藉由咳嗽、打噴嚏、呼吸及說話方式進行傳播，隨著許多研究證明了馬桶能在沖水過程中將病原體氣膠化後，有關馬桶與呼吸道傳染病間的關係才逐漸受到重視，然而，目前多數的研究主要以馬桶產生微粒之特性、影響微粒產生的因子以及所產生微粒與傳染病間的關係進行探討，反而較少針對產生源與相關控制手段進行探討，因此，本研究以職業衛生的基本工作，評估與控制馬桶逸散微粒的問題，在現有馬桶的基礎之下，透過調整影響微粒產生的參數與加裝微粒防制設備，來減少微粒的逸散，並降低使用馬桶後暴露於疾病的風險。由於目前尚未有一套統一量測馬桶產生微粒的方法，在實驗上，本研究於一般室內環境中建立一套不受背景微粒干擾且能快速量測市售馬桶微粒排放與逸散的方法。在量測上，本研究使用自來水重複進行沖洗，並以沖水所產生的液滴微粒特性進一步探討。而在量測微粒的基本特性上，使用光學式粒徑分析儀與凝結式微粒計數器分別量測0.3～10 μm微粒之粒徑濃度分布，以及小於1 μm微粒之總微粒數。而本研究主要針對市售六款馬桶進行測量，並探討不同沖洗參數(沖水量、水流方式、沖洗時間、沖洗機制)條件下對於微粒逸散的影響，接著會針對目前市售馬桶清潔產品對於微粒排放的影響進行評估。在量測完微粒的基本排放特性後，針對市售馬桶蓋與脫臭馬桶蓋進行量測與探討(馬桶蓋的效果、抽氣流量的影響)，最後藉由將一系列測試(抽氣流量、氣罩外型、抽氣面積)所收集到的參數整理後，將市售馬桶蓋進行改良並探討其效果。結果顯示，沖水後馬桶產生微粒的主要過程是沖水時，由於水柱撞擊液面後導致大量空氣與水在快速混合後產生大量的氣泡破裂，進而有大量的液滴微粒產生；目前市售馬桶在單次沖洗所排放的微粒量上皆落在105 #/Flush，並且會受到不同的沖洗條件(水量、沖洗能量、入水角度)而有所影響；在微粒的基本特性上，乾燥微粒的中位數粒徑為0.2 μm、初始液滴的中位粒徑為2.84 μm；在馬桶清潔劑的使用上則會增加液滴微粒的排放量；而市售馬桶蓋在防止微粒逸散上約有85%的效果，其主要原因在於馬桶蓋與馬桶座間存在間隙問題，導致微粒能逸散環境；而市售抽氣脫臭馬桶蓋因為所使用的活性碳濾材無法補集沖水時所產生的微粒，反而會導致馬桶盆內的微粒快速逸散至環境。最後，經過一系列的測試後，目前共研發兩款有效控制微粒逸散的馬桶蓋原型，並且皆能在沖水後1.5分鐘內有效移除99%殘留於馬桶盆內的微粒。因此，就研究結果可發現，在微粒逸散上，運用工程控制的角度，針對沖水所產生的微粒進行主動式收集，能有效解決微粒逸散至環境的問題；而在未來的馬桶設計上，若能有效防止沖水過程中大量氣泡的產生，將能根本減少液滴微粒的形成。; A poorly designed toilet may facilitate the spread of epidemics. After the outbreak of SARS and COVID-19, numerous studies have demonstrated that toilets can aerosolize pathogens during flushing. Nevertheless, most existing research is more focused on the characteristics of particles, the influence factors of particle generation, and the relationship between the particles and infectious diseases. In contrast, fewer studies used source control or engineering control to decrease particle generation. Therefore, this study aims to experimentally investigate the particle characteristics, generation mechanisms, and influencing factors of droplet particles generated by various flushing toilets. Then, design and evaluate methods that can eliminate the generation or emission of droplet particles from toilets. Due to the lack of a standardized method for measuring particles generated by toilet flushing. This study established a method without interference from background particles and could rapidly measure particles generated from toilet flushing and evaluate the effectiveness of toilet lids in preventing particle leakage. This study used tap water for repeated flushing and further discussed the characteristics of droplet particles generated from toilet flushing. To measure the basic characteristics of particles, a Condensation Particle Counter and an Optical Particle Sizer were used to monitor the particle size distribution in the size range of 0.3～10 μm and the total count of particles with diameters less than 1 μm, respectively. This study used six commercial toilets to measure and discuss the effects of different flushing parameters (flush volume, angle of water entry into the bowl, flush duration, flushing mechanism) on particle generation. Then, the impact of commercial toilet cleaning products on particle generation, and the effectiveness of preventive particle leakage on the commercial toilet lid were also assessed and discussed. Finally, some parameters would be collected from a series of tests (exhaust airflow, hood shape, exhaust area), and these parameters would be used to modify the commercial toilet lids and then evaluate their effectiveness. The results indicated that the primary particle generation process during toilet flushing was the rapid mixing of air and water inside the toilet bowl, and it would produce a large number of bubble bursts and droplet particles. The count of particles generated from commercial toilets was about 10⁵ #/flush and would be affected by different flushing conditions (water volume, flushing energy, and water entry angle). The count median diameter of particles and initial droplets was 0.2 μm and 2.84 μm. The toilet bowl cleaner would increase the generation of droplet particles. The commercial toilet lids could provide 85% effectiveness in preventing particle leakage from toilet bowl. However, there were gaps between the toilet lid and seat, resulted in particles leakage into the environment. For deodorizing toilet lids, particles could rapidly leaked into the environment because the activated carbon could not capture particles generated during flushing. Finally, two prototype toilet lids were developed, and both could effectively remove 99% of particles remaining in the toilet bowl within 1.5 minutes after flushing. Therefore, using engineering controls to actively collect the particles generated during flushing can effectively address the issue of particle emission into the environment. For future toilet designs, it can fundamentally reduce the generation of droplet particles by effectively preventing the generation of large bubbles during the flushing process.

飼料中的PFOS與PFOA之健康風險評估

2024-08-28T16:19:19Z

標題: 飼料中的PFOS與PFOA之健康風險評估; Health Risk Assessment on PFOS & PFOA in animal feed 作者: 陳沛宜; Pei-Yi Chen 摘要: 全氟與多氟烷基物質（Per- and polyfluoroalkyl substances , PFASs），具有抗水、抗油和耐高溫的特性，被廣泛應用於消防泡沫、食品包裝和個人護理用品等，並在環境中無處不在。多種PFASs被認為是致癌物，並具有生殖毒性與發育毒性，由於其在各種環境介質中的持久性和生物累積性，其潛在的健康影響備受關注。在各種PFAS暴露途徑（exposure scenarios）中，經由日常食用肉類和動物源性產品而間接暴露於動物飼料中的PFASs尚未得到研究，但這對於傳統上經常食用養殖動物內臟的臺灣人群和亞洲國家居民尤為關鍵。目前，轉移因子（Transfer factor, TF）和基於生理學的毒物動力學（physiologically based toxicokinetics, PBTK）模型已被用來估算從飼料轉移到動物組織中的危害，但由於其複雜性和高不確定性，缺乏對動物群體個體差異的考慮，並未被廣泛使用。為了解決這些問題，本研究旨在以全氟辛酸（Perfluorooctanoic acid, PFOA）和全氟辛烷磺酸（Perfluorooctane sulfonic acid, PFOS）為例，通過貝氏統計（Bayesian statistics）方法建立其在動物組織中的濃度與飼料中濃度的關係，以此進行健康風險評估，並提出飼料中PFOA和PFOS的最大限量（maximum limits, MLs），評估結果將可提供我國政府與國際間作為制定飼料中PFOS 與 PFOA 殘留標準之參考。我們建立了用於評估危害物質從飼料到動物轉移的框架，該框架能夠根據半衰期和飼養期去選擇合適的計算方法，不僅考量了物種間和物種內的差異，同時也較容易上手，可用於數據有限的情況。在這個框架下，我們首先比較動物飼養期和化合物於動物體內的半衰期的長短，接著建立單室藥代動力學模型，求解後以泰勒級數（Tayor’s series）展開，由此獲得短半衰期化合物的轉移因子，長半衰期化合物的線性和時間依賴（time dependent）的轉移因子，介於兩者之間的其餘化合物，則將使用毒物動力學推導而來的公式，以估算這些動物在食入受PFOS 和 PFOA 汙染後，PFASs 在動物組織與器官的分布。針對短半衰期化合物和長半衰期化合物，我們收集了牛、羊、豬、雞的 PFOS 和 PFOA之轉移數據，作為貝氏統計建模的先驗信息，以估算這些五種家禽和家畜中轉移因子和殘留濃度的後驗分佈；並蒐集介於兩者之間的化合物，蒐集其生理參數、半衰期與動物實驗數據等，使用蒙地卡羅模擬進行殘留濃度的估計。最後，使用國家攝食資料庫（National Food Consumption Database）中的肉類和內臟攝食量（consumption rates），結合各動物群體組織中的PFOS和PFOA殘留濃度分佈情形，進行機率健康風險評估（probabilistic risk assessment）。我們假設動物在整個飼養期內，每天皆暴露於含有1 μg/kg PFOA/PFOS的動物飼料，估算了殘留濃度，PFOS 部分，殘留濃度估計值由高至低依序為豬肝、豬腎、牛肝、羊肝、雞蛋、鴨肝、其他豬內臟、羊腎等；PFOA 則依序為：豬腎、豬肝、雞蛋、其他雞內臟。這些數據進一步用於機率風險評估。我們以蒙地卡羅模擬進行10,000次試驗（10,000 trials），評估在 General public和 Consumer only下，臺灣各年齡組的平均每日攝取劑量（Average daily intyake , ADD）和終生平均每天暴露劑量（Lifetime average daily dose, LADD），並計算危害商數（Hazard quotient, HQ），以提出 MLs 建議值。我們提出的飼料 MLs如下：PFOS 為 2.1×10^(-4) 至 2.6×10^(-3) μg∕kg，PFOA 為 2×10^(-4) 至 2.2 ×10^(-3) μg∕kg，這遠低於當前已有文獻記載的飼料濃度，其顯示當前的飼料濃度對人類的間接暴露存在健康風險。然而，這也遠低於當前的偵測與定量限，因此未來應增進飼料中微量物質分析之能力，並制定飼料之PFOS 與 PFOA之限量基準，以維護國人健康。; Per- and polyfluoroalkyl substances (PFASs), resistant to water, oil, and temperature, are widely applied in industries like the production of firefighting foams, food packaging, and personal care items and ubiquitous in environment. Several PFASs are carcinogens and reproductive and developmental toxicants and their potential health effects have been of great concerns due to their persistence and bioaccumulation in various environmental media. Among the various scenarios of PFAS exposures, the indirect exposures to PFASs in animal feed via daily consumption of meats and animal products have not been assessed, but particularly critical for the Taiwanese populations and people in Asia countries, traditionally consuming offal of farmed animals. Currently, the transfer factor (TF) and physiologically-based Toxicokinetics (PBTK) have been used to estimate hazard residues in tissues of animals transferred from feed. But, the former lacks theoretic basis and conditions of utilization, and the later lacks consideration of inter-individual differences in an animal population and are not popular with its complexity and high uncertainty. To improve the current methods, the objective of this study is to use PFOA and PFOS as examples to establish the relationships of their concentrations in the tissues of animals with those in feed using Bayesian statistics for health risk assessment and to propose maximum limits (MLs) of PFOA and PFOS in feed. These results will provide a valuable reference for the Taiwanese government and international regulatory agencies in establishing standards for PFOS and PFOA residues in animal feed. We developed a framework for estimating the residual concentration of a hazard in tissues of farmed animals transferred from feed, which features: easy to use, an appropriate method selected by using half life and feeding period, suitable for cases with limited data, with considering inter- and intra-species variability. Under this framework, an one-compartment pharmacokinetics will be formulated, solved, and expanded with the Tayor’s series to obtain a TF for a short-half-life compound and linear and time-dependent TF for a long-half-life compound compared with animal feeding periods. For compounds with intermediate half-lives, we used pharmacokinetic-derived formulas to estimate the distribution of PFASs in animal tissues and organs after ingestion of PFOS and PFOA-contaminated feed. For short- and long-half-life compounds, TF data of PFOS and PFOA in cattle, sheep, pigs, hens, ducks (Only PFOS) will be cited to serve as prior information for Bayesian statistical modeling to estimate the posterior distributions of their TFs and residues in tissues of these poultry and livestock; For intermediate-half-live compounds, we collected physiological parameters, half-life data, and animal experiment data to estimate residue concentrations using Monte Carlo simulations. The distributions of meat and offal consumption rates are cited from the National Food Consumption Database and used to probabilistically assess health risk with the distributions of PFOS and PFOA residues in tissues of each animal population. We assumed that animals were exposed daily to feed containing 1 μg/kg of PFOA/PFOS throughout the feeding period and estimated the residue concentrations. For PFOS, the estimated residue concentrations from highest to lowest were pig liver, pig kidney, cattle liver, sheep liver, chicken eggs, duck liver, other pig organs, and sheep kidney. For PFOA, they were pig kidney, pig liver, chicken eggs, and other chicken organs in that order. According to our assessment, the HQs for different age groups under general public and consumer only in Taiwan are based to propose MLs in feed: PFOS ranges from 2.1×〖10〗^(-4) to 2.6×10^(-3) μg/kg, and PFOA ranges from 2×10^(-4) to 2.2 ×10^(-3) μg/kg. These levels are much lower than the current PFOS and PFOA levels in feed, indicating potential health concerns due to indirect human exposures to both compounds in feed. Moreover, these levels are also much lower than current detection and quantification limits, and advanced analytical methods with sufficient sensitivity are needed for trace analysis of them in animal feed to ensure that the newly-revised standards of PFOS and PFOA in feed can be enforced to protect public health.