📚 Risk Assessment in Biological Investigations | 生物实验中的风险评估
Risk assessment is a fundamental skill in A-Level Biology practical work. It involves systematically identifying hazards, evaluating the chance and severity of harm, and implementing measures to minimise risk. Mastering risk assessment not only ensures safety but also strengthens experimental design, a key competency examined throughout the Cambridge International syllabus. This article explores the principles and applications of risk assessment in biological investigations, from handling corrosive chemicals to fieldwork in delicate ecosystems.
风险评估是A-Level生物实验操作中的一项基本技能。它系统性地识别危险源、评估危害发生的概率与严重程度，并实施降低风险的措施。掌握风险评估不仅能保障安全，还能强化实验设计能力——这是剑桥国际大纲始终关注的核心素养。本文将从腐蚀性化学品的取用到脆弱生态系统的野外工作，探讨风险评估在生物探究中的原理与应用。
1. Defining Risk Assessment | 风险评估的定义
Risk assessment is the process of systematically examining what could cause harm in a practical activity, so that appropriate precautions can be taken. In biology, this goes beyond simply listing hazards — it requires an understanding of how biological agents, apparatus and procedures interact to create potential incidents. A well-structured assessment distinguishes between a hazard (something with the potential to cause harm) and a risk (the likelihood of that harm occurring).
风险评估是系统检查实验活动中可能导致伤害的因素，以便采取适当预防措施的过程。在生物学中，这不仅仅是罗列危险源——它需要理解生物制剂、仪器和操作流程如何相互作用，从而产生潜在事故。一份条理清晰的评估会区分危险源（具有潜在危害的事物）与风险（该危害发生的可能性）。
For example, a hot water bath is a hazard because it can burn skin; the risk increases if the bath is placed near the edge of a bench or if students reach over it carelessly. Cambridge practical assessments expect candidates to recognise that risk changes with context, such as the concentration of a chemical or the duration of exposure, and to demonstrate this in their planning.
例如，热水浴是一个危险源，因为它可能烫伤皮肤；若水浴靠近实验台边缘或学生不经意从其上方伸手跨越，风险便会增大。剑桥的实践评估期望考生认识到风险随场景变化——如化学品浓度或暴露时长——并在实验规划中体现这一点。
2. Identifying Hazards in the Lab | 实验室中的危险识别
Hazard identification is the first critical step. In a biology laboratory, hazards can be grouped into categories: biological (microorganisms, allergens), chemical (irritants, toxins, corrosives), and physical (hot surfaces, sharp instruments, electrical equipment). A systematic walk-through of the procedure, from preparation to disposal, helps uncover hazards that may otherwise be overlooked, such as contamination of sterile workspaces or aerosol formation when pipetting.
危险识别是关键的第一步。在生物实验室中，危险源可分为类别：生物性（微生物、过敏原）、化学性（刺激物、毒素、腐蚀物）和物理性（热表面、尖锐器械、电器设备）。从准备到废弃处理，系统地预演实验步骤有助于发现可能被忽视的风险，例如无菌工作区的污染或移液时产生的气溶胶。
Cambridge International often tests hazard identification in the context of enzyme experiments, DNA electrophoresis, or microscopy. Students must be able to list specific hazards: for instance, the use of Benedict's reagent involves hot alkaline copper sulfate, which is both corrosive and a thermal hazard. Recognising that a single substance can pose multiple hazards is essential for thorough risk assessment.
剑桥国际考试常在酶学实验、DNA电泳或显微观察的情境中考查危险识别。学生必须能够列出具体的危险源：例如，使用本尼迪克特试剂涉及热的碱性硫酸铜，这既是腐蚀性危害又是热危害。认识到一种物质可能带来多重危害，对全面风险评估至关重要。
3. Evaluating Severity and Likelihood | 评估严重性和可能性
Once hazards are identified, the next stage is to gauge both the severity of potential harm and the likelihood of occurrence. A simple risk matrix can be used, where severity (negligible, minor, moderate, major, severe) is plotted against likelihood (rare, unlikely, possible, likely, almost certain). The resulting score helps prioritise control measures.
一旦识别出危险源，下一步就是评估潜在伤害的严重程度和发生的可能性。可以使用一个简单的风险矩阵，将严重性（可忽略、轻度、中度、重大、严重）与可能性（罕见、不大可能、可能、很可能、几乎确定）相交。得出的风险分值有助于确定控制措施的优先级。
| Severity ↓ / Likelihood → | Rare | Unlikely | Possible | Likely | Almost Certain |
| Severe | Medium | High | High | Extreme | Extreme |
| Major | Low | Medium | High | High | Extreme |
| Moderate | Low | Low | Medium | Medium | High |
| Minor | Very low | Low | Low | Medium | Medium |
| Negligible | Insignificant | Very low | Very low | Low | Low |
In a typical biology investigation, such as extracting DNA using ethanol, ethanol is highly flammable and the protocol often involves a water bath at 60 °C. The likelihood of ignition may be low if open flames are absent, but the severity of a fire would be extreme. Therefore, the overall risk is rated as medium to high and requires strong controls, like working away from ignition sources and using small volumes.
在典型的生物探究中，例如使用乙醇提取DNA，乙醇极易燃烧，且实验方案通常涉及60 °C的水浴。若没有明火，着火的可能性较低，但火灾的严重程度是极端的。因此，总风险评级为中等到高，需要强有力的控制措施，如远离点火源并使用少量乙醇。
4. The Hierarchy of Control Measures | 控制措施的分级
Control measures should follow a hierarchy from most to least effective: elimination, substitution, engineering controls, administrative controls, and personal protective equipment (PPE). In biology, elimination might mean deciding not to use a highly pathogenic microorganism; substitution could involve replacing a toxic stain with a safer alternative, such as using methylene blue instead of ethidium bromide for DNA visualisation where possible.
控制措施应遵循从最有效到最无效的层次：消除、替代、工程控制、行政控制和个人防护装备（PPE）。在生物学中，消除可能指决定不使用高效病性的微生物；替代则可能涉及用更安全的染色剂代替有毒染料，比如在可能的情况下用亚甲蓝替代溴化乙锭进行DNA显色。
Engineering controls include fume hoods, biosafety cabinets, and sealed centrifuge rotors. Administrative controls involve standard operating procedures, training, and restricted access. Only after these are in place should PPE, such as lab coats, gloves, and goggles, be relied upon. Cambridge exams often ask students to justify the choice of control measures with reference to this hierarchy.
工程控制包括通风橱、生物安全柜和密封的离心机转子。行政控制涉及标准操作规程、培训和限制进入。只有在这些措施到位后，才能依赖PPE，例如实验服、手套和护目镜。剑桥考试经常要求学生参照这一分级体系，说明选择具体控制措施的理由。
5. Biological Hazards: Microbes and Enzymes | 生物危害：微生物和酶
Handling microorganisms requires careful risk assessment because of potential pathogenicity, allergenicity, and the ability to produce toxins. Even non-pathogenic organisms, such as Saccharomyces cerevisiae, can become opportunistic pathogens in immunocompromised individuals. Aseptic technique is not only a method to avoid contamination of cultures but also a key control measure to prevent exposure to aerosols or spills.
操作微生物需要谨慎的风险评估，因为其具有潜在的致病性、致敏性和产生毒素的能力。即使是非致病性生物，如酿酒酵母，也可能在免疫功能低下者中成为条件致病菌。无菌操作不仅是避免培养物污染的方法，也是防止接触气溶胶或溢洒物的关键控制措施。
Allergens represent a subtler hazard. Repeated exposure to enzymes like amylase or protease in powder form can lead to respiratory sensitisation. Therefore, practicals often use pre-prepared enzyme solutions rather than allowing students to weigh out dry powder, and work should be conducted in well-ventilated areas or fume hoods. Risk assessments must also account for the disposal of biological waste, typically by autoclaving or chemical disinfection before disposal.
过敏原是一种较为隐蔽的危害。反复接触粉末形式的淀粉酶或蛋白酶等酶类可能导致呼吸道致敏。因此，实验通常使用预先配制的酶溶液，而不允许学生称量干粉，并且应在通风良好的区域或通风橱中操作。风险评估还必须考虑到生物废物的处置，通常需在废弃前进行高压灭菌或化学消毒。
6. Chemical Hazards: Corrosives and Toxins | 化学危害：腐蚀物和毒素
Many reagents in biology carry chemical hazards. Benedict's solution contains sodium carbonate and copper(II) sulfate; upon heating it becomes caustic and can cause burns. Iodine solution, though dilute, is toxic to aquatic life and can stain skin. The risk assessment must consider concentration, volume, and the nature of exposure — for example, whether a chemical is likely to splash during mixing or heating.
生物实验中许多试剂具有化学危害。本尼迪克特溶液含有碳酸钠和硫酸铜（II）；加热后具有腐蚀性，可导致灼伤。碘液尽管稀释，对水生生物有毒并会染色皮肤。风险评估必须考虑浓度、体积以及暴露的性质——例如，试剂在混合或加热时是否会飞溅。
For organic solvents like ethanol and acetone, flammability and volatility are primary concerns; vapour accumulation can lead to flash fires. Buffers used in gel electrophoresis, such as TBE, may contain boric acid and EDTA, which are irritants. The hazard classification symbols (GHS pictograms) should be clearly understood and referenced in the assessment. Students need to know where to find safety data sheets (SDS) and how to interpret them.
对于乙醇和丙酮等有机溶剂，易燃性和挥发性是主要关切；蒸气积聚可能导致爆燃。凝胶电泳中使用的缓冲液，如TBE，可能含有硼酸和EDTA，均为刺激物。应清楚理解危害分类符号（GHS象形图），并在评估中引用。学生需要知道如何获取安全数据表（SDS）并解读其内容。
7. Physical Hazards: Heat, Sharps and Electrophoresis | 物理危害：热源、尖锐物和电泳
Physical hazards are sometimes underestimated. Water baths, hot plates, and Bunsen burners all present burn risks. Sharps, such as dissection scissors, scalpels, and glass Pasteur pipettes, can cause cuts. The risk is elevated when such instruments are used under time pressure or by students with limited dexterity.
物理危害有时会被低估。水浴、电热板和本生灯都有烫伤风险。尖锐器械，如解剖剪、手术刀和玻璃巴斯德吸管可能造成割伤。当学生时间紧迫或操作不够灵巧时，风险会进一步升高。
Electrophoresis tanks pose a unique physical hazard: the combination of high voltage (typically 100-150 V) and conductive buffer can cause electric shock. Risk control includes checking for frayed wires, never operating with wet hands, and using lids with safety interlocks. Centrifuges must be balanced correctly to avoid rotor damage and possible injury from dislodged tubes.
电泳槽带来独特的物理危害：高电压（通常100-150 V）和导电缓冲液的组合可引起电击。风险控制包括检查电线有无磨损、绝不用湿手操作，以及使用带安全联锁的盖子。离心机必须正确平衡，以避免转子损坏和由离心管移位造成的潜在伤害。
8. Fieldwork and Environmental Sampling | 野外工作和环境采样
Ecological investigations take risk assessment beyond the laboratory. Terrain, weather, water bodies, and wildlife introduce hazards that are harder to control. Slipping on wet rocks, encountering poisonous plants like giant hogweed, or exposure to tick-borne Lyme disease are all realistic concerns. Moreover, sampling techniques such as kick-sampling in streams require awareness of water depth and flow rate.
生态学调查将风险评估带出实验室。地形、天气、水体和野生生物引入了更难控制的危险源。在湿滑的岩石上滑倒、碰到大猪草等有毒植物，或遭受蜱传莱姆病的暴露，都是现实的担忧。此外，像溪流踢网采样这样的技术，需要掌握水深和流速的意识。
Fieldwork risk assessments should include emergency procedures, communication plans, and first-aid provisions. It is also vital to assess the risk that the investigation poses to the environment — disturbing fragile habitats, trampling vegetation, or introducing invasive species via uncleaned boots or equipment.
野外工作风险评估应包括应急程序、通信计划和急救用品。同时，评估调查对环境本身的风险也至关重要——如干扰脆弱栖息地、踩踏植被，或通过未清洁的靴子和设备引入入侵物种。
9. Genetically Modified Organisms (GMOs) | 转基因生物
Experiments involving genetic modification, often carried out in well-equipped sixth-form labs, demand rigorous risk assessment. The host organism (e.g., E. coli strain K-12) is generally disabled and non-pathogenic, but the introduction of antibiotic resistance genes requires caution. Contained use regulations require that GMOs are not released into the environment, meaning all cultures, plates, and pipette tips must be autoclaved before disposal.
涉及基因改造的实验，常在设施完善的高中实验室中进行，需要进行严格的风险评估。宿主生物（如大肠杆菌 K-12 菌株）通常已削弱、无致病性，但引入抗生素抗性基因需谨慎。受控使用法规要求转基因生物不得释放到环境中，这意味着所有培养物、平板和吸头都必须在处置前高压灭菌。
The risk assessment must also consider horizontal gene transfer and the potential for creating resistant bacteria beyond the laboratory. Although the probability is extremely low with disabled strains, good microbiological practices are non-negotiable. Cambridge practical tasks involving transformation typically demand that students justify their containment strategy.
风险评估还必须考虑横向基因转移以及在实验室外产生耐药细菌的可能性。尽管使用削弱菌株时此概率极低，但良好的微生物规范是不可妥协的。剑桥的转化实验任务通常要求学生说明其围堵策略的理由。
10. Risk Assessment Documentation and Checklists | 风险评估文档和检查表
ate, identified hazards, persons at risk, existing controls, risk rating (likelihood × severity), and further actions needed. Many schools use a simple checklist approach, but Cambridge encourages students to develop their own logical structure.
在开始任何实验操作前，书面风险评估往往是必须的。典型的模板包括：活动名称、实验室位置、日期、已识别的危险源、受影响人员、现行控制措施、风险评级（可能性×严重性），以及需采取的进一步行动。许多学校采用简单的检查表方式，但剑桥鼓励学生自主构建条理清晰的评估结构。
Effective documentation is not a bureaucratic exercise — it helps students internalise the safety thinking. For example, before starting an investigation into the effect of temperature on membrane permeability using beetroot, candidates should write down hazards (scalding water, broken glass cuvettes, beetroot juice splashes) and corresponding controls. This record also provides evidence of progress in the practical endorsement.
有效记录并非形式主义——它帮助学生内化安全思维。例如，在开始使用甜菜根探究温度对膜通透性影响之前，考生应写下危险源（烫伤的热水、碎裂的玻璃比色皿、甜菜汁飞溅）及相应的控制措施。这些记录也为实验操作认可提供了佐证。
11. Ethics, Consent and Animal Use | 伦理、知情同意和动物使用
When investigations involve human participants, such as measuring heart rate response to exercise, ethical risk assessment becomes essential. Risks are not only physical but also psychological — participants may feel discomfort or embarrassment. Informed consent must be obtained, and participants should be able to withdraw at any time. Confidentiality of personal data is a further ethical requirement.
当探究涉及人类参与者，例如测量运动对心率的影响时，伦理风险评估变得不可或缺。风险不仅存在于身体层面，还可能涉及心理——参与者可能感到不适或尴尬。必须获得知情同意，且参与者应能随时退出。个人数据的保密性是另一项伦理要求。
The use of animals, even invertebrates like woodlice in a choice chamber experiment, warrants consideration of welfare. Projects must minimise stress, ensure appropriate housing and temperature, and return organisms to their habitat unless there is a valid reason not to. These ethical dimensions are not optional extras; they are embedded in the Cambridge syllabus under the umbrella of responsible science.
即使使用如潮虫等在选择室实验中的无脊椎动物，也需要考虑其福利。课题必须尽可能减少压力、保证适宜的栖息环境和温度，并在实验后将生物放归其栖息地（除非有充分理由不这么做）。这些伦理维度并非额外选项，而是深深植根于剑桥大纲中“负责的科学”这一概念之下。
12. Integrating Risk Assessment into Practical Planning | 将风险评估整合到实验规划中
Risk assessment should not be an afterthought tagged onto the end of a practical plan. It must be integrated from the moment a hypothesis is formed. When designing an investigation into the effect of antibiotic concentration on bacterial growth, the practitioner must simultaneously consider what concentration is safe to prepare, how to dispose of antibiotic-soaked discs, and whether the chosen bacterium is appropriate for an open bench.
风险评估不应是贴在实验计划末尾的事后想法，而必须从提出假设的那一刻起就融入其中。在设计关于抗生素浓度对细菌生长影响的探究时，实验者必须同时考虑配制多大浓度是安全的、如何处理浸泡过抗生素的纸片，以及所选的细菌是否适合在开放实验台上操作。
Cambridge examiners look for evidence of this integrated thinking in the planning section of practical papers. For example, a candidate might explicitly justify the choice of 1% hydrogen peroxide over 30% in a catalase experiment, not simply because the higher concentration would produce oxygen too quickly, but because 30% H₂O₂ is a severe oxidising hazard. Such reasoning demonstrates a mature understanding of risk in the context of biological methodology.
剑桥考官在实践试卷的计划部分会寻找这种整合性思维的证据。例如，考生可能会明确解释在过氧化氢酶实验中为何选择1%而非30%的过氧化氢，这不仅因为较高浓度产氧过快，更因为30%的H₂O₂是严重的氧化性危险源。这类论证展现了在生物学方法背景下对风险的成熟理解。
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