接触时间与接触性质怎么判定

结论：这两个判定是整个评价的入口，判错后面全错

生物学评价需要考虑哪些终点，由两件事决定：产品与人体接触的性质，以及接触持续的时间。

这两个判定错了，后面所有工作的方向都会错——判轻了会漏项目，判重了会做不必要的试验。 前者是合规风险，后者是成本浪费。

实务中这两个判定常常被一笔带过，直接写个结论而不说依据。这样写，审查方无法判断结论是否成立，通常会被要求补充说明。

接触性质的分类

按接触对象，通常分为几类：

判定要按实际的、包括可预见的误用情形。 比如产品设计上只接触完好皮肤，但使用者常有皮肤破损（压疮风险人群），这种情形是否要按更严的类别考虑，需要论证。

同一产品的不同部件可能属于不同类别，应当分别判定。 比如轮椅的坐垫面套接触完好皮肤，而某些医疗用品的部分部件可能接触黏膜。

接触时间的分级

接触时间通常分为几档：短期、较长期、长期。各档的界限有明确定义，不同档次对应的评价终点不同。

判定时要注意：

累计而非单次。 多次使用的产品，接触时间要累加。

累加的范围。 通常按一定时间窗内的累计接触，具体规则要按适用的评价体系确定。

间隔的处理。 间断接触的累加方式需要说明。

保守原则。 处于两档边界附近时，取较严的一档更稳妥。

「累计」这一点是判定中最容易出错的地方。 单次使用半小时的产品，如果每天用、连续用几个月，累计时间可能落在更严的档次里。

判定依据怎么写

报告中的判定应当能让人复核，建议这样写：

描述实际使用方式。 谁用、怎么用、用多久、用多少次。

说明接触部位与接触方式。 直接还是间接、接触哪个组织。

给出累计时间的计算。 单次时长乘以频次，得出累计值。

说明判定结论及所落档次。 并说明为什么落在这一档。

说明保守性考虑。 如果取了更严的档次，说明理由。

这样写出来大约几百字，但它把整个评价的范围锚定住了，后面的项目选择就有了依据。

常见的判定误区

按说明书写的用法判定，忽略实际用法。 实际使用中的时长和频次可能超过说明书。

只按单次接触判定。 忽略累计。

未考虑可预见的误用。 使用者不按说明书使用是常见的，可预见的误用应当纳入考虑。

未区分不同部件。 整个产品按一个类别判定，忽略了部件差异。

忽略间接接触。 不直接接触人体但影响接触介质的材料。

忽略特殊人群。 使用者是儿童、老年人或有基础疾病时，判定可能需要调整。

第三项值得展开。 康复辅具的使用者常常长时间使用产品，远超设计预期。比如轮椅坐垫，设计假设每天使用几小时，实际可能是清醒时间全部使用。判定时应当按实际情况。

判定对试验范围的影响

判定结果直接决定需要考虑的终点范围：

接触性质越深入（从皮肤到黏膜到组织到血液），需要考虑的终点越多；接触时间越长，需要考虑的终点也越多。

所以判定的变化会显著改变工作量。 从短期接触改为长期接触，可能增加若干项试验；从皮肤接触改为黏膜接触也类似。

这也是为什么判定要有依据而不能随意 ——往轻判有合规风险，往重判有成本代价，都需要理由。

变更时的重新判定

以下情况应当重新判定：

预期用途扩展（比如从短期使用改为长期使用）；接触部位变化；使用人群变化；使用频次的说明发生变化；以及产品形态或结构改变导致接触方式改变。

「预期用途扩展」是最常见的触发因素。 产品在市场上被用于新的场景后，企业更新说明书扩展适应范围，此时生物学评价的判定基础已经改变，原评价可能不再覆盖。

建议把这个检查纳入说明书变更的审批流程——凡是修改预期用途或使用方式的，都要核对生物学评价是否仍然适用。

特殊使用场景的判定

康复辅具类产品有一些特殊的使用场景，判定时要专门考虑：

长期居家使用。 使用者可能每天十几小时接触同一件产品，持续数年。这种累计时间远超一般假设。

机构周转使用。 同一件产品被多位使用者先后使用，涉及清洁消毒对材料的影响，以及交叉使用的考虑。

使用者皮肤状况特殊。 压疮风险人群、皮肤脆弱的老年人，对刺激的耐受性低于一般人群。

出汗与体液接触。 长时间坐卧，接触界面常处于潮湿状态，物质迁移可能增加。

这几点说明：照搬一般消费品的判定假设，对这类产品可能不适用。 判定时应当按实际使用人群和使用方式来，必要时取更严的档次。

判定与产品资料的一致性

判定结论会体现在多份文件里，要保持一致：

说明书中的使用方式与使用时长；技术文件中的预期用途描述；生物学评价报告中的判定；风险管理文件中的相关描述；以及标签上的相关信息。

这几处如果不一致，审查时会被指出。 常见的情况是说明书写的使用时长与评价报告中的假设不符——一个写「每次不超过两小时」，另一个按「长期接触」评价，或者反过来。

建议在说明书定稿时做一次核对，确认使用方式的描述与评价的判定基础一致。

我们的做法

承接生物学相关委托时，我们会先和委托方一起把这两个判定做清楚，并把判定依据写下来。 依据写清楚之后，试验项目的选择就是顺理成章的事。

如果委托方给的判定与我们对产品实际使用方式的理解有出入，我们会提出来讨论。判定偏轻会导致试验做不全，将来在审查中被要求补做，时间成本更高。

如果你不确定产品的接触判定怎么做，可以把产品使用方式和使用人群发过来一起讨论，或者直接联系：132 4819 8029。能力范围见服务介绍，流程见检测流程，更多内容见知识库。

English version

Conclusion. Which endpoints a biological evaluation must consider is determined by two things: the nature of contact between product and body, and how long that contact lasts. Get these wrong and everything downstream points the wrong way. Judge too lightly and items are missed, which is a compliance risk; judge too heavily and unnecessary testing is performed, which wastes money. In practice both determinations are often passed over, with a conclusion stated and no basis given. Written that way, a reviewer cannot judge whether the conclusion holds and will generally ask for the reasoning.

Categories of contact. Contact with intact skin covers surface use on unbroken skin. Contact with mucosal membrane covers oral, nasal and gastrointestinal routes. Contact with breached surfaces covers wounds. External communicating contact covers blood and tissue paths. Contact with tissue or bone covers implants and surgical instruments. And blood contact covers direct or indirect exposure. Determination should reflect actual use including foreseeable misuse: where a product is designed for intact skin but users frequently have broken skin, as in populations at risk of pressure injury, whether a stricter category applies needs reasoning. Different parts of one product may fall into different categories and should be determined separately; a wheelchair cushion cover contacts intact skin, while parts of certain medical products may contact mucosa.

Tiers of duration. Contact duration is normally divided into short, prolonged and long-term tiers with defined boundaries, each carrying different endpoints. Several points matter. Duration accumulates rather than counting single exposures, so repeated use must be summed. The scope of accumulation follows the applicable evaluation system's rules for the relevant window. Intermittent contact requires an explained summation method. And a conservative principle applies near a boundary, where taking the stricter tier is safer. Accumulation is where determinations most often go wrong: a product used for half an hour at a time, daily, for months, may accumulate into a stricter tier.

Writing the basis. The determination in a report should be reviewable. Describe the actual manner of use: who uses it, how, for how long and how often. State the contacting site and mode, whether direct or indirect and which tissue. Give the accumulation calculation, single duration multiplied by frequency. State the conclusion and the tier reached, and why. And explain any conservatism where a stricter tier was taken. A few hundred words anchors the scope of the whole evaluation and gives the selection of test items a basis.

Common errors. Determining from the instructions rather than actual use, when real duration and frequency may exceed what the instructions describe. Determining from single exposure only, ignoring accumulation. Omitting foreseeable misuse, when departure from the instructions is common and foreseeable misuse should be considered. Failing to distinguish between parts, treating the whole product as one category. Overlooking indirect contact by materials that do not touch the body but affect what does. And overlooking special populations of children, the elderly or those with underlying conditions. The third deserves expanding: users of rehabilitation products often use them far longer than designers assumed. A wheelchair cushion designed on an assumption of a few hours daily may in fact be used for all waking hours, and the determination should reflect that.

Effect on test scope. The determination directly drives the endpoints to be considered: the deeper the contact, from skin through mucosa to tissue and blood, the more endpoints apply, and the longer the duration, likewise. A change of determination therefore changes the workload substantially, since moving from short-term to long-term contact, or from skin to mucosal contact, can add several test items. This is also why the determination needs a basis and cannot be arbitrary: judging light carries compliance risk and judging heavy carries cost, and both need reasons.

Re-determination on change. Re-determine where intended use is extended, for instance from short-term to long-term use; where the contacting site changes; where the user population changes; where stated frequency of use changes; and where product form or construction alters the mode of contact. Extension of intended use is the most frequent trigger: once a product is used in new settings in the market, manufacturers update the instructions to widen the indications, at which point the basis of the biological determination has changed and the original evaluation may no longer cover it. Build this check into the approval process for instruction changes, so that any modification to intended use or manner of use prompts a check on whether the biological evaluation still applies.

How we handle it. For biological work we settle both determinations with the client first and write down the basis. Once that is clear, the selection of test items follows naturally. Where the client's determination differs from our understanding of how the product is actually used, we raise it for discussion, because a determination that is too light leaves testing incomplete and supplementing it later, after review, costs more time.

Send us how the product is used and by whom and we will work through the determination. Phone or WeChat: +86 132 4819 8029.