色素与添加剂对生物学评价的影响

结论：用量最小的成分，往往是风险最集中的成分

一件塑料件里，基体树脂可能占九成以上，添加剂加起来只有百分之几。但生物学风险往往来自这百分之几。

原因是：基体树脂多数是分子量很大的聚合物，本身迁移性低；而添加剂是小分子，容易从材料中迁移出来进入接触介质。

所以生物学评价的注意力应当放在添加剂上，而实务中恰恰相反——企业常常只关注「用的是什么塑料」，对添加剂配方一无所知。

添加剂的主要种类

增塑剂的用量在柔性材料中可以很高，这类材料的评价要特别关注。

着色剂虽然用量小，但品种极多，而且颜色是市场部门常改的要素，所以它是变更频次较高的一项。

颜色变更的处理

这是实务中最常见的场景：产品要出新颜色，或者原色母断供换了牌号。

很多企业默认颜色变更不影响生物学安全，直接改了就生产。这个默认不成立，原因是：

不同颜色的色母，着色剂的化学成分完全不同；有的色母含有需要关注的金属化合物；色母的载体树脂和分散剂也可能不同；以及添加量可能不同。

合理的处理方式是： 把颜色变更纳入变更评审；获取新色母的成分信息；判断是否引入新的关注物质；必要时做化学表征对比或补充相关试验。

对于多色产品，建议按颜色分别评价或者选取代表性颜色，并说明选取的理由。直接用一种颜色的数据覆盖所有颜色，论证上是有缺口的。

抗菌处理的特殊考虑

抗菌功能近年常见于康复辅具，这类添加剂有其特殊性：

它的作用机理就是释放。 抗菌剂要起作用，就必须与微生物接触，多数依靠缓慢释放。而释放意味着人体也会接触到。

所以抗菌产品的生物学评价要专门考虑抗菌剂的暴露。 用量、释放速率、累计暴露量都要评估。

抗菌效果的持久性也要验证。 如果反复清洗后抗菌剂流失，宣称就不成立。

宣称要与证据对应。 宣称抑制什么、抑制程度如何、持续多久，都要有数据。

建议在产品定位阶段就想清楚是否真的需要抗菌功能。 增加这个功能会带来额外的评价负担和举证义务，而实际收益要看具体场景。

加工助剂的残留

除了配方中的添加剂，加工过程引入的物质也要考虑：

脱模剂；润滑油；清洗剂残留；模具表面处理物质；以及焊接、粘接过程中的物质。

这些物质不在材料配方里，容易被遗漏，但它们集中在产品表面，正是与人体接触的部位。

建议的做法是在材料清单之外，另做一份加工助剂清单，列出每道工序可能引入的物质，并说明后续工序（清洗）能去除多少。

供应商信息的获取

添加剂信息通常要向供应商索取，实务中的难点是供应商不愿提供配方。可行的做法：

要求提供符合性声明。 声明材料符合某些要求、不含某些物质。

签保密协议。 在保密前提下获取配方。

由供应商直接提供给评价方。 避免配方经过下游。

用化学表征代替。 拿不到配方时，直接测释放了什么。

约定变更告知义务。 这一条在合同中明确，比事后追查有效。

最后一条尤其重要。 供应商调整配方而下游不知情，是评价失效的常见原因，而这种情况从外观和常规检验上完全看不出来。

评价上的建议

材料清单要细到添加剂层级。 只写「聚丙烯」不够。

表面接触部件优先关注。 直接接触皮肤的部件风险更直接。

用化学表征验证配方信息。 两者互相印证。

变更管理覆盖颜色和供应商。 这两项是高频变更。

试样用最终状态。 经过全部加工、表面处理、灭菌。

从设计阶段就控制

添加剂带来的评价负担，很大一部分可以在设计阶段避免：

优先选择已有良好使用记录的材料体系。 医疗级牌号通常配方相对稳定、信息可获取。

避免不必要的功能性添加。 抗菌、香味、特殊外观效果，如果不是必需，增加的是评价负担。

减少颜色种类。 颜色越多，评价和变更管理的工作量越大。

统一供应商。 同一材料尽量用单一供应商，减少配方差异。

接触部件与非接触部件分开考虑。 接触部件用信息完整的材料，非接触部件可以放宽。

第五条能显著降低成本。 整件产品都用高等级材料没有必要，把要求集中在接触部件上更合理。

表征能发现什么

化学表征在添加剂问题上的作用很直接：

发现配方中未声明的物质。 供应商声明不含某物质，表征却检出，说明声明有问题。

比较不同颜色或批次的差异。 直接看释放物质谱。

发现加工引入的物质。 配方里没有但产品上有的。

跟踪供应商的配方变动。 定期表征对比可以发现悄悄的配方调整。

建议把定期表征纳入供应商管理，频次可以按材料的关键程度定。这比完全依赖供应商声明要可靠。

我们的做法

做生物学相关委托时，我们会要求提供材料清单，并且明确问到添加剂和色母的信息。 如果委托方拿不到，我们会建议先做化学表征——直接看释放了什么，比追查配方更快也更有说服力。

对于多颜色的产品，我们会建议按颜色做表征对比，确认不同颜色之间的释放物质是否有实质差异。差异不大的可以合并评价，差异明显的需要分别处理。

如果你在准备生物学评价，遇到添加剂信息不全的情况，可以把现有材料信息发过来一起讨论怎么处理，或者直接联系：132 4819 8029。能力范围见服务介绍，送检要求见送检要求，流程见检测流程。

English version

Conclusion. In a plastic component the base resin may account for more than ninety per cent of the mass while additives together amount to a few per cent. Biological risk, however, generally comes from those few per cent. The reason is that base resins are mostly high molecular weight polymers with low intrinsic mobility, while additives are small molecules that migrate readily out of the material into whatever it contacts. Attention in biological evaluation therefore belongs on the additives, whereas practice tends to run the other way, with manufacturers concerned about which plastic is used and knowing nothing about the additive package.

Principal additive types. Plasticisers increase flexibility and are notable for strong migration and high loading. Stabilisers prevent degradation during processing and use, and some contain metals. Colourants provide colour, with metal-containing types warranting attention. Antioxidants retard oxidation, and their degradation products must also be considered. Flame retardants improve fire performance, and some types attract concern. Lubricants and release agents aid processing and leave surface residues. And antimicrobials inhibit microorganisms, raising questions of release and durability. Plasticiser loading can be high in flexible materials, so their evaluation deserves particular attention. Colourants, though used in small quantities, come in a very wide variety, and colour is an element marketing departments change often, making it a high-frequency change item.

Handling colour changes. This is the most common scenario in practice: a new colour is introduced, or the original masterbatch is discontinued and replaced. Many manufacturers assume a colour change does not affect biological safety and simply produce the new colour. The assumption does not hold, because masterbatches of different colours contain chemically quite different colourants, some contain metal compounds warranting attention, carrier resins and dispersants may differ, and loading levels may differ. The proper handling is to bring colour changes into change review, obtain composition information for the new masterbatch, judge whether new substances of concern are introduced, and where needed perform comparative chemical characterisation or supplementary testing. For multi-colour products, evaluate by colour or select representative colours with the selection justified; using data from one colour to cover all leaves a gap in the argument.

Antimicrobial treatment. Antimicrobial functionality has become common in rehabilitation products, and such additives are a special case, because their mechanism is release: to act, the agent must contact microorganisms, and most rely on slow release, which means the body is exposed too. Biological evaluation of antimicrobial products must therefore specifically address exposure to the agent, assessing loading, release rate and cumulative exposure. Durability of the effect must also be verified, since a claim fails if the agent is washed out. And claims must match evidence, with data supporting what is inhibited, to what degree and for how long. Decide during product positioning whether antimicrobial function is genuinely needed: adding it brings additional evaluation burden and evidential obligations, and the benefit depends on the specific application.

Processing residues. Beyond formulation additives, substances introduced during processing must be considered: release agents, lubricating oils, cleaning agent residues, substances from mould surface treatments, and substances from welding and bonding. These are not in the material formulation and are easily overlooked, yet they concentrate at the product surface, which is precisely where contact with the body occurs. Alongside the material list, compile a processing aid list setting out what each operation may introduce and how much subsequent operations such as cleaning remove.

Obtaining supplier information. Additive information must generally be requested from suppliers, and the practical difficulty is reluctance to disclose formulations. Workable approaches are requesting a declaration of conformity stating that the material meets certain requirements and is free of certain substances; signing a confidentiality agreement to obtain the formulation; having the supplier provide it directly to the evaluator, bypassing the customer; substituting chemical characterisation, measuring what is released where the formulation cannot be obtained; and contracting for notification of change. The last matters particularly: a supplier adjusting a formulation without telling the customer is a common cause of evaluations becoming invalid, and the change is entirely invisible in appearance and routine inspection.

Recommendations. Take the material list down to additive level, since polypropylene alone is not enough. Prioritise surface-contacting components, whose risk is most direct. Use chemical characterisation to corroborate formulation information. Ensure change management covers colour and supplier, both high-frequency changes. And use final-condition specimens that have been through all processing, surface treatment and sterilisation.

How we handle it. For biological work we ask for the material list and specifically about additives and masterbatch. Where the client cannot obtain them we suggest chemical characterisation first, since measuring what is actually released is faster and more persuasive than tracing formulations. For multi-colour products we suggest comparative characterisation by colour to establish whether released substances differ substantively; where they do not, colours can be evaluated together, and where they do, separately.

Send us what material information you have and we will work out how to proceed. Phone or WeChat: +86 132 4819 8029.