The Best Packaging for Biological Evidence

Biological evidence refers to any sample derived from a living organism that can serve as proof in an investigation. This includes bodily fluids and tissues that contain DNA or other biomarkers, such as blood, saliva, semen, urine, feces, hair, teeth, bone, and skin tissue. Such evidence is critical in forensic science because it can uniquely identify individuals or link suspects to crime scenes through DNA profiling. Given its importance, choosing the best packaging for biological evidence is essential to preserve its integrity from the crime scene to the courtroom.

Why Proper Packaging of Biological Evidence Matters

Handling and packaging biological evidence correctly is crucial to prevent contamination, degradation, and loss of evidentiary value. Biological samples are highly sensitive – exposure to heat, moisture, bacteria, or cross-contamination can destroy DNA or other forensic markers. For example, trapped moisture in an inappropriate container can promote mold growth, rendering a blood or tissue sample useless for DNA testing. Proper packaging also maintains the chain of custody, the documented trail of evidence handling. If an evidence bag is not sealed or labeled properly, its integrity can be challenged in court, and the evidence may even be deemed inadmissible. In short, the right packaging prevents contamination, preserves biological integrity, and protects the legal validity of the evidence.

Key reasons proper packaging is important:

• Prevent Contamination: Use sterile packaging and techniques to avoid introducing foreign DNA or microbes. Improper handling (e.g., using a wet plastic bag) can cause cross-contamination or microbial growth that compromises DNA analysis. Always wear gloves and change them between handling different items to avoid transferring biological material.

• Avoid Degradation: Biological evidence can degrade quickly due to environmental factors. Heat, humidity, and moisture are enemies – they can break down DNA and proteins. Packaging in breathable material (for damp evidence) or refrigeration for liquid samples helps preserve the sample.

• Maintain Chain of Custody: Each evidence item must be sealed and labeled in a way that any tampering is evident. Broken seals or missing labels undermine the chain of custody and can lead to evidence being thrown out. Proper packaging with tamper-evident seals and clear labels ensures a documented, unbroken custody trail from collection to analysis to courtroom.

Common Packaging Options (Paper, Plastic, and Specimen Bags)

Different types of containers are used to package biological evidence, each with advantages and limitations. The choice depends on the nature of the evidence (wet vs. dry, liquid vs. solid, etc.) and how it will be stored or transported. Below we compare paper bags, plastic bags, and specialized specimen evidence bags, and discuss when each is appropriate or inappropriate.

Paper Evidence Bags (Porous Bags or Envelopes)

Paper bags are a standard choice for most biological evidence, especially items that are moist or may carry cells that need to “breathe.” Paper is porous, allowing moisture to escape and the evidence to air-dry. This prevents the buildup of humidity that could cause mold or bacterial growth on samples. For example, bloody clothing, swabs of bodily fluids, or plant material are often packaged in paper bags or envelopes. Using paper helps preserve DNA in its original state by avoiding moisture-induced degradation.

Key features and uses of paper evidence packaging:

• Breathability: Paper’s porosity is ideal for wet or damp biological evidence like blood-stained fabrics or swabs. It allows evaporation of moisture, preventing mold that would occur in sealed plastic. (Items should still be air-dried as much as possible before final packaging.)

• Avoids Static and Smudging: Paper is non-static and won't cause latent prints or trace fibers to stick as easily as plastic might. This makes it good for trace evidence and DNA.

• Easy Labeling: The exterior of a paper bag is easy to write on with case details. Paper bags typically have large blank areas for recording evidence information and attaching chain-of-custody forms.

• Tamper-Evident Sealing: Paper bags can be sealed with evidence tape or staples over the fold. Once sealed with tamper-evident tape (signed and dated), any attempt to open will tear the paper or tape, providing visible proof of tampering.

• When Not to Use: Paper is not suitable for liquid samples or soaked items. Liquids would leak through, and a soaking-wet item can saturate and weaken the paper. Also, paper bags are less durable if subjected to rough handling or long-term storage in fluctuating environments (they can tear or degrade if not stored properly).

In summary, use paper bags for biological evidence that is dry or drying, such as swabs, dried stains, hair, or clothing – especially when residual moisture might be present. Paper packaging is not appropriate for free-standing liquids or very wet items, and it should be kept in a dry environment once evidence is inside.

Plastic Evidence Bags (Polyethylene Bags)

Plastic evidence bags (often made of polyethylene) are clear, waterproof, and durable, making them suitable for certain types of evidence – but caution is needed with biological materials. The main advantage of plastic bags is that they seal out external contaminants and retain all contents securely. They are tear-resistant and can protect evidence from outside liquids or dirt. The transparency allows investigators to see the contents without opening the bag, which is useful for quickly identifying evidence or presenting it in court.

However, standard plastic bags can trap moisture. For biological evidence that has not fully dried, this is a big problem: sealed plastic creates a humid microenvironment that encourages mold growth and DNA degradation. Thus, plastic bags are generally not used for wet biological samples unless those samples are properly dried or sealed in a separate leak-proof container first.

Appropriate uses and features of plastic evidence bags:

• Moisture-Proof & Durable: When sealed (zip-lock or adhesive), plastic bags are air- and water-tight, protecting evidence from any external moisture or leaks. They are excellent for dry, non-biological evidence (e.g. documents, electronics, shell casings) or biological samples that are already dry and stable. Plastic’s strength also makes it good for sharp or heavy items that might rip paper.

• Long-Term Storage: In long-term evidence storage, plastic offers better protection against humidity and oxygen for items like metals or electronics that could corrode. As long as biological stains are thoroughly dried and humidity is controlled, plastic can be used without harming DNA for long-term storage.

• Tamper-Evident Designs: Many forensic plastic bags come with tamper-evident features – e.g. a security adhesive strip that displays “VOID” if peeled, or built-in serial numbers and barcodes. Once sealed, any attempt to open the bag will leave visible damage or markings.

• When to Use: Use plastic bags for evidence that must stay dry or where leakage must be contained. For instance, “wet” evidence like a blood-soaked item should first be air-dried (or placed in a paper container temporarily to dry) before being repackaged in plastic. Plastic is recommended for solid or liquid samples that are already in secure primary containers. Examples: a tube of blood, a urine specimen container, or a moist swab sealed in a tube can be placed inside a secondary plastic evidence bag to prevent spills. Plastic bags are also favored for hazardous items (sharps, biohazard trash) because they are leak-proof and can be made puncture-resistant.

• When Not to Use: Do not use standard plastic bags for freshly collected, damp biological materials like wet blood swabs, fresh plant material, or bloody clothing that hasn’t dried. The lack of airflow will cause deterioration and microbial growth. Additionally, avoid using cheap household plastic baggies as evidence containers for critical samples – they may not have tamper-evident seals or sturdy material. If plastic must be used, choose purpose-made evidence bags with proper security features.

In summary, plastic evidence bags offer superior containment and durability for dry evidence or well-contained liquid samples, but they should never directly contain wet biological evidence that hasn’t been dried or secured, due to the risk of contamination and degradation.

Specimen Evidence Bags (Tamper-Evident Biohazard Bags)

Specimen evidence bags are specialized packaging designed for biological and medical samples, commonly used in laboratories, hospitals, and forensic labs. These are typically plastic pouches with built-in tamper-evident seals, biohazard markings, and labels to facilitate safe transport of biological evidence or diagnostic samples. A prime example is ADSURE’s Security Lab Specimen Bag, which embodies many ideal features for biological evidence packaging.

Features of a high-quality specimen evidence bag:

• Tamper-Evident Seal: Specimen bags usually have a one-time use adhesive seal. For instance, the ADSURE Security Lab Specimen Bag has a distinct tamper-evident tape closure – once sealed, any attempt to reopen will show obvious signs (the seal will tear or display a warning). This ensures evidence cannot be accessed without detection, safeguarding integrity.

• Biohazard Labeling: These bags are printed with the biohazard symbol and warnings, since they are meant for bodily fluids and potentially infectious materials. This compliance with OSHA/CDC guidelines alerts anyone handling the package to take precautions. (By regulation, any container used to store or transport blood or other potentially infectious material must be clearly labeled with the universal biohazard symbol or be colored red.)

• Leak-Proof & 95 kPa Rated: A hallmark of specimen transport bags is that they are leak-resistant and pressure-tested. ADSURE’s bags, for example, are made of high-strength film and engineered to withstand a 95 kPa pressure differential. This means they can endure air transport conditions (unpressurized cargo) without bursting, meeting the UN 3373 Category B requirements for shipping biological substances. The bags are waterproof and extremely tear-proof, providing a reliable secondary containment for sample.

• Chain-of-Custody Tracking: Many specimen evidence bags come with unique serial numbers, barcodes, and writable info sections. ADSURE’s bags are sequentially numbered with barcodes for traceability, so each sample can be logged and tracked. There is typically a dedicated area to record patient or case ID, contents, dates, and the signatures of those handling the evidence (or accompanying paperwork that fits into a second pouch).

• Dual Pouch and Accessories: A common design is a two-pocket bag – one compartment holds the actual specimen (e.g., a blood tube or swab container), and a separate pouch holds paperwork like evidence submission forms or chain-of-custody documents. This keeps paperwork dry and clean, even if the specimen leaks. Absorbent pads are often included inside to soak up any leakage and further protect the contents and handlers.

• Use Cases: Specimen evidence bags are ideal for liquid or wet biological samples (blood vials, urine containers, wet swabs) and any situation where evidence may be shipped or needs extra security. They are widely used for medical examiner samples, hospital rape kits, sexual assault forensic exam (SAFE) kits, and toxicology samples. In anti-doping and medical testing, these tamper-evident bags ensure samples remain sealed from the point of collection until analysis.

In practice, agencies often use a combination of packaging: for example, a swab from a crime scene might be air-dried and placed in a paper envelope at the scene, then that envelope is placed into a larger tamper-evident specimen bag for transport to the lab (providing both breathability and a sealed chain-of-custody package). High-quality evidence bags like ADSURE’s provide the best of both worlds – robust leak-proof protection and security features, with designs tailored to meet regulatory standards for biological substances.

Requirements of Ideal Packaging for Biological Evidence

Not all bags or containers are created equal. Ideal packaging for biological evidence should meet several key requirements to ensure the evidence remains intact, uncontaminated, and legally defensible. Here are the critical features to look for or incorporate when selecting packaging for biological samples:

• Tamper-Evident Sealing: The packaging must be designed so that once sealed, it cannot be opened without visible damage or leave evidence of entry. This can be achieved through tamper-evident tape, security seals, heat sealing, or built-in adhesive strips that show a “VOID” message when peeled.Tamper-evident packaging preserves chain-of-custody by preventing undetected access. If a bag is opened, the broken seal clearly alerts handlers that the integrity is compromised. Always seal evidence bags completely (no gaps or unsealed edges) and, if using tape, sign and date across the seal for additional security.

• Biohazard Labeling: Because biological evidence can pose health risks (bloodborne pathogens, etc.), any package containing such material should be clearly labeled with a biohazard symbol and legend. Official guidelines (like OSHA’s bloodborne pathogen standard) require that containers used for blood or OPIM (Other Potentially Infectious Materials) carry the universal biohazard label or an equivalent color-coding (fluorescent orange/red with the biohazard symbol). This warns anyone handling or transporting the evidence to use proper precautions. Many commercial evidence bags come pre-printed with the biohazard symbol for this reason. If your container is not pre-labeled, affix a BIOHAZARD sticker when packaging bodily fluids.

• Leak-Proof and Puncture-Resistant: Leak resistance is a must – the container should prevent any leakage of liquid evidence or preservative fluids. For liquid samples (like tubes of blood, urine, etc.), use screw-capped vials or tubes as the primary container, then place them in a secondary leak-proof bag. Packaging should also be able to contain the sample even if jostled or inverted. If there’s a risk of sharp objects (e.g., a bloody knife or a broken glass vial), the container must be puncture-resistant (consider a hard-plastic evidence tube or a strong plastic bag with a puncture-proof liner). Good practice for liquids is to include absorbent material inside the secondary bag to soak up spills. An ideal evidence bag for biological liquids (such as the Adsure specimen bag) is both watertight and pressure-tested to avoid leaks during transport.

• Chain-of-Custody Tracking: The packaging should facilitate easy and secure documentation of custody. This means having a dedicated area to record identifying information (case number, item number, description, date/time of collection, collector’s name/ID, etc.) and spaces for signatures when transfers occur. Many evidence bags have a built-in form or at least a large white write-on panel for this purpose. Additionally, unique identifiers on the packaging (like serial numbers or barcodes) greatly aid in tracking. For example, each Adsure tamper-evident bag comes with a unique serial number and barcode, allowing it to be logged and scanned into evidence management systems. This level of tracking helps prove that the specific bag (and its contents) presented in court is the same one collected at the scene. Always fill out all required fields on the bag or evidence label clearly and completely – missing info (like not labeling the date or who collected it) can call the evidence’s credibility into question.

• Compatibility with Cold Storage and Transport: Biological evidence often needs cooling to preserve DNA and prevent spoilage. Ideal packaging will withstand refrigeration or freezing without becoming brittle or leaking. Plastic evidence tubes and bags used for liquids should be rated for low temperatures. If evidence must be shipped or flown to a lab, the packaging should also meet transport regulations. For instance, 95 kPa pressure-resistance is required for air shipment of Category B biological substances – high-quality specimen transport bags meet this standard. The packaging system might involve triple-layer packaging for mailing: primary leak-proof container + secondary 95 kPa bag + rigid outer box with proper labels. In summary, choose packaging that remains secure in the conditions the evidence will be stored or transported (e.g., freezer, refrigerator, or long-distance shipment).

By ensuring these requirements are met, you significantly reduce the risk of evidence being contaminated, leaking, or questioned in court. Proper evidence bags (like ADSURE’s Security Lab Specimen Bags) exemplify these ideals, featuring tamper-evident seals, biohazard markings, leak-proof construction, unique serial numbers, and compliance with transport safety standards.Such packaging gives confidence that biological evidence will remain secure, identifiable, and intact until it reaches the forensic laboratory and beyond.

Best Practices for Sealing, Labeling, and Transporting Biological Evidence

In addition to choosing the right type of bag or container, how you seal, label, and handle the evidence package is equally important. Here are best practices that laboratory professionals, forensic investigators, and evidence custodians should follow:

• Wear Gloves and Prevent Contamination: Before touching any biological evidence or its packaging, put on a new pair of disposable gloves. Change gloves between different items to avoid cross-contamination. Consider using face masks and disposable tweezers or swabs as needed to further minimize shedding DNA or trace contaminants onto the evidence. Never cough, sneeze, or talk directly over open evidence. Packaging is your barrier — use it promptly.

• Use One Container per Item: Package each item of evidence separately to prevent cross-contamination and mixing of evidence. For example, if you have multiple bloody clothing items, each gets its own bag (and label). This also prevents evidence from different sources from contacting each other. Each container should be fully sealed before another item is packaged.

• Properly Insert and Fit the Evidence: Choose an appropriately sized bag or container so that you don’t have to force the evidence inside. Avoid folding or cramming items unnecessarily. If an item is too large for available bags, use clean butcher paper to wrap it and then place it in a paper bag or box. Ensure that wet evidence is air-dried (or at least wrapped in paper) before long-term packaging. Overstuffing a bag can cause it to rip or can squeeze out liquids, defeating the purpose of the packaging.

• Seal the Package Securely: Follow the designated sealing method of the evidence container. Different packaging will have different methods: some have peel-off adhesive strips, others require evidence tape. For paper bags, fold the top down several times and tape across the entire flap. For plastic bags with zip locks or adhesive, expel excess air if possible and ensure the closure is fully engaged. After sealing, no part of the opening should be exposed – the seal should be complete and tight. Tip: If using evidence tape, apply a strip that runs across the closure and onto the sides of the container; then write your initials or signature halfway on the tape and halfway on the packaging. This way, the tape itself becomes a tamper seal (it can’t be removed and reapplied cleanly). According to forensic guidelines, once a bag is sealed, it should not be reopened except by the lab; any reopening must be documented. Thus, double-check that you’ve included everything needed (like the evidence label or form) inside the bag before sealing it.

• Label Clearly and Comprehensively: Every evidence package must be labeled with key information to identify it. Typically, you should record: case number or identifier; item number; description of the evidence; date and time of collection; location where it was collected; collector’s name and badge/ID number; and any other relevant details (victim or suspect name, if applicable). Use a permanent marker or pen that won’t rub off. If the bag has a pre-printed evidence label section, fill out all fields. It’s often required to also label the package with the type of hazard (e.g., mark “Biohazard” if it isn’t already printed). Ensure writing is legible. In a lab setting, barcodes may be used – attach or scan them as protocol dictates. Never rely on memory or unmarked containers; an unlabeled sample might as well be garbage in forensic terms.

• Attach or Include Chain-of-Custody Forms: Most agencies require a chain-of-custody form that accompanies the evidence. Sometimes this is a tear-off receipt on the evidence bag itself, or a separate form that you place in a secondary pouch on the bag. Fill out the form immediately upon sealing the evidence: include the same details as on the bag label, plus your name and signature as the person who collected/sealed it, and the date/time. This form will be signed by each person who takes possession of the evidence bag thereafter. Some modern evidence bags include barcoded tracking systems or RFID chips – use these tools as provided to log transfers in evidence management software. The goal is to maintain an unbroken, documented record of who had the evidence and when.

• Controlled Storage Conditions: After packaging, store biological evidence in a controlled environment appropriate for its nature. Refrigerate or freeze wet biological samples (like liquid blood samples, rape kits, etc.) as required – typically, DNA evidence is best preserved cold to slow degradation. Dried stains on swabs or cloth can be stored at room temperature if the humidity is low and stable, but many labs still prefer refrigeration for any DNA evidence if space allows. The storage area should be secure (limited access) and ideally have environmental controls (cool, dry, and dark to prevent mold or UV damage). Always keep evidence out of direct sunlight and away from heat sources.

• Transportation Best Practices: When transporting biological evidence (from the scene to the lab, or between facilities), maintain proper conditions. Never leave biological evidence in a hot car or trunk for long periods, as heat can destroy DNA. If transport time is significant for liquid or fresh samples, use an insulated cooler with ice packs to keep them cool (but avoid direct contact of evidence with ice to prevent water exposure). For mailing or shipping evidence to another lab, follow legal requirements: use triple packaging for biological samples (primary sealed container, secondary leak-proof bag with absorbent, sturdy outer package with biohazard and “Exempt Human Specimen” or UN3373 Category B labels as appropriate). Ensure the package cannot be crushed in transit. Also, send via a reliable courier with tracking, and always document the transfer in the chain-of-custody record.

• Avoid Unapproved Modifications: Do not try to get creative with sealing methods that aren’t standard – for instance, using a household iron or hair straightener to heat-seal a bag is not recommended. While a hair straightener can technically melt-seal certain plastic bags closed, this is not a validated tamper-evident method for forensic evidence. It may overheat and damage the bag or evidence, and it won’t imprint the security markings that a proper evidence heat sealer does. Stick to official evidence tapes, heat sealers, or manufacturer-provided closures for sealing. If a bag is not sealing properly, discard it and use a new one rather than improvising in a way that might be questioned later.

By following these best practices, you ensure that biological evidence remains as pristine as possible and legally defensible. Meticulous sealing and labeling create a trustworthy presentation – an intact evidence bag with proper labels and unbroken seals gives judges and juries confidence that the sample inside is exactly what it purports to be. Moreover, careful packaging and handling protect the people working with the evidence from exposure to biohazards. In the end, a little extra diligence at the crime scene or lab in how evidence is packaged can make or break the success of forensic analysis and subsequent legal proceedings.

Conclusion

Proper packaging of biological evidence is not a mere procedural formality—it is a cornerstone of credible forensic practice. From preserving delicate DNA samples to ensuring an unbroken chain of custody, the right packaging materials and methods can directly influence whether justice is served. As forensic science advances and evidentiary standards grow more rigorous, law enforcement, laboratories, and healthcare professionals must stay vigilant about how samples are collected, sealed, labeled, and stored.

Whether it’s using breathable paper bags for drying bloodstains, leak-proof specimen bags for fluids, or tamper-evident packaging for courtroom admissibility, every choice in the packaging process carries weight. Solutions like ADSURE’s Security Lab Specimen Bags exemplify how purpose-built designs can meet legal, logistical, and biosafety requirements in one integrated form.

Ultimately, biological evidence tells a story. The role of proper packaging is to protect that story—unaltered, uncompromised, and ready to be heard.