Blood, blood products & human tissue

Samples

Nature and source of samples

• A critical factor in the risk assessment is to consider the types of pathogens that may be present in the material given the distribution of specific pathogens within the body, and the likely incidence given the source (be it a donor, patient group, or general population).
• All human tissues will be contaminated with blood. Therefore they should be regarded as potentially infectious for BBVs. HIV has been detected in blood and blood products, in serum, plasma, breast milk, semen, vaginal and cervical secretions, urine, saliva, tears, peritoneal fluid, pleural fluid, pericardial fluid, synovial fluid, amniotic fluid and both cerebrospinal fluid (CSF) and brain tissue. There is also evidence that certain specialised cells lining the gut support the multiplication of HIV. Possible HIV contamination should therefore be taken into account when handling materials of these types in the laboratory.
• Other specimens such as faeces and urine are not regarded as posing HBV or HIV infection risk as long as they are not contaminated with blood. However, faeces in particular will contain various other pathogens. Sputum samples and specimens of lung tissues may contain Mycobacterium tuberculosis. Samples of neurological origin may contain disease-form prion proteins.
• Several factors should be taken in to account when assessing likely incidence. These include known medical history of a patient or donor, whether the samples are from individuals showing clinical symptoms of infectious disease, and the incidence of the various pathogens that are endemic in the local population. Any samples that have not been screened should be regarded as potentially infectious. The following provides some guideline examples:
  • The National Blood Service (NBS) will usually release out-of-date or surplus transfusion blood for non-clinical purposes. Since it has rigorous exclusion criteria for at risk donors and the blood is screened prior to release, blood obtained from the National Blood Transfusion Service may be regarded as one of the lowest risk sources (although this does not guarantee the sample is HIV negative because of the window between infection and seroconversion).
  • Samples from the general population in the UK would be regarded as low risk for BBVs whereas those from areas of the world where hepatitis and HIV are endemic would be regarded as higher risk.
  • If samples are from a specific group in the UK in which the incidence of BBVs was known to be significantly increased, such as intravenous drug users, then these too would be regarded as higher risk.
  • If samples are from individuals known to be, or because of clinical indications strongly suspected to be, infected with BBVs or other Hazard Group 3 pathogens, these would be regarded as high risk. In some stages of infection, the titre of virus in samples will be very high and this too should be taken in to account as part of the risk assessment.
  • Samples that might contain Hazard Group 4 pathogens are clearly the most hazardous but are not considered further here as there are no facilities in the University to handle these.
• It is a requirement under the COSHH Regulations to always consider whether a less hazardous substance, or form of the substance, can be used instead. If it can, then it should be used or justification be given as to why it is not being used. In many cases there will be good reasons for using samples from specific sources since these are the subject of the research. However if material is needed for control purposes or a specific source is not required, then the least hazardous should be used.

Using blood samples from healthy volunteers

• Researchers must not culture their own blood (or other cells) or that of their colleagues because of the risk of transformation of these cells by viral or other mechanisms followed by reintroduction into the body.
• Transformation of cells by SV40 or other means using donated blood from any individual working within a department is also not allowed.

Ethical considerations of other types of work are not considered here but should also be taken into account before starting work with blood or other human tissues.

It is also worth noting that blood is a particularly good medium for supporting the growth of a wide range of pathogens and contamination of the blood due to poor working practices may lead to potentially infective material (although these would be pathogens other than blood borne viruses).

Controls

Control measures

The following describes the control measures required for handling primary materials.

All work on unscreened samples must be undertaken at a minimum of Containment Level 2 with the additional precautions given in Appendix 1 (PDF , 22kb). These precautions supplement the basic Containment Level 2 requirements and are to provide extra protection against percutaneous inoculation, and contamination of the skin, mucous membranes and working surfaces. The rigour with which these control measures are applied should be proportionate to the risk. For higher risk samples, for example those from a source population where the incidence of BBVs is greater than 1% (but the samples are not known or strongly suspected to carry BBVs or other pathogens, see below for further guidance on these), particular effort should be directed at segregating the work from general laboratory activities and avoiding all possibility of percutaneous inoculation.

In general, work at Containment Level 2 does not need to be confined to a safety cabinet unless there is reason to believe the specimen contains other pathogens that do require such containment. There is no substantive evidence that supports aerosol transmission of HBV and HIV. However where handling or processing may generate aerosols, large droplets or splashes, appropriate containment control measures must be adopted.

The notable exception to the above is for work on sputum samples and specimens of lung tissues. These must always be handled in a microbiological safety cabinet because of the potential risk from Mycobacterium tuberculosis, even if there is no reason to believe the pathogen is present. Similar samples known to be from patients suffering from tuberculosis must be handled at Containment Level 3.

Where it is known or strongly suspected (clinical indications) that blood borne hepatitis viruses, HIV or HTLV are present then the samples must be regarded as high risk materials and handled at a minimum in a derogated Containment Level 3 facility as described in Appendix 2 (PDF , 16kb) Gas cylinder check procedures (PDF , 15kb)unless any viruses that may be present are to be concentrated or propagated, either intentionally or otherwise, in which case full Containment Level 3 must be applied.

If other Hazard Group 3 pathogens are known or strongly suspected to be present in the material then the samples must only be handled in a full Containment Level 3 facility. This is a requirement under the COSHH Regulations. Under certain circumstances the viruses listed in the previous paragraph are exempted from this requirement allowing derogation of certain control measures. Some Hazard Group 3 parasites and enteric pathogens are also exempted, the University Biological Safety Adviser can be contacted for further advice if samples are likely to contain these.

If there is any likelihood that materials might contain Hazard Group 4 pathogens these must not be brought in to the University. The University Biological Safety Adviser can be contacted for further advice.

Since this guidance covers an extremely wide range of research activities throughout the University some generalisations have been made. If a researcher believes the detailed risk assessment of their particular project justifies undertaking the work at a lower level of containment to that described here, the University Biological Safety Adviser should be consulted. Help and advice on risk assessment can be given on a case by case basis and researchers are urged to contact the University Biological Safety Adviser at an early stage.

Reception

Sample reception

All specimen reception should be undertaken in the laboratory by trained workers. Arrangements should be made to ensure that untrained workers do not inadvertently handle samples particularly if these are received in the postal system.

Disposal

Sample disposal

Human blood and other body fluids and tissues are regarded as hazardous clinical waste and must rendered safe before disposal.

All human material must ultimately be disposed of by incineration. Yellow bags or containers should be used and deposited in the clinical waste bins, located in the Biology Stores Compound Area. All sharps (e.g. needles) must be disposed of in clinical waste sharp bins. Infected human materials, or those samples suspected of being infected should be autoclaved first followed by incineration. It is important that where a central autoclave facility is used (e.g. in Biology) that:

• the local operators of the autoclaves are informed that the waste contains infected human material
• waste bags are labelled to indicate that infected human material is present

Accidents

Accidents

Immediately following any exposure the site of exposure e.g. wound or non-intact skin should be washed liberally with soap and water but without scrubbing. Antiseptics and skin washes should not be used - there is no evidence of their efficacy, and their effect on local defences is unknown. Free bleeding of puncture wounds should be encouraged gently but wounds should not be sucked. Exposed mucous membranes, including conjunctivae, should be irrigated copiously with water, before and after removing any contact lenses.

Particular care should be taken to ensure that others in the laboratory do not help with the clear up of accidental spillage (especially where there has been an accident that involves broken glass) if they are not aware of the potential risks and trained in safe working practices.

The source of any contamination (specimen, sample, material etc) should be clearly identified and retained for testing if necessary. Every effort should be made to ensure the confidentiality of persons potentially exposed to HIV as a result of an accident.

Accidents should be reported to and recorded by the person responsible for the work. The University Health and Safety Department and the Occupational Health Unit should be informed immediately in the event of any accident where exposure to a pathogen or infectious material may have occurred. A full accident record should be prepared and forwarded to the Health and Safety Department as soon as possible.

HIV

HIV

Under current guidelines samples can be tested for HIV only when informed consent has been given by the donor. The guidance provided above has been drawn up on the basis that testing is not feasible or practicable in many areas of research within the University. It is essential therefore that risk assessments take into account all available information and control measures are rigorously applied.

The HIV virus is not highly infectious nor particularly hardy and studies have shown that the occupational risk of exposure is low.  In the event of infection, HIV can now be effectively controlled with drug treatment like many other chronic conditions.