|GATE - 1989/03 - Recycling (GTZ GATE Magazine, 1989)|
by Dietrich Hueber
Recently a hospital director in a Latin American city proudly announced that the infection rate among his patients had been reduced to 40 per cent since the hospital had started giving them penicillin routinely on admission! There is no doubt that such poor hygiene is in part due to the completely unacceptable refuse disposal methods used in such hospitals. And anyone could be exposed to the resulting high risk. If you are rushed to the nearest hospital after an accident you could be unlucky: the hospital you end up in may have an 80 per cent infection rate.
In most developing countries there are still no laws or regulations governing the treatment of hospital in part waste, which is in part infectious and therefore hazardous. The absence of clear directives and the lack of equipment, plus the fact that hospital personnel are unaware of the hazards of improper treatment of the waste, result in major risks for themselves, the patients and the visitors. Yet these risks can be avoided.
Today, the classic infectious diseases that were once dreaded no longer constitute a great risk. Hospitall infection, on the other hand, is a serious problem. It is "home-made", and is easily contracted by the patients, whose defensive reactions are weakened. This is why hospitals, which are densely populated places with a high proportion of carriers of dangerous pathogens, need highly efficient refuse disposal systems.
And what happens to the infectious waste once it has been removed from the wards? Of the few hospital incinerators which are in working order, most are in such poor condition that they are either not used at all, or only at night, to conceal the cloud of black smoke from the local inhabitants. Most hospitals, however, simply hand over all their waste unsorted to the domestic refuse collection services, without considering the consequences.
And the consequences can be serious: many developing countries have flourishing waste-recycling "industries" which provide a complete service, from refuse collection to final dumping. But while this may be desirable in principle, it is unacceptable when people who are ignorant of the health hazard involved - e.g. children - rummage in hospital waste with their bare hands looking for reusable objects. The risk of injury and infection as a result of handling used syringes or other disposable products and from recycling infected item is very high. Such recycling could also lead to outbreaks of epidemics endangering the entire population.
What is hospital waste?
As regards its type and composition, most hospital waste is similar to household waste and can be disposed of in the same way. In addition to this, however, hospitals generate certain special types of waste which should not be handled by domestic refuse collection services, because of the risk of infection, because they are hazardous in other ways, or for ethical reasons.
Such waste must be collected separately at the places where it is generated, and disposed of in specially approved plants, e.g., incinerators. Hence, types of hospital waste may be classified according to the disposal methods appropriate for them, as follows:
Type A: Waste which does not require any special treatment. This is the waste produced by the hospital administration, the cleaning service, the kitchens, stores and workshops. It can be disposed of in the same way as household waste.
Type B: Waste with which special precautions must be taken to prevent infection in the hospital.
This is usually taken to include all waste from inpatient and casualty wards and doctors' practices, e.g. used dressings, disposable linen and packaging materials.
It only constitutes a risk for patients with weakened defences while it is still inside the hospital. Once it has been removed from the wards it can be handled by the local domestic refuse collection service.
Type C: Waste which must be disposed of in a particular way to prevent infection.
This is waste from isolation wards for patients with infectious diseases; from dialysis wards and laboratories, in particular those for microbiological investigations, which contains pathogens of dangerous infectious diseases, e.g. tuberculosis, hepatitis infectious diarrhoeal diseases and which constitutes a real risk of infection when disposing of this waste. It includes needles and sharp objects coated with blood, or disposable items contaminated with stool.
Type D: Parts of human bodies: limbs, organs etc.
This waste originates in pathology, surgical, gynecological and obstetric departments. It has to be disposed of separately, not to prevent infection but for ethical reasons.
Type E: Other waste.
Hospitals provide a service, and hence have infrastructures which can also generate hazardous waste products, e. 9. chemical residues from laboratories, as well as inflammable, explosible, toxic or radioactive waste, which must be disposed of in accordance with statutory provisions.
Collecting and treating hospital waste
The fight against hospital infection demands the cooperation of all those employed in the hospital: doctors, technicians, nursing and cleaning staff. This is why one of the most urgent tasks is to convince, train and monitor the personnel responsible for refuse disposal. Unless they are convinced of the need, trained and monitored, all efforts to improve the situation will be doomed to failure.
Hospital waste should always be collected in disposable containers which satisfy the following requirements: they must be moisture-resistant and non-transparent; sellable in such a way as to prevent egress of micro-organisms; safe to transport; and colour-coded to distinguish them from household refuse bags. The waste must be collected in such containers at the point where it is generated, and removed from the wards daily without being sorted or transferred to other containers. The containers must be carefully sealed.
Generally, plastic bags are used for Type B and C waste, and plastic buckets for Type D waste. The material these disposable containers are made of must be appropriate for the next treatment stage. If the waste is subsequently incinerated, for example, combustible materials with a low level of toxicity must be used; if it is heat-disinfected the materials must be steam-permeable. This requirement also applies, incidentalIy, to all disposable items purchased by hospitals.
The waste must be transported to a central incineration plant outside the hospital in specially designed vehicles which do not compress it. The interior of the vehicle body must be easy to clean and it must be adequately ventilated.
Generally speaking, hospital waste should be burnt in appropriate incinerators: this is a recognized, proven method for disposing of all hospital waste. There are many different incineration systems available on the market today. Basically, an incineration plant should satisfy the following requirements:
· it should burn dry, wet and organic waste completely;
· glass, plastics and metals contained in the waste should
not impair the function of the plant in any way;
the combustion process should be fully automated, and exhaust gases should be within the statutory limits even if there are considerable differences in the calorific values of the waste;
it should have an automatically closing charging sluice to prevent operating personnel from coming into contact with the combustion chamber.
Plants which satisfy these requirements are now available in all sizes.
Alternatively, Type C waste can be disinfected and subsequently disposed of as household refuse, or, in special cases, removed to guarded sanitary landfills and immediately covered. Type D waste can be interred in an appropriate manner in cemeteries.
A variety of methods, chemical and physical, can be used for disinfection. To disinfect waste, however, only thermal systems in which the waste is steam-treated at temperatures above 105°C have so far proved successful. Disinfection in pressure-resistant installations involves approximately the same amount of work as incineration, but has the disadvantage that it is not possible to check visually whether the treatment has been a complete success. With incineration this is of course possible. For this reason incineration is to be preferred in countries which have no trained inspection personnel.
There are also devices on the market which shred waste and then disinfect it with liquid chemicals. These devices are only suitable for small quantities, mostly prone to breakdowns, and there is no guarantee that the disinfectant fluid will reach all the waste. They are not suitable for handling all the waste generated by a hospital.
Inadequate waste collection, handling and disposal promotes the;spread of infection in hospitals is and can thus undermine doctors' efforts to heal their patients. Moreover, it can cause infection outside the hospital. So proper dispose/ of hospital waste is in everyone's interest. To achieve this, clear guidelines must be issued; organizational measures are necessary; hospital personnel must be trained, convinced of the need for appropriate disposal method* and monitored, waste must be collected in disposable containers at the place where it is generated and transported without being transferred or compacted. Special waste must be burned in incinerators which are technologically up to date.
Une élimination déficiente des déchets et ordures favorise la propagation d'infections dans les hôpitaux. Par ailleurs, elle peut provoquer l'apparition de foyers d'infection a l'extérieur de l'hôpital. Une élimination parfaite des dé chets et ordures hospitaliers est donc dans l'intérêt de tous. Les élérnents essentiels sont d'une part l'établissement de directive sprécises ainsi que l'organisation, la formation, la sensibilisation et le contrôle du personnel hospitalier; d'autre part, il existe des éléments non négligeables tels que la collecte des déchets là où ils sont produits et ce, dans ces contenants jetables, et leur transport sans transvasement ni compression et leur incinération dans des installations techniquement appropriées.
La deficiente eliminación de basuras en un hospital facilita la ex tensión de las infecciones. Ademas puede provocar focos de infecciona fuera del recinto hospitalario. La eliminación correcta de los desechos hospitalarios es, por consiguiente, de sumo interés para todos. Los principales aspectos en este sentido son, por una parte, /a elaboración de normas de comportamiento claras y rigurosas, así como, por otra parte, la organización, preparación, capacitación y control del personal hospitalario. Otros aspectos se refieren a /a recogida de los desechos en el lugar en que se producen, en recipientes de un solo uso, y su transporte sin transbordos y su compactacion e incineración de los desechos especia/es en plantas que se ajusten a las modernas técnicas.