Incinerators and cement kilns that burn hazardous waste will never solve toxic waste problems. A clean production approach, which substitutes safe materials and processes to stop the generation of hazardous waste in the first place, is needed.
Reducing PVC use will reduce toxic output from medical waste
In medical waste incinerators PVC plastic is the dominant provider of chlorine - the element essential to dioxin formation. PVC enters medical facilities as packaging and in many disposable medical products, and becomes an estimated 9.4 percent of all infectious waste.
According to the majority of incineration studies, when all other factors are held constant, there is a direct correlation between input of PVC and output of dioxin. For this reason the Danish government policy is to avoid the presence of PVC in incinerators.
PVC also contains plastic softeners called pthalates, which are found to be carcinogenic in animals and have now been identified as a possible human carcinogen. Recent evidence also points to its hormone disrupting potential.
If all the PVC and chlorinated wastes were eliminated from the waste stream, there would be a significant reduction in the output of dioxin from incineration. But incineration would still be a poor solution due to high costs, loss of jobs in the recycling industry, lost profits from secondary resale, loss of energy and therefore requirement of further fossil fuel energy which generates the main greenhouse gas causing global warming and on-going contamination from heavy metal, hydrocarbon and other air emissions.
PVC products can be substituted with alternatives that are reusable and can be sterilised, and programmes can be implemented to prevent waste and increase reuse and recycling.
Currently there are often increased costs for PVC alternatives (often 20-30 percent more expensive). However these costs must be balanced against the cost of ongoing incineration fees and dioxin emissions.
Non-PVC hospital product alternatives
- Examination gloves: PE and/or PE copolymers are recommended. Latex is of higher quality and proven barrier to viruses.
- Overshoes: Clogs with leather tops in operating rooms; multiple-use rubber shoes, shoes made of cloth or overshoes made of PE for single use eg. visitors in intensive care rooms.
- Aprons: Cloth alternatives used in low contamination areas PE coated in operating rooms.
- Mattress covers: Alternative plastic and rubber use only where necessary washable microfibre, eg. "Kortex" or "Geritex", which is more comfortable to the patient.
- Wound plasters and dressings: Textile materials recommended.
- Bedpans: Stainless steel
- Syringes: PE and PP, sometimes ABS and natural rubber, Glass syringes for blood extraction
- Infusion equipment, bottles, and/or bags with suspension devices, tubings, tubing clamps, stop cocks: Non-PVC infusion equipment, eg glass for certain uses, PP, PE, PE/PA, EVA PCCE and PSU as well as multi use suspension devices for all common infusion receptacles.
- Tubing: EVA and EVA copolymers, PCCE or PE, in other fields of application, e.g. for respiration, silicon or rubber tubings.
- Stop cocks: PE, PC and PSU, often in combination of several plastics. Silicon adapters with connecting parts of PE and PP.
- Gastric probes: Silicon and PP catheters silicon and latex drainage bottles.
- Collecting bags: Glass, PE or PE/PP.
- Scalpels (disposable with PVC handles): Metal handles with interchangeable, sharpened blades.
- Breathing masks: Rubber, silicon or latex.
Alternative disposal of infectious waste
In general, 85 percent of the total medical waste stream in hospitals consists of the same mixture of discarded paper, plastic, glass, metal and food waste that is found in ordinary household waste. The remaining 15 percent is defined as infectious and these wastes must be sterilised before disposal.
A small percentage of this waste or 0.3 percent of the total medical waste stream, can only be incinerated, in part for cultural or aesthetic reasons, but also because it is difficult to sterilise in any other way. Thus there are dioxin-free means of disposing of 99.7 percent of the medical waste stream. Non hazardous waste can be recycled within a household waste recycling plan.
Alternative disinfection
For disposing of infectious waste there are several alternative dioxin-free methods that are cost comparative. Three of these are:
- Autoclaving and rotoclaving
- Microwave disinfection
- Superheated steam sterilisation
Autoclaving
An estimated 45 percent of infectious medical equipment from western hospitals is already reused through autoclaving. This is basically steam sterilisation, which encourages the reuse or recycling of medical equipment. Autoclaves are commercially available in varying sizes from desktop to industrial units.
The process involves heating bags of medical waste at between 120 and 1650C for 30 to 90 minutes in chambers into which pressurised steam is introduced. The steam penetration ensures destruction of bacteria and pathogenic micro-organisms. Waste is reduced by an estimated 75 percent of its volume and can either be landfilled directly or compacted further. The autoclaved infectious waste adds to the landfill burden, but the amount is usually less than 0.2 percent of the municipal solid waste stream. According to a survey of hospitals that have installed autoclaves, they are easier to operate than incinerators.
Cost benefits of autoclaving
A 1996 study by the Centre for the Biology of Natural Systems in New York examined the annual operating costs of hospital incinerators in the Great Lakes Region of North America and found that autoclaving was more profitable.
Autoclaving is the most profitable investment, unless there are no regulations at all on incineration emissions. Further assessment was made of the costs to hospitals of converting to autoclaves including paying off the debt on the original purchase of an incinerator. In this scenario conversion costs (6 million NZ dollars) are still cheaper than the annual operating cost of incineration with mandatory emission upgrading (7 million NZ dollars per year).
Microwave disinfection
Microwaving is economically competitive, versatile and studies in Europe have shown virtually no emissions, since the internal heating system is closed. Consequently there is no need for pollution control devices. Microwave disinfection relies on treating hospital waste with moist heat and conventional microwaves at temperatures of 940C. The equipment can be installed on or off site in stationary or mobile units. The remaining residues, which have been reduced by 80 percent in volume, can be landfilled.
Superheated steam sterilisation
This technology comprises a heated shredder and sterilisation unit. In the shredder, organic liquids are vaporised and solids reduced to gas by super-heated steam at temperatures between 500 and 700C. Medical equipment is melted into a sterile mass in under an hour. Remaining residues are cooled and dropped into a collection bin or ground in a heated shredder. The process has been shown to reduce medical waste by 50 to 80 percent of its original volume.