Half the world’s population could be at risk from exposure to mounting volumes of improperly disposed medical waste, according to a review published this month in Tropical Medicine and International Health.

 

“The documented growth in and poor disposal of health care waste appears to represent a real threat to the health of at least 40… low and middle income nations,” write Michael Harhay, from the University of Pennsylvania, USA, and colleagues.

 

Some experts are wary of pinning down the number of people at risk because data are limited. But they admit the problem is growing.

 

Hospitals and clinics around the world can generate up to 6 kg of hazardous waste per person per year. This can be anything from soiled dressings to diagnostic samples, body parts, and used needles.

 

In many wealthy countries, hazardous medical waste is separated from rubbish and is disposed of using incinerators with emission-cleaning equipment. But low-income countries rarely have the tools to dispose of dangerous waste properly, leaving a reservoir of dangerous pathogens lurking in the environment.

 

In October 2008 in Afghanistan, the by-products of a polio vaccination campaign that served 1.6 million people were thrown into a Kabul rubbish tip, causing “infectious injury” to people scavenging for re-usable items in the area. An investigation revealed that the country has no regulations to control the disposal of medical waste. At least 60 hospitals in the city have no access to incinerators and other tools that can dispose of it.

 

To better understand how many people could be affected by poor waste management practices in low- and middle-income countries, Harhay and colleagues reviewed the available literature. Looking at 82 reports from 37 countries, they found that medical workers are under-trained in waste disposal, not provided with sufficient information, and have no access to systems that segregate medical rubbish. There is also widespread confusion over who is responsible locally for the sorting and disposal of medical waste, a task that is under-funded, they add.

 

A black market of used medical products also exists in some countries. Earlier this year, 240 people developed hepatitis B in the Indian state of Gujarat after receiving injections from re-used syringes that had been sold on for profit. Research suggests that up to six million jabs are given annually using second-hand equipment in Indian health facilities.

 

Six of the world’s most populated countries — China, India, Brazil, Pakistan, Bangladesh and Nigeria — have problems with the management of healthcare waste, according to the report. The authors say this puts around 50% of the global population at risk from the environmental, occupational, and public health consequences of improper disposal.

 

“In almost all settings, it was reported that the volume of waste was increasing beyond management capacity,” they write. As more low- and middle-income countries treat increasing numbers of people with chronic conditions, and as patients live longer, the problem will only grow further, they add.

 

Ashok Shekdar, from the Nagpur Institute of Technology in India, agrees the problem is growing, but says it is difficult to make predictions about the number of people affected as reliable data are scarce. He does not believe that half the world’s population is at risk.

 

In countries with a growing economy, such as India, there is no shortage of funds for healthcare waste management, explains Shekdar. But if these processes are to work effectively, he says, they must be part of a wider framework for general garbage collection run by local authorities — services that are sometimes neglected in poorer regions.

 

In countries with limited resources, the WHO recommends that medical waste is incinerated. But they recognise this is not ideal, explains Harhay, as the mix of needles, plastics and other materials can release harmful chemicals into the atmosphere and leave piles of ash made up of highly condensed pollutants. These toxic by-products can get into homes and water supplies. Exposure to them can cause health problems such as asthma, chronic obstructive pulmonary disease, and mercury poisoning, adds Harhay.

 

In the review, his team found that developing countries reported their incinerators to be broken down or antiquated, prompting medical workers to throw healthcare waste into municipal dumps. In some cases, waste was openly burned and buried on site, they explain.

 

Around 15–20% of healthcare waste is made up of items harbouring infectious agents, explains Shekdar. Incineration is not the only option to make it safe, he says. It may be more appropriate to disinfect this portion of the waste and then dispose of it together with other rubbish.

 

Harhay believes that better sorting and recycling of re-useable bits of waste can help to reduce the overall volume of medical rubbish. “But this is not often possible without overall waste management systems, such as private companies that will handle disposal,” he says.

 

Just burning the rubbish in an incinerator is not the answer, explains Harhay . A better solution lies in changing the way health care is delivered, so that less dangerous waste is generated in the first place.

 

“What we really need is new and more efficient tools, such as needleless modes of drug delivery, forms of vaccines that are inhalable… diagnostics that can use salvia rather than the need to draw blood,” says Harhay. “Innovation across the board is the only true answer.”