Incineration of waste and reported human health effects

HPS and the Scottish Environment Protection Agency (SEPA) have jointly published a report on incineration and reported human health effects. The report considers the evidence relating to the incineration of all forms of waste (hazardous, clinical and industrial, as well as municipal waste, which is the largest component of incinerated waste) and reported adverse health outcomes.

The topic is complex and has been studied over decades using various epidemiological and other methodologies. There has been a heavy reliance on ‘ecological’ type epidemiological studies, the proximity of home residence of individuals being often used as a proxy for exposure to airborne incinerator emissions, as a substitute for measuring actual exposure to airborne contamination. The reliance on such proxy measures puts limitations on the research findings, which therefore require careful interpretation. Much of the research was carried out in Europe and elsewhere during periods where airborne incinerator emission standards were less strict than is now the case in the UK.

The range of health outcomes covered in research literature is wide including: cancers, respiratory illness, birth outcomes (gender ratios, twin births), congenital malformations and infant mortality. The overall conclusions are:

• For waste incineration in general, the evidence for an association with (non-occupational) adverse human health effects is inconsistent and inconclusive.
• Some more recent work suggests that there may have been an association between some airborne emissions (particularly dioxins) from industrial, clinical and municipal waste incinerators in the past (before more stringent regulatory requirements were implemented) and some forms of cancer. However, this evidence is not completely conclusive and is inconsistent with other previous work.
• The magnitude of any health effects on residential populations living near incinerators in the past, if it occurred, is likely to have been very small.
• The majority of research work in this field is of historical relevance (when levels of incinerator emissions were likely to have been higher than now) but does not relate directly to the current risk of (non-occupational) adverse effects associated with incineration plants in operation now.
• Due to stricter legislative controls and improved technology, the levels of airborne emissions from individual incinerators should be lower now than in the past. Hence, any risk to the health of a local population living near an incinerator, associated with its emissions, should now be lower.
• It is possible that in the future the number of incinerators or the throughput of individual incinerators may rise, consequently the total mass of airborne emissions could increase. However, this has been addressed by the Scottish Government commitment to limit the total amount of waste destined for energy recovery via thermal treatment (incineration). In addition, planning controls should prevent new incinerators being sited within the locality of existing facilities.
• Any risk to human health associated with newer incinerators, operated within the current regulations, which are based on a precautionary approach, is likely to be minimal and very difficult to detect. The balance of evidence therefore suggests that a more precautionary approach to either the location of, or the operation of waste incinerators, is currently not recommended.

The report findings, that there is lack of a consistent or conclusive evidence of an association between (non-occupational) human health effects and waste incineration, is relatively reassuring. However, when new incinerators are planned, especially if there are particularly vulnerable populations nearby, or in localities where there are other sources of similar airborne emissions (including road traffic and other industrial sources), there will remain a need to take account of background ambient air quality in assessing the potential impact of a new facility.

HPS has also produced a Briefing Note based on the report. This Briefing Note is intended to assist health protection staff and others in answering questions relating to this topic.