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Scope and limitations of the current review

Background

This review follows on from an earlier 2011 publication: which examined the potential impact on human health from chemicals emitted or released from active municipal landfill sites. The work on landfill sites and other forms of waste management published by the Department for Environment, Food and Rural Affairs (Defra) in 2004, incorporated a review of the assessment by the Royal Society. The Health Protection Agency (HPA) then carried out a review of more recent research into the suggested links between emissions from landfill sites and effects on health. The review encompassed the results of a number of epidemiological studies, detailed monitoring results from a major project funded by the Environment Agency (EA), and advice sought from the Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT). The HPA concluded that 鈥渓iving close to a well-managed landfill site does not pose a significant risk to human health鈥�.

This review鈥檚 scope and content

In this follow-on review we have looked at evidence of potential health effects in populations potentially exposed to chemicals emitted from landfill sites published since the evidence was gathered for the . Studies from all Organisation for Economic Co-operation and Development (OECD) countries have been considered, which cover a wide range of landfill waste disposal activities and site management procedures, some of which may not be fully relevant to the UK, as regulatory practices may be different.听

The previous report only considered active (operational) sites. For this review we have considered a number of different active and non-operational sites, listed below.

Active, operational landfills

Active sites are permitted under the Environmental Permitting Regime by the EA and are accepting waste.听

Closed landfills

These are sites that are not active (closed sites, not accepting waste), but have not surrendered their permit so are still regulated by the EA. Although no waste is accepted, the site will be undergoing aftercare and monitoring as part of the permit surrender process.

Surrendered landfills

These were formerly permitted sites where the environmental regulator (the EA) has accepted that the closed landfill no longer poses a significant risk to the public or the environment and as a consequence has accepted that the permit is formally surrendered. Due to the risk assessment carried out, these surrendered sites do not concern us further in this assessment.

Historic landfills

These are legacy sites, many of which pre-date environmental regulation.听These sites no longer have a permit or licence (or never had a licence) and are the responsibility of the landowner or the local authority, and in some cases may be managed by the local authority where emissions are known to be ongoing.

The EA holds data on historic and current landfill sites.听The historic landfill data set includes sites that existed before landfills were regulated, and therefore data may be incomplete as this pre-regulation data was taken from a national survey in the early 1990s. It also includes sites that were licensed where that licence is no longer in force, in accordance with the legislation at the time.

In England, there are approximately 19,801 landfill sites, which have been identified by Defra (former DoE) and held by the EA, listed as that existed before permitting, and permitted sites that have been surrendered or revoked. The number of landfill sites actively operating is much smaller.听 (downloaded in September 2022) indicates 1,602 permitted landfills, of which 535 are operational in England.

With regard to non-hazardous landfills, there are approximately 267 that are permitted and not accepting waste (closed sites designated by the EA as A4: household, commercial and industrial waste landfill) and 255 that are actively taking non-hazardous waste (designated by the EA as L02 and L04).听Of these, approximately 24 can accept hazardous waste (L01 and L06) and the other 511 active sites are non-hazardous and inert waste streams.听

Active sites are today strictly regulated and monitored in how they are designed and constructed, what type of waste they accept, how waste is transported, and how waste is managed on site, so that any risks to the environment including public health from their operation are minimised or non-existent.听This is encompassed within EA guidance: landfill operators: environmental permits.听

Therefore, there are 20,668 landfill sites which are considered to be closed (and probably not designed to modern landfill standards) or have no permit (referred to as 鈥檋istoric sites鈥�), but which may still be actively emitting chemicals to air or water. These historic and closed sites may still contain decomposing buried waste decades after they have ceased accepting waste, and gasses and vapours may continue to be emitted to atmosphere.

Dissolved chemicals may be mobilised from the landfill site in leachate and pollute nearby water resources.听The land where they are sited may have been restored for a variety of uses such as housing, industry, amenity, public open space, grassland, arable and so on and this proximity, particularly for those people living on the surface of these sites, presents a possibility of exposure to emitted chemicals. Poor record keeping about what wastes were accepted at these historic sites, their precise location and a lack of documentary evidence on how the land was returned to beneficial use, adds a further difficulty in assessing the public health impact of these sites.

In the , the evidence available at the time focussed mainly on specific long-term health impacts such as reproductive outcomes and cancer and concerned mainly populations living in the vicinity of active landfill sites. In more recent years, additional concerns related to respiratory health (such as asthma attacks) and the impact of odours on mental health and wellbeing have been raised in connection with living near to or on landfill sites and these aspects are now considered in this review.听

This review considers the major landfill pollutant routes (leachate, gas and odour), but specific guidance is available in the landfill sector technical guidance.

This includes:

• landfill engineering, including liners and stability
• landfill gas management, monitoring and use of flares
• landfill monitoring of leachate, groundwater and surface water, and conducting a hydrogeological risk assessment

Information is available on developing a new non-hazardous landfill site and an environmental setting and installation design (ESID) report.

Waste disposal and landfills: legislation and guidance

Whereas in the past, landfills may have been based on the need to level holes in the ground (such as natural valleys and quarries) and thus filled with waste so that sites could be put back into use (farming, housing, and so on), modern landfills employ a number of technologies to ensure that the emissions to air or water are properly managed. Gases generated by waste within the site can be pumped out from the landfill and can either be burnt off or can be collected and used to generate electricity. Engineered membranes and liners are used to prevent leachate from impacting on groundwater; leachate and surface water run-off is collected and must be treated before disposal or it has to meet limits for discharge direct to water.

While environmental permitting regulations for landfill are strict, and the industry is slowly being phased out with a preference for destruction or recycling of waste materials, the EA estimated there was still 388,366,504m³ landfill capacity in England for use at the end of 2020.

Current UK legislation covering waste disposal by landfilling stems from the , which was adopted into UK law in 2002 and has been updated in law to comply after Brexit 鈥� . The Landfill Directive is now primarily enforced in England via the and its amendments (which replaced its earlier iterations).

Prior to these developments, landfill sites were regulated under Waste Disposal Licences (WDL) or the subsequent Waste Management Licences (WML); many of the WML conditions are still in force under newer permits. Of the 1,602 permitted landfills, it is very likely that those not in operation (1,067 sites) have permits based on the conditions given under the earlier WML Regulations 1994. These sites are operated under a working plan agreed with the relevant regulator at the time and cover environmental control systems, monitoring and operational requirements. A few of this number may be previously closed sites where the licence was not returned to the regulator by the due date of May 1994.

In addition, the majority of sites are deemed historic and have no licence. These are sites which were either closed prior to the introduction of the or those sites which closed after that date and where the WDL licence was returned to the regulator by May 1994 or where the EA accepted formal surrender. The ownership or control of the vast majority of these sites (approximately 70%) is unknown.听Any contamination arising has to be dealt with by Part 2A of the (England, Wales, Scotland) or .

Active sites

Many of the current active sites will have sought planning permission, prior to preparing detailed assessments for their permit.听The Directive and national legislative developments have significantly changed the way in which waste has been disposed of to landfill in the past 25 years.听Three classes of landfill site were identified in the :

• landfills for inert waste only
• landfills for non-hazardous waste
• landfills for hazardous waste

This report considers municipal (non-hazardous waste) only.听There are now strict restrictions on the types of waste that each class of landfill can accept. Various materials are now banned from landfill including all liquid wastes, corrosive, explosive or flammable waste, hospital and clinical infectious waste, whole used tyres (since 2003) and shredded used tyres (from 2006). Waste going to landfill is also required to be pre-treated (including sorting) to encourage recovery and recycling or reduce its pollution potential. In addition, there are now requirements to ensure that waste entering landfill meets the relevant waste acceptance criteria for the class of landfill. The aim of these criteria is to ensure waste goes to the correct class of landfill. These restrictions serve to reduce the potential of modern landfills to contaminate the local environment. There are also strict monitoring requirements and limitations for substances which might be released to air, soil or water. This data may be collected by the landfill operator or the EA.

Although not a direct chemical effect, odour annoyance from landfills is also regulated via the environmental permit, but not in the same detail as the potential release of gasses with the potential to be inhaled.

Modern active landfills across the EU therefore present much reduced potential to release contaminants into the wider environment than those in operation decades ago. These older sites were mainly the types of sites considered in the . Even the more recent health investigations identified in this review need to be considered in the context of standards operating at the time of the study along with the age and status of the landfill in question; the relevance of these findings to people living close to currently operating landfill sites must be viewed in that respect.

Surrendered sites

To accept an application to surrender, an environmental permit for a site involving the permanent deposit of waste, the EA must be satisfied that:

• the site has ceased accepting waste
• an appropriate period of aftercare has passed to allow the waste to stabilise and to gather evidence to demonstrate that the pollution control measures are no longer necessary
• appropriate controls are in place to ensure that the waste, if left undisturbed, will not cause pollution of the environment

Therefore, a surrendered site has been assessed for landfill gas emissions, internal leachate levels, external groundwater, infiltration of water through the cap and potentially sides and base, and surface runoff.听The various components of the landfill lining system which may deteriorate over time are considered, along with settlement completion criteria and slope stability. Surrender is not accepted until it can be demonstrated that future degradation of the lining system will not result in an unacceptable discharge and the EA supports this process through guidance.

Closed sites

Former, now closed, landfills, may however present a different type of concern if their closure and aftercare has not been carried out to current best environmental practice. The management and care of closed landfill sites is dependent on whether the operator has the necessary resources and funding available.

Many landfills were previously operated and owned by local authorities under the older legislation ( and ).听Operations were then transferred to local authority waste disposal companies (LAWDaC) and generally sold on to private waste management companies in the late 1990s or early 2000s. Some of the licences were transferred back to the local authority once disposal was complete. Thus, many closed landfill sites are still managed by local authorities.听Even after sites are closed, bacteria in the buried waste will cause it to decompose, producing 鈥檒andfill gas鈥� containing mainly methane (CH₄) and carbon dioxide (CO₂), and trace amounts of other volatile substances. This process can last for several decades.

After closure, these sites were generally 鈥榗apped鈥�, that is sealed with layers of clay and topsoil and were planted to restore a natural appearance. Ongoing gas release at closed sites is managed by actively pumping聽out and burning gas by a process called 鈥榝laring鈥� in specially built flaring units聽which break down the methane into carbon dioxide; where there is insufficient gas productions to sustain active extraction, sites are regularly monitored.听There are often leachate treatment systems to manage water from inside the site and prevent dissolved methane entering sewers. Such sites may contribute to greenhouse gas emissions and are often managed as greenspace.

Historic sites

Under the , landfill licences could be 鈥榟anded back鈥� by licence holders to the 鈥榙isposal authority鈥� (which was part of the local authority鈥檚 remit at that time) which enabled many operators to walk away from a site without any closing criteria.听In addition, dilution and dispersion were used as a landfill technique (no lining was installed, and any leachate would be attenuated in the underlying soil and/or diluted by groundwater), and co-disposal could occur (normally hazardous and non-hazardous waste).听Liquid could also be disposed of on many such sites. Prior to the Control of Pollution Act 1974, there was no usage or aftercare plan. There is an absence of adequate records for such sites and so it is not known whether these sites may still be releasing gas or leachate into the environment or what types of waste were disposed there.听Some sites which took hazardous chemical waste may be tagged as such, but generally, proximity to industry is the only clue. These issues may only come to light when former sites are either investigated by the local authority under or when a site is proposed for development and a planning application is made. Remedial measures may then be implemented to control any risks to health or the environment.

In addition to natural restoration of closed sites and also if the requirements of the are fulfilled (that is, deemed not to present a significant possibility of significant harm to human health or the environment), the land can be used for a variety of suitable purposes, such as public amenity, educational premises, leisure centres, public open space, industrial use or residential housing.

Future trends 聽

Defra published its Waste Management Plan for England in January 2021.听This was written as part of the 25 Year Environment Plan and fulfils the requirements of the for the waste management plan to be reviewed every 6 years. This also includes the changes to these requirements made by the .听

The Resources and waste strategy for England sets out how England will preserve resources by minimising waste, promoting resource efficiency, and moving towards a circular economy, identifying 5 strategic ambitions:

• working towards all plastic packaging placed on the market being recyclable, reusable, or compostable by 2025
• working towards eliminating food waste to landfill by 2030
• eliminating avoidable plastic waste over the lifetime of the 25 Year Environment Plan
• doubling resource productivity by 2050
• eliminating avoidable waste of all kinds by 2050

The strategy limits municipal waste going to landfill by 2035, to only 10% or less of the total amount of municipal waste generated (by weight).听Defra, however, does recognise there is an ongoing role for landfill in managing waste, particularly for inert waste that cannot be prevented, recovered or recycled, but that its use should be minimised as much as possible.

Such materials are likely to include:

• some hazardous wastes 鈥� such as asbestos
• certain process residues, such as pre-treated industrial wastes from which no further resources can be recovered
• waste for which the alternatives to landfill are not justified on cost or environmental and resource efficiency grounds

This all leads to a change in landfill composition over time, with low gas production, but potentially increased toxicology or potentially corrosiveness of waste products, affecting liner integrity.

The (amending Directive 1999/31/EC on the landfill of waste) of the European Parliament and of The Council, of 30 May 2018 amended the:

• Waste Framework Directive (2008/98/EC)
• Landfilling Directive (1999/31/EC)
• Packaging Waste Directive (94/62/EC)
• Directives on End-of-Life Vehicles (2000/53/EC), on Batteries and Accumulators and Waste Batteries and Accumulators (2006/66/EC), and on Waste Electrical and Electronic Equipment (2012/19/EU)

This directive was transposed into UK law and thus the EU is also limiting landfill in its member states.听Work carried out for the European Commission (European Innovation Partnership (EIP) on raw materials commitments (RMC)) identified that , of which 90% are non-sanitary landfills, predating the Landfill Directive (1999). Therefore, work has been carried out by聽the European Enhanced Landfill Mining Consortium (EURELCO) who has identified that significant quantities of waste electrical and electronic equipment (WEEE) were disposed in landfill, especially prior to the implementation of the聽.

Sites are also considered to contain substantial amounts of material which could have otherwise been recycled such as aluminium cans, plastic bottles and paper. Therefore, currently lined and closed landfills could be reopened to mine the waste.听Exposure routes would be similar to active sites, although dust composition would be unknown.

Landfill sites and exposure

Exposure routes

There are several pathways by which substances may be released or emitted from both active and closed or historic landfill sites and thereby provide an exposure route that may have consequences for public health.

Particulate matter, dust, odours, vapours, and gasses can be liberated from active sites during waste transportation, active tipping, site management activities and from the decomposition of waste materials. Depending on the prevailing atmospheric conditions, such as wind direction, wind intensity and rainfall, airborne emissions can be transported to nearby residents. In addition to the concentrations being released from the site, an individual鈥檚 proximity to the site and the length of time they spend close to a site are also important factors in determining the level of inhalation exposure, and thus the potential risk to their health.

Dissolved substances in leachate may also provide a pathway for exposure. If groundwater is contaminated by leachate, then there are several routes by which exposure may arise, particularly if water is accessed through wells as a private supply. Potential exposures may arise through consumption of contaminated drinking water, its use for cooking, or through home-grown produce if contaminated water is used for crop irrigation. Also, any volatile contaminants in leachate reaching groundwater could also release vapours and lead to an exposure by inhalation at locations distant from the landfill site.听Where groundwater is not used or is first treated for a public supply source, risk is minimised; however, surface water contaminated by leachate can pose a recreational risk.

Active sites

Potential exposure routes:

• the waste materials as they are brought onto site, normally in heavy goods vehicles
• emissions from this transport and any heavy plant used on site
• waste blown by the wind as it is tipped or deposited at the landfill site
• dust generated from the surface of the landfill and when waste is tipped or unloaded
• the waste materials which have previously been deposited in the landfill site
• any gas or vapour generated as the waste breaks down, which is not collected and treated
• odours from waste as it is unloaded or as it breaks down
• any plant used to burn landfill gas, including gas flares or engines
• any leachate produced as the waste breaks down entering surface or groundwater
• the discharges from any processes used to treat the leachate

Closed and historic sites

Potential exposure routes:

• dust generated from the surface of the landfill if not capped
• any gas or vapour generated as the waste breaks down, which is not collected and treated
• odours from waste as it breaks down
• any plant used to burn landfill gas, including gas flares or engines
• any leachate produced as the waste breaks down entering ground or surface water
• the discharges from any processes used to treat the leachate

Exposure pathways to the population

Based on the possible exposure routes above, the most common route of exposure is via inhalation.听While dust and leachate may pose a dermal risk if they come into contact with skin, the most important pathway is via respiration.听Of this, vapours, gasses, and respirable particulates (<PM10) will enter the lungs, and larger particulates will be cleared to the gastrointestinal (GI) tract. Inhalation, ingestion and dermal contact can all lead to the chemical entering the blood stream and impacting a target organ, causing potential physical health effects.

Figure 1: Conceptual model of landfill exposure sources and pathways (1)

This figure depicts that landfill exposure could come from leaching and infiltration into land and water as well as gas migration and dust emissions. This could lead to a range of pathways of exposure from surface run-off, volatilisation from water or the landfill, or direct human contact with contaminated land, soil, water or air.

Odour

Odour may be generated by the waste as it is being tipped, and often when it has become saturated due to high-intensity rainfall overwhelming the surface water management system, becoming contaminated and having to be treated as leachate. In this scenario the leachate plant may not have adequate capacity to deal with the volume of water. This allows for water level rise within the site, leading to odour generation. There is anecdotal evidence that saturated waste provides ideal conditions for sulphate-reducing bacteria to thrive and produce hydrogen sulphide (H2S). Both short and long-term exposure to odour from industrial sources (olfactory nuisance), is little studied compared to the large number of studies on the toxicity of chemicals inhaled from landfill sites.

Odour sensations processed in the central nervous system may induce pleasant reactions, positive mood and emotions, but also negative responses including irritation, pain, sneezing, salivation, and vasodilation (widening of blood vessels causing nausea and fainting), ultimately resulting in nasal obstruction, bronchoconstriction, mucus secretion and inflammation (2).

Malodours, or bad air quality have been considered as environmental triggers of headaches, eye irritation, nausea, dizziness, and unusual tiredness, even when the substances that cause the odour are themselves not toxicologically harmful to health.听It is also important to note, that individuals鈥� sensory responses can vary due to physiological factors, age or sex, persistent exposure, perceived health risk, and various social factors (2, 3). Odour-related symptoms seem more common in subjects with odour intolerance (4)聽and is mediated by personal perception or annoyance.

At elevated concentrations, odorant receptors may send signals via the olfactory and trigeminal nerve to the brain causing subjective symptoms. Gong and others (5) noted that annoyance can cause the release of catecholamines from the hypothalamic-pituitary-adrenal axis, increasing the risk of high stress hormone exposure.听This prolonged exposure can lead to mental health disorders and physical problems such as impact on sleeping, all which in turn may lead to other, secondary physical diseases such as cardiovascular disease, respiratory disease, and sleep disorders.

Chemical releases: assessing potential impacts upon public health

Chemicals potentially released from landfill sites聽聽聽

Wastes deposited at landfill sites contain an almost infinite number of different chemical sources, as they can contain plastics, clothing, electrical appliances, oils, building materials, paints, furnishings, packaging and so on, each of which contains multiple different chemicals. Coupled with this, degradation processes will create other substances, not just methane and carbon dioxide, but also volatile chlorinated chemicals and other organics.听聽聽聽

The provides a comprehensive description of the types of substances that may be released from landfill sites. In addition, the EA provides guidance on monitoring for a wide range of chemicals.

The monitoring requirements are therefore part of the environmental permit and should consider as a minimum groundwater and surface water impaction by leachate, greenhouse gas emissions, dust, vermin, noise and odour.

Odours potentially released from landfill sites聽聽聽

Odours are caused by a number of chemicals released as gasses.听Some chemicals are not detectable by the human nose (olfactory senses), and as such some can pose a toxicological risk without generating odour. Conversely, there are compounds which generate odours (odourants), which can be smelt at very low concentrations, while presenting a low or no toxicological health risk. However, it should be noted that certain compounds can be both an odourant and pose a toxicological risk at a low concentration.

Odour from landfill sites is regulated under an odour management plan as part of conditions imposed by the site鈥檚 environmental permit; thus, active landfills will have a monitoring plan, which will look at odour intensity and hedonic (pleasant or unpleasant) tone. Gasses from landfills that may affect public health are expected to be picked up by gas monitoring on site.听

The common gasses, methane (CH₄) and carbon dioxide (CO₂), are odourless. However, sulphur compounds from landfills are the main source of odour.

Population group impact

Any population near a landfill is a vulnerable group.听A population, or members of a population, may be vulnerable due to environmental conditions such as location, the current quality of the setting, housing quality and resources such as access to medical care.听deFur and others (2007) (6) noted that individuals can be vulnerable due to social factors, biological factors (for example genetics or gender), age, physical health (for example asthma or other pre-existing medical conditions), mental health and temperament (sensitivity, for example).

How and when UKHSA becomes involved

Commonly, UKHSA will be notified by the EA or the local authority, regarding a release or emission noted at a site, or that they, as regulators, have received complaints.听We can be asked to provide public health advice on monitoring data, emissions, and potential exposure to the public.

Incidents are generally related to the potential for short-term acute effects, while complaints generally relate to more protracted (long-term) events.

We may provide information on the toxic effects and the levels of concern for a chemical if known or can carry out a cluster study looking for illness or disease in the vicinity of the site.听This can be coupled with modelling of the potential for emissions or releases from the site to assess risk.

Our methodology for cluster studies was published as Guidance for investigating non-infectious disease clusters from potential environmental causes by Public Health England.

UK health studies up to 2009

The considered health evidence in literature published up to 2009, and it is relevant to summarise the evidence base of these health investigations as a background to this current update.

The HPA review particularly focussed on European and UK epidemiological studies which were described as ecological studies. These are investigations which looked at populations living in the vicinity of landfill sites and comparing their health status to a reference population, for example those living further away or living in a wider defined area, such as a county. There is an assumption that there is a difference between these populations in levels of exposure to whatever arises from landfill sites.听聽

There are several methodological differences in these types of studies which were described by the and covered in the . In summary, these studies cannot say whether a landfill caused a particular health effect but may give an indication of areas of investigation worth following. Additionally, studies carried out before 2009 were conducted around a population of landfill sites which may bear little resemblance to the ways in which landfills are operated and regulated today; the relevance of the findings to current landfill operating practices and their impact on public health must be viewed in that context.听聽

The 3 main batches of ecological studies which were produced in this earlier period were those conducted by the European project called EUROHAZCON, by the Small Area Health Statistics Unit (SAHSU) at Imperial College, London and from a study of sites in Wales.听

EUROHAZCON studies

This investigation focussed on hazardous waste sites in Europe and the UK, that is, those sites accepting chemicals of high toxicity as these were thought to constitute the greatest health risk to nearby populations.

Dolk and co-workers (1998) (7) in a study of 5 European countries (including the UK) found a higher incidence of non-congenital chromosomal abnormalities in babies whose mothers lived closer to landfill sites than those who lived further away.听Subsequently, Vrijheid and others (2002a) (8) reported an increased incidence of birth defects due to chromosomal congenital anomalies (including Down鈥檚 syndrome) in babies whose mothers lived close to hazardous waste landfill sites. Morgan and others (2004) (9) investigated the risk of low birth weight near the 10 EUROHAZCON sites in England and found a small, non-statistically significant increase in the risk of low birth weight within 3km of the sites. 聽

SAHSU studies

In response to the concerns raised by the EUROHAZCON findings, SAHSU was commissioned by several UK government departments to carry out studies of birth defects (and also of certain cancers) in the vicinity of both open and closed landfill sites. This large study identified over 19,000 such sites in England, Scotland and Wales and found that most of the population lived within a few kilometres of a site. The study found a small increase in congenital anomalies in populations living close to landfill sites, but the increase (1% higher than the reference population for all sites, but 7% around hazardous waste sites) was much smaller than had been reported in the EUROHAZCON study. With respect to specific anomalies, an increased incidence close to the sites was seen for neural tube defects, hypospadias/epispadias (defects of the penis) and abdominal wall defects. An increased risk of low birth weight was also seen in the study population (10). Jarup and others (2007) (11), however, found no increased risk of Down鈥檚 syndrome in babies born to mothers living near 6,829 landfill sites in England and Wales, in line with a similar finding in an earlier study in Scotland by Morris and others (2003) (12).

The SAHSU team also found no excess risk of leukaemia and cancers of the liver, bladder and brain in the population living close to landfill sites (13).

Investigation of sites in Wales

In 1996, residents living in the wards near the Nant-y-Gwyddon landfill site voiced increasing concerns that odours from the landfill site were causing illnesses. In terms of birth outcomes, investigations by Fielder and others (2000) (14) revealed no consistent differences in proportion of low birthweight infants between locations experiencing odour and those that did not. While there was an increased maternal risk of having a baby with a congenital abnormality in residents near the site, this increased risk was also apparent before the site opened, suggesting another factor of influence.听

Subsequent investigation in 2005 (15) studied whether the opening of new landfills in Wales was associated with increased rates of congenital anomalies in nearby residents by comparing rates before and after sites opened. Inconclusive results were found for the 20 sites studied 鈥� for the period 1983 and 1997 there was a 39% increase in the rate of anomalies in populations living close to the sites after they opened, whereas for sites that opened between 1998 to 2000, the authors found no increased risk of congenital anomalies.

Commentary on earlier UK studies

This batch of ecological studies was conducted using small area statistical information, using postcode data to identify individuals鈥� place of residence matched to data in registers of ill health and routinely collected health statistics.听The main methodological criticism of these types of studies is that there is no measurement of an individual鈥檚 exposure, with proximity to the site being used as a surrogate measure. Additionally, differences between the comparison populations (near vs further away), such as socioeconomic deprivation, are done on a group level and not on an individual level. Also, these types of studies do not collect individual data such as a family history of disease, lifestyle factors such as smoking, use of medicines or occupation, each which might themselves be associated with the health outcomes being studied. There may also be limitations in some of the health statistics data sets used in the study. The Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment identified the above limitations and concluded that it was not possible to discriminate effects due to confounders and bias from those which might be causally associated with the hazard under investigation and there is little value in undertaking further studies of this type on landfills ().

Other studies conducted prior to 2009

Other epidemiological studies of landfill sites conducted prior to 2009 have been summarised in reviews carried out on cancer incidence, (16) and on self-reported health symptoms (17). Porta and colleagues retrieved 32 publications relating to waste disposal activities (landfills and incineration) and health effects in nearby communities. The authors concluded that there was inadequate evidence of an increased risk of several cancers (11 types in total studies) and of respiratory disease and limited evidence of birth outcomes. This review included the UK studies considered above.

Vrijheid (2000) (17) reviewed the health effects of residence near hazardous waste sites and noted an increased prevalence of self-reported health symptoms such as fatigue, sleepiness and headaches in 10 of the reviewed papers.

Many of these older investigations studied populations living near to, or on, old and poorly controlled waste sites with clear evidence of odour and leakage of noxious chemicals rather than controlled landfill sites. Where specific landfill sites were studied, it is not clear how far the results are applicable to UK non-hazardous landfill sites in general.

Review of evidence since 2009

Introduction

This update was necessary as the previous report had become out of date, subsequent studies had been conducted and methods of landfilling have changed over time.听The update has sought to synthesise evidence on potential health risks associated with living near or on municipal landfills with the aim to identify specific health outcomes.

The previous report only considered physical health, but in the intervening period there has been an increased focus on mental health and on stressor considerations.听

However, as with the previous report, the epidemiological studies carried out, used routinely collected data to compare the incidence of an adverse health outcome in the population living around a landfill site, or around a number of landfill sites, to the incidence in a reference area, such as the rest of the region or country. This type of epidemiological study is usually termed an ecological study.

There are methodological problems with . Such a study can only explore whether there is an association between potential exposures and the health effect under investigation. It cannot say whether or not the landfill site(s) caused the adverse health outcome (that is, whether the association is 鈥榗ausal鈥�). In addition, there is no assessment of whether the study population is subject to harmful exposures. It is assumed that those living near the landfill site are 鈥榚xposed鈥� and those living further away are 鈥榰nexposed鈥�. A further limitation is that this type of study can only make adjustments for other differences between the exposed and reference populations, such as socioeconomic deprivation, on a group level and not on an individual level. They cannot adjust explicitly for confounders such as family history of disease, or lifestyle factors such as smoking, use of medicines and occupation, which might themselves be associated with the health outcomes being studied and which are unlikely to be completely accounted for by adjusting for deprivation alone.

Therefore, there is a possibility that differences in the incidence of health outcome between the study and reference populations are due to one or more of these factors, and not to the landfill site(s). There may also be limitations in some of the health statistics data sets used in the study.

Search limitation

The literature review of the health effects for the previous study was carried out up to 2009.听Therefore, this study was conducted from 2010 to September 2021. The searches were conducted using OpenGrey and Toxnet (2010 to 2019) and Toxline (2019 to 2021).听The study excluded all non-English literature and all waste that was not landfill (such as incinerators or energy from waste).

A total of 16,568 papers were obtained from the search, and screened for duplicates, by title and abstract, resulting in 106 papers for screening by full text. Of these, 37 papers were included for qualitative analysis.

Data exclusion

Although waste transport and transfer into the landfill is a potential health effect due to emissions, and occupational exposure to landfill operatives is considered in some papers, much of this is already regulated and discussed by other UK bodies such as the Health and Safety Executive (18, 19).

We also excluded waste fires and the impact of landfill flooding and erosion based on existing guidance (20, 21).

The risk from landfills currently undergoing coastal erosion or flooding on the coast is a specific pathway and not a population wide risk.听There are more than 1,200 historic landfills in coastal areas in England which are at risk of flooding and erosion, and this is likely to increase in the future as a consequence of sea level rise and climate change. For public health there is a dermal and ingestion risk if eroding waste (solid and liquid) is handled, but there are no recognised methods to assess the impact of eroding wastes into the marine environment.

Health impact review

After screening, we identified papers in the categories of morbidity, health effects, illness, poisoning, cancer, cardiovascular disease (CVD), headache, adverse birth outcomes and mental health. After the full review of the papers, we identified papers in the categories of:

• morbidity
• illness
• health effects
• poisoning
• adverse birth outcomes
• CVD
• cancer
• mental health

They are discussed in their individual categories, then as an overall discussion, as some categories overlap.

Morbidity

The majority of studies considered cancer mortality, rather than morbidity so this is considered further below. However, when studies were adjusted for confounders such as gender, age and social deprivation, there was no link between morbidity and the presence of a landfill.

Health effects, illness, poisoning

The majority of studies were based on the proximity to an active landfill site versus health records, but confounders were often present including other industrialised sources.听A number of papers considered gender, age, education, socio-economic status and so on, but this did not account for all confounders or lifestyle choices. This is highlighted by the Salerno paper (22) that identified hepatitis in women as statistically significant for proximity to landfill; indicating other factors are in play, not related to landfilling.

Overall, some of the studies indicate some evidence of adverse health effects with exposure to landfill sites. However, the methods of data collection and lack of ability to determine a direct causal relationship combined with mixed and limited evidence mean it is not possible to draw any conclusions regarding landfills causing adverse health effects although it may increase the risk of respiratory disease.听What is indicated, is that areas with a population close to landfills are already exposed to other sources and other health impacts, thus the risk of exacerbating symptoms by landfills (such as increasing the risk of severity of asthma) is possible.

Cancer

The previous SAHSU studies found no excess risk of leukaemia and cancers of the liver, bladder and brain in the population living close to landfill sites.

A number of studies have subsequently looked at the risk of cancer from landfill sites, although some were in heavily industrialised areas with other sources present.听A variety of cancers were studied including lung cancer, laryngeal cancer, gastric, colorectal, liver, kidney, and bladder cancer.听One paper from Finland discussed the evidence for living on a capped landfill and found no increase in cancer with those living on or off the landfill over a 5 year period (23).听

Therefore, there is no clear evidence for associations between landfill exposure and cancers, but again the papers highlight the potential for other sources of cancer to be found around industrial areas.

Adverse birth outcomes

The previous EUROHAZCON studies for England had found a small, non-statistically significant increase in the risk of low birth weight within 3 km of hazardous sites (not municipal waste sites as with this study).听The further SAHSU work looked at 19,000 both open and closed landfill sites, and both hazardous and non-hazardous sites in the UK. The study found a small increase in congenital anomalies in populations living close to landfill sites where the waste was hazardous or unknown.

聽A number of subsequent studies have additionally considered congenital birth malformations but have identified no or minimal risk of birth defects around municipal landfills, but a stronger link with deprivation.听

Cardiovascular disease (CVD)

The papers that were identified under this search function did not contain evidence of CVD in relation to landfills.听 聽聽

Mental health

There were very few papers that related to landfills and mental health.听Most either considered hazardous waste sites or general sites with 鈥榗ontamination鈥� which could be used as a proxy for landfill.听The majority of papers also looked at vulnerable people and why they were vulnerable rather than the symptoms.

It is recognised that when environmental contamination in residential communities is present 鈥榟eightened stress and anxiety to the point of dread鈥� may be observed in groups living on or near the contaminated sites. The effect on mental health may be due to the loss of open neighbourhood space, costs and inconvenience in managing individual perceived exposures, litigation processes, house price changes and impacts of remediation strategies, which can all impact mental health as well as the worry of known or unknown potential contaminants.听

The papers concluded that the proximity to landfills was not an important predictor of worry, but the perceived chemicals within the landfill were.

Stressor impacts

Impact on human health is not just from exposure directly from toxic or carcinogenic chemicals.听Stressor compounds such as odour or noise from a landfill can have both physical and mental health effects on the human body regardless of the toxic (or not) nature of the vapour causing the odour.听

Odour or noise is a psychophysical stimulus or 鈥榮tressor鈥� as the population feel they have no control over it.听Stress, including psychological stress is known to compromise health, causing negative psychological and physical reactions.听The biological mechanism underlying annoyance (noise, odour and so on) and mental health relationships is proposed to be the release of stress hormones disrupting hormonal rhythms via activation of the hypothalamic-pituitary-adrenal system.听Dysregulation of the hypothalamic-pituitary-adrenal axis is known to be significantly associated with a variety of mental health disorders, including depression, post-traumatic stress disorder (PTSD) and so on. These in turn may lead to other, secondary physical diseases such as cardiovascular disease, respiratory disease and sleep disorders.

No consistent evidence of the effects of stress on physical outcomes versus the distance to the source of exposure was found in this review.

The majority of studies looking at physical health effects of stressors noted that malodour appeared to have an impact on mood and that residential odour exposure was associated with an increased risk of headache and cough or phlegm, and often an increase in nausea and vomiting.听Dizziness, unnatural fatigue, and joint or muscular pain were also noted in many of the studies reviewed.听Suggestive associations for other expected outcomes investigated (such as asthma, mucus irritation, mood states) showed that evidence is sparse.

Although reports of 鈥榗ough鈥� were significantly associated with odour frequency, no direct link was revealed between lower respiratory complaints and odour frequency after adjustment for odour annoyance.

There is a significant correlation between annoyance and mental health issues (depression, anxiety disorder and general mental health), although there is a lot of variation within the studies.听Similarly, the higher the annoyance, the greater the correlation with psychotropic medication use (for example antidepressants).听

Therefore, odour from waste and landfill gas, and noise from gas engines and equipment on site, need full consideration to avoid becoming an annoyance to some or all of the local population.

Discussion

Physical health impacts

The majority of studies looked at active sites, with a population living within several kilometres.听Very few considered illegal waste sites (which may be similar to historic sites), or a population living upon a surrendered or historic landfill.听

A further consideration was that most of the landfills considered in the studies were in areas with other industries (such as oil refineries and incinerators), likely to have poor air quality and often with residents within a low socio-economic group with the confounders of deprivation.听Generally, it was only the inhalation pathway that was considered (primarily vapour inhalation), and dust.听Odour was not considered within most papers that were considered.

Health effects were statistically identified in areas with high air pollution, where landfills were present with elevated H₂S emissions; however, other emissions from surrounding heavy industry were assumed but not quantified.听In US and Italian studies, self-reported symptoms such as irritation of the skin and the respiratory system were used, and statistically correlated hospital records of respiratory disease and CVD were collated, which could be related to confounders.听

There is no clear evidence for associations between landfill exposure, morbidity, cancers or CVD, but again the papers highlight the potential for other sources of cancer to be found around industrial areas.听Birth defects in proximity to landfills seem to be associated with deprivation rather than the landfill as a source, although there may be some slight risk from hazardous waste sites (outside of this study).

Overall, some of the studies indicate evidence of adverse health effects with exposure to landfill sites. The methods of data collection and lack of ability to determine a direction causal relationship combined with mixed and limited evidence mean it is not possible to draw any strong conclusions regarding landfills causing adverse health effects although there is some evidence for respiratory disease.听Whether this is a result of other industry, air pollution or deprivation is unclear, so the significance of evidence for landfilling being the cause is low.听However, what is indicated is that the risk of exacerbating longstanding symptoms by landfills (such as increasing the risk of an asthma attack) is possible.

Mental health and stressor impacts

The uncertainty caused about unknown risk to those living near to landfill sites may lead to long-term worry causing distress and may pose a risk to mental health and wellbeing, which in turn may escalate to a stressor affecting the hormone system (the hypothalamic-pituitary-adrenal axis) and ultimately cause both mental and physical health effects.听

Studies concerning mental health mostly related to contaminated land rather than just landfill, but there is a significant correlation between annoyance and mental health issues (depression, anxiety disorder and general mental health), although there is a lot of variation within the studies.听Similarly, the higher the annoyance, the greater the correlation with psychotropic medication use (for example antidepressants).听The biological mechanism underlying the annoyance and mental health relationship can eventually become chronic and cause dysregulation of the hypothalamic-pituitary-adrenal axis known to be significantly associated with a variety of mental health disorders, including depression, PTSD and so on.

For stressors causing physical health effects due to stress hormones, the evidence is generally related to self-reported symptoms, which could be down to annoyance rather than stress hormones affecting CVD, blood pressure, and so on.听Evidence on causal directions is still very limited for landfill, but it is clear from other types of sites that 鈥榓nnoyance鈥� caused by noise, odour and perceived risk of chemicals can certainly cause mental health and physical symptoms generated by stress hormones, and may cause health effects in those living in proximity to landfill.

Conclusions and recommendations

The concluded that 鈥渓iving close to a well-managed landfill site does not pose a significant risk to human health鈥�. UKHSA鈥檚 conclusion would be similar: we would consider that living close to a well-managed municipal active or closed landfill site does not pose a significant risk to human health.听While we have data showing that surrendered sites, by the action of licence surrender, do not impact on health, the picture for historic sites is less clear, due to the lack of data and construction details.听However, given their age and assuming a capping that prevents dust and decreases gas emissions, the same statement can be applied.

The papers taken together do not show an increase in birth defects for non-hazardous sites, but there is evidence 鈥� although not statistically proven 鈥� for potential respiratory illnesses, although the majority of studies were in areas with other potential industrial impacts, such as refineries.听What is clear is that proximity to landfill is generally a guide to proximity to traffic emissions, industry emissions and generally lower socio-economic status, as well as other poor outcome factors; the increased hepatitis and Alzheimer鈥檚 disease identified by Salerno and others (2018) (22) indicates that other health inequalities are at play.

A well-run active site should therefore not pose a health risk. However, issues of offsite odour, dust, traffic concerns, or unknown chemicals and waste types may all cause 鈥榓nnoyance鈥� and increased stress hormones, leading to mental and physical health effects.听Therefore, good communication from the site owners to residents, and from the regulator of the environmental permit to residents is crucial. There needs to be a level of trust with both the site owner and regulator, such that timely investigation of complaints is carried out and there is open communication.听Although the environmental permit concentrates on health and water resources and environment, the dust and odour nuisance are the areas that impact the public more frequently and can lead to distrust of the site and regulator. Therefore, it is possible that these areas should be considered further in the development of any new landfill sites.

Although the data and health effects from historic sites is less clear, these are often maintained as 鈥榞reen space鈥� and as they do not look like landfill, the risk of 鈥榓nnoyance鈥� is much lower.听However, misinformation may impact mental health and any monitoring without communication to the public may increase stress.

Based mainly on H₂S concentrations, modelled for dispersion, there is the potential for H₂S to be the cause of respiratory problems.听While the evidence is not strong currently, there is a potential for a causal relationship.听This may be an emission that could be monitored more frequently around landfill.

Acknowledgements

Lead authors:

• Sarah Dack
• Emily Cheek
• Sian Morrow

Contributing authors:

• Daniel Medlock
• Alec Dobney

The authors wish to thank Andrew Kibble, Greg Hodgson and the EA for comments on this report.

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