Rapid Responses to:
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Rapid Responses: Rapid Responses published:
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other factors?
- Edmund Kingston (17 August 2001)
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Paternalistic, illogical reassurance
- Mitzi Blennerhassett (18 August 2001)
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Length of residence.
- Gareth Lloyd (19 August 2001)
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Socioeconomic factors of landfill sites
- Geoff Helliwell (19 August 2001)
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Oxygen
- Patricia Theisen (19 August 2001)
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Alternative presentation of risks from landfill sites
- Dick Heller (20 August 2001)
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Anomaly Notification Data Are Suspect
- Nick Payne (24 August 2001)
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What a load of landfill!
- Lydia Morton (24 August 2001)
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other confounders
- H Gregor Rigo (27 August 2001)
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The evidence suggests it is probably safe for fetuses to develop near landfill sites
- Helene Irvine, Harry Burns (12 September 2001)
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landfill site study - quality of data
- Patrica Boyd (18 September 2001)
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Person-specific risk factors
- Julia Macleod (22 September 2001)
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Landfill sites and low birth weight
- Jonas F Ludvigsson (19 October 2001)
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Possible Causes of defects
- Chris Massie (26 October 2001)
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An association between paternal agricultural work and hypospadias: Are endocrine disruptors playing
- Bianchi Fabrizio (30 November 2001)
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Edmund Kingston
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having read this report I have one question: How much does socio economic factors effect this report. It seem to me that the percentage of low quality housing near to a landfill site would be higher and therefore this could be a factor in the percentages. |
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Mitzi Blennerhassett, secretary cancer concern support group, royal college patient liaison group member home
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The official response to this finding was that smoking and drinking gave a far greater risk percentage of birth defects. What they failed to add was that smoking and drinking are optional. |
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Gareth Lloyd, retired
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The duration of residence near to land-fill sites of mothers of the infants studied is not clearly stated in this study. Increased duration of residence may increase the potential risk of abnormalities at birth. It is also difficult to understand the reason for a 2 Kilometer distance for the control group excepting a need to provide some kind of control however unuseful. Measurement of wind-drift should be taken into consideration. Also there have to be land-fill sites which are sufficiently far apart to provide extending concentric distances for control groups which would provide a distance related relaltionship. Evidence from much smaller and differently conducted sudies are needed. large is not always beautiful. |
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Geoff Helliwell, Consultant Occupational Physician WellWork Ltd.
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The question of what type of housing is found next to Landfill sites is entirely similar to the question of "Wire Codes" in the initial investigation of the health effects of Power Frequency Electro-Magnetic Fields (EMF). Residences were coded by how close they were to low,medium and high voltage overhead power lines and transformers/switchgear. There was a strong correlation of Childhood Leukaemias to wire codes, which then disappeared when actual EMF measurements were used rather than the codes. The "wire coding" was shown to be a surrogate marker for social deprivation and lower Socio-economic status. Often the EMF levels were dependent on other factors such as the earthing configuration of household electrical installations (e.g. water pipes) rather than distance from Power Fields.
The Environment Agency must go on to look for possible noxious agents, make actual measurements, and then correlate them with the experienced birth defects. Reference : Savitz D, et al. Case-Control study of childhood cancer and 60-Hz magnetic fields. Amerian Journal of Epidemiology 1988 Vol 128 p 21-38 (Competing Interest - provision of Occupational Health to DEFRA UK Land Fill disposal site for FMD Carcasses) |
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Patricia Theisen, Perceptual Specialist India
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Has anyone measured the ion particle content of the air around landfills? With all the plastic eroding the oxygen must be very polluted. If the ion count ratio is off balance the oxygen that the mother is breathing could be inert which would seriously affect the health of the developing fetus. |
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Dick Heller, Professor of Public Health Evidence for Population Health Unit, Medical School, University of Manchester
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The presentation of risks in relative terms does not help the individual, or the population, to understand the risk to themselves. Let's assume that the risks identified by Elliott and colleagues are not due to unmeasured confounding. By taking the absolute risk in the reference area into account, we can translate the relative risk of 1.01 for all anomalies combined to one extra anomaly among 5903 who were exposed to living within 2km of a landifill site. This can be set against the baseline population risk of one anomaly among each 59 individuals. The relative risk of 1.05 for neural tube defects can similarly be expressed as one extra defect among 35,714 exposed, against the baseline risk of one per 1786 in the general population. Extending this further, we can calculate the number of the total population amongst whom one extra anomaly will be produced by the presence of ladfill sites (to which 55% of the population are exposed within 2km) - this is termed the Population Impact Number (PIN)[1]. For all anomalies it is 10,733 and for spina bifida it is 64,935. Should the evidence be thought to be robust enough, the individual and the community can use terms beyond the relative risk to help with decision making. [1] Heller RF, Dobson AJ. Disease impact number and population impact number: a population perspective to measures of risk and benefit. Br Med J 2000;321:950-952. |
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Nick Payne, Consultant in Public Health Medicine North Derbyshire Health Authority
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Given the very small excess risk shown in this study, more attention needs to be paid to the quality of the data collected by the National Congenital Anomaly System. The number of registrations of anomalies has been show to be unreliable and highly dependant on who is responsible for returning these registrations.(1) This is less of a problem for the main reason the notification system was set up, namely to detect a rise in numbers over time due to a new exposure, such as occurred with thalidomide. However, this present study did not find clear evidence of such a rise from before opening to during operation or closure of landfill sites The possibility that the apparent effect might be due to problems with the notification system data must be taken very seriously. References 1. Payne J.N. (1992). Limitations of the OPCS congenital malformation notification system illustrated by examination of congenital malformations of the cardiovascular system in Districts within the Trent Region. Public Health 106:437-448. |
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Lydia Morton, 3rd Year Medical Student Department of Epidemiology and Public Health, The Medical School, University of Newcastle.
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Dear Sir The recent ambitious study by Elliott et al (1) aimed to investigate the risk of adverse birth outcomes associated with residence near landfill sites in Great Britain. The results of a study as large as this could have important implications on environmental health policy. The authors considered residency within 2km of a landfill site as a measure of exposure, based on WHO guidelines. This is of limited value as specific levels of toxins or chemicals were not recorded. Similarly, geographical and meteorological factors were not taken into account. The exact site and size of the landfill sites were not considered, with different reference points being used, i.e. distances being taken from either the centre point or perimeter. Therefore, inconsistency existed within the study population. Residency was the only factor accounted for and controls were assumed to be exposure free. However, there is a possibility of controls being significantly exposed e.g. through employment within 2km of the landfill site. Results were adjusted for deprivation according to postcode, although other risk factors were not analysed e.g. smoking, air pollution, diet. These could influence the aetiology of adverse birth outcomes. This study has identified that there is a slight increased risk of certain adverse birth outcomes in the population living near landfill sites. Due to the limitations of the methods, further investigations are required to establish a causal association and quantify the impact on health. Whilst an exhaustive study such as this provides extensive population data, it is not specific enough to implicate changes in public health policy. Yours faithfully Lydia Morton, Rebecca Preece, Johanna Raker, Ruth Sharrock. Department of Epidemiology and Public Health, The Medical School, University of Newcastle upon Tyne, Newcastle NE2 4HH, UK. (1) Elliott P, Briggs D, Morris S, deHoogh C, Hurt C, Jensen TK, Maitland I, Richardson S, Wakefield J, Jarup L. Risk of adverse birth outcomes in populations living near landfill sites. BMJ 2001; 323: 363- 368. |
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H Gregor Rigo, president RRAI
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An interesting piece of work that I see as being a justification for further research. The observations do not, however, form an adequate basis for prudent action since there is no indication that the increases are related to potential exposure. A source can only have an impact if the receptor is down-wind or down-stream. Consequently, the postal codes within the 2km radius need to be subdivided into exposed and unexposed quadrants relative to the source. Different quadrant definitions will probably apply to airborne (gases, fumes and dust) and waterborne (leachate plumes)emissions. Cracks in landfill liners and cover materials tend to predominate emissions, but I have no idea how to determine the existance of such without extensive field studies. It would also be useful to do some sampling to determine the length of time residents typically lived at the address and the duration of exposure mothers had prior to giving birth or terminating their pregnancy. |
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Helene Irvine, Consultant in Public Health Medicine, Director of Public Health Greater Glasgow Health Board, Harry Burns
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Editor- Elliot et al report on a large and long awaited geographical study of risks of adverse birth outcomes in populations living within 2 km of 9565 British mainland landfill sites(1). They conclude that there are small excess risks of congenital anomalies and low and very low birth weight in populations living near landfill sites. Although the authors are careful to add the usual provisos and advise caution when interpreting their results, the study is nevertheless hailed by the popular press and by pressure groups as evidence that living near to such sites is hazardous to health(2). The existing concerns felt by mothers, often with no realistic opportunity to move from such sites, are fueled yet again and perhaps on no good grounds. Scientific colleagues contribute to the media - and lay-generated intrigue in subtle ways. For example, the rather explicit description of the paper in an editorial by McNamee and Dolk(3) as a report on the ‘risks to fetuses associated with residence near landfill sites’ when ‘a study of the statistical association between reported anomalies and low birth weight babies and residence near landfill sites’ would have been more accurate and less sensationalistic. Meanwhile, health authorities are left to pick up the pieces when the story about a landfill site in their area breaks with no advance warning. In fact, another interpretation of their results is that this large and essentially negative study goes a substantial way to reassuring other scientists who have been studying this question that it is probably safe for fetuses to develop near to such sites. Any scientist who has any experience of multivariate epidemiological analysis would have to admit that such small and inconsistent excesses and deficits, even though statistically significant could well be, and are probably attributable to inadequately adjusted social deprivation to name but one of many important confounders, including nutrition. Such epidemiological techniques as used in this study are blunt instruments attempting to detect subtle and unidentified effects that may not even exist and serve to add to a burgeoning published literature, that, interpreted by the media, plays on people’s fears. Furthermore, the fact that there was a statistically significant deficit of anomalies, etc. around landfill sites in Scotland and no increase after the British landfill sites became operational must leave even the most determined author feeling uneasy about suggesting a causal association. The previous literature with which this study was reportedly consistent is not itself consistent or persuasive with a recent study also showing no effect after a landfill site became operational(4). The alternative approach to demonstrating a ‘dose response relationship’ that revealed a small 7% excess of birth defects, etc. around hazardous waste landfill sites could well be reflecting the fact that the privileged tend to avoid living near to such sites, which, in any case, tend to be designed and managed to much stricter specifications than are domestic and commercial landfill sites. Perhaps it is time for epidemiologists to admit that their tools are inadequate to answer this question and encourage other scientists to take this forward by using existing, and developing further, techniques to identify any putative agents in the gas emissions, leachates and soil that are of sufficiently high level to affect human health. Epidemiological studies of statistical association without an hypothesised agent will never settle this long-standing issue. Many of these landfill sites are unattractive and intermittently foul smelling, attracting seagulls and rodents and peppering the landscape with windblown rubbish. More imaginative long-term waste management solutions are long overdue. In addition, more careful consideration should be given to the granting of planning permission for new build housing immediately adjacent to landfill sites. These neighbouring areas often include low cost plots which easily attract contractors keen to make the obvious financial profits and ultimately attract cost-conscious couples equally keen to raise a family in an affordable house(5). Helene Irvine, Consultant in public health medicine, Greater Glasgow Health Board, Glasgow, G3 8YU helene.irvine@gghb.scot.nhs.uk Harry Burns, Director of Public Health, Greater Glasgow Health Board, Glasgow, G3 8YU Competing interests: None 1) Elliot P, Briggs D, Morris S, de Hoogh C, Hurt C, Kild Jensen T, Maitland I, Richardson S, Wakefield J, Jarup L. Risk of adverse birth outcomes in populations living near landfill sites. BMJ 2001;323:363-8. 2) Foster K, Health Correspondent. Landfill sites blamed for birth defects. The Scotsman. 17 August 2001. 3) McNamee R, Dolk H. Editorial: Does exposure to landfill waste harm the fetus? BMJ 2001;323:351-2. 4) Fielder HM, Poon-King CM, Palmer SR, Moss N, Coleman G. Assessment of impact on health of residents living near the Nant -y- Gwyddon landfill site:retrospective analysis. BMJ 2000; 320:19-22. 5) Greater Glasgow Health Board. Investigation of possible ill-health near a landfill site in East Glasgow. Board Paper No. 99/136(b). Presented at Board meeting on 16 November 1999. 644 words |
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Patrica Boyd, geneticist Womes Centre Oxford Radcliffe
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Person-specific risk factors | 22 September 2001 | ||
medical student
University of Newcastle upon Tyne
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Re: Person-specific risk factors
Dear Sir,
We read with interest the recently published study investigating adverse birth outcomes in mothers living near landfill sites. This geographical study aims to provide important nationwide information. However the authors fail to address several important points.
Previous correspondents have outlined the fundamental limitations of this study. We feel the authors failed to adequately evaluate the effect of person-specific risk factors. It was not acknowledged that individuals are not static and are affected by different environmental exposures. Consideration of lifestyle factors such as employment and lifestyle are crucial in quantifying exposure, due to movement within the area. Smoking, alcohol and infections are known to influence birth outcome. Although mentioned, these factors were not individually adjusted for in the analysis.
Elliot et al1 discovered a higher proportion of women of Indian, Bangladeshi and Pakistani origin living within 2 km of landfill sites. As the average birth weight of Bangladeshi and South Indian babies appears small on British height and weight centile charts2, could the small increased risk of low birth weight within the study population be artefactual?
With 80% of the population currently living near landfill sites, would it be feasible to move residents or close existing sites if a high risk were to be found? More importantly, can we really afford to find a causal relationship?
Yours faithfully,
Julia Macleod, Mellissa Hartley and Faye Damant
(j.m.r.macleod@ncl.ac.uk)
4th year medical students, Dept. of Epidemiology and Public Health, Newcastle University Medical School, NE2 4HH.
1- Elliott, P et al. Risk of adverse birth outcomes in populations living near landfill sites. BMJ, 2001; 323: 363-8.
2- Collier, J. Oxford Handbook of Clinical Specialties, Fifth edition; 1999: p.436.
| Landfill sites and low birth weight | 19 October 2001 |
Doctor
Dept. Paediatrics
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Re: Landfill sites and low birth weight
EDITOR – The paper by Elliot et al makes an important contribution to the literature on birth outcome and waste disposal in landfill sites.(1) The results are based on over 8 million live births, hence avoiding the risk of bias from selective reporting. The authors do however note that data quality in this study may not be optimal.
Within the ABIS cohort study we asked mothers with newborn infants to complete a questionnaire on physical and socio-economic data, including distance to the nearest landfill site (ABIS = All Babies in Southeast Sweden). Regression analyses were adjusted for gestational age, maternal age, maternal smoking, exposure to life event during pregnancy (e.g. close relative died, separation from the partner), sex of infant and maternal education. “Distance to landfill site” was graded according to <150m, 151-300m, 301-500 m and >500m. In the regression analyses this distance was dichotomised (*500 m vs. <500 m to landfill site). Crude analyses were based on 10217 infants, regression analyses on 9012 single-birth infants due to missing data among confounders.
Crude birth weight did not differ with distance to landfill site, infants born to mothers living less than 150 m from a landfill site weighed 41g less than infants to mothers living more than 500 m from a landfill site (95% CI = -164, 83g). The risk of low birth weight (LBW<2500g) did not differ with distance to landfill site (*500m: 9/191 vs. >500m: 249/10026, p=0.052). Three out of fifteen women who had indicated that they lived within 150 m from a landfill site gave birth to LBW infants (1400, 2380, 2475g). None of the 191 women living within 500 m from a landfill site reported any congenital anomaly in their offspring.
Adjusting for confounders infants whose mother lived less than 500 m from a landfill site did not weigh less than other infants (-52g, 95% CI = -124, 21g, p=0.161), neither did they suffer an increased risk of LBW (OR = 2.04, 95% CI OR = 0.85-4.94, p=0.112).
Our data are in line with those of Elliot et al., even though the risk increase for LBW in infants whose mother lived within 500 m from a landfill site just failed to reach significance level. Our study is small compared to that of Elliot et al but data were collected from each individual mother through questionnaire. Further studies where distance to landfill sites is more carefully graded are needed.
Jonas F. Ludvigsson, MD for the ABIS study group
Orebro Medical Centre Hospital, Sweden
jonasludvigsson@yahoo.com
1. Elliott P, Briggs D, Morris S, de Hoogh C, Hurt C, Jensen TK, et al. Risk of adverse birth outcomes in populations living near landfill sites. Bmj 2001;323(7309):363-8.
| Possible Causes of defects | 26 October 2001 |
Partner Massie Ludnow & Jenkins, Consulting Engineers
Redruth Cornwall
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Re: Possible Causes of defects
Dear Sir,
This study is but one of several that finds a corrolation between health issues and those living near landfill sites. Little work appears to have been done on trying to establish the causes (birth defects are but one effect, cancers are also a common factor). Some research into the consituents of landfill gas would be appropriate. These are known to contain mercaptans, turpenes, esters and chlorinated and halogenated hydrocarbons. Are the concentrations high enough to cause damage? In addition micro bacterial spores may be released from the decaying organic material. Could these be affecting the health of nearby residents? A recent air quality study here in Cornwall carried out on behalf of Carrick District Council recorded elevated levels of PM10 particles when the United mines landraising dump was in operation. However no chemical or micro bacterial studies were carried out.
The recent EU Directive on landfill at all stages of its development through Committee was recommending a minimum separation distance betwen landfills and residential properties. However the final approved Directive had these minimum distances expurgated and replaced with a vague requirement "distance must be considered". The UK Government need to specify a minimum distance of separation under the Precautionary Principle based on the evidence now available.
| An association between paternal agricultural work and hypospadias: Are endocrine disruptors playing | 30 November 2001 |
Researcher
Institute of Clinical Physiology-CNR, via Moruzzi 1 56124 Pisa
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Re: An association between paternal agricultural work and hypospadias: Are endocrine disruptors playing
An association between paternal agricultural work and hypospadias: Are endocrine disrupters playing a role?
EDITOR, - In a recent study, among several positive risk associations found for congenital anomalies and residence near landfill sites, small but statistically significant risk for hypospadias has been detected.1 A higher similar excess, although not significant, was reported by Dolk et al. around 21 landfill sites in Europe.2 The increased risk for hypospadias is of particular interest in relation to concern about male reproductive abnormalities related to environmental endocrine-disrupting chemicals. 3 Epidemiological attention arises after reports of upward trends of hypospadias rates worldwide, though some artefacts - not yet adequately investigated - may contribute to this trend.4 5 Exposure to agricultural settings has been proposed to be another potential environmental source of such a contamination. An Italian multiregistry study provided the opportunity to explore the association between hypospadias and the parental occupational exposure to pesticides likely to act as endocrine disrupters.
The Italian network of regional registries of birth defects has provided population-based data concerning malformed new-borns and induced abortions, routinely registered by using standardised procedures in accordance with the Eurocat-European Programme guidelines. Cases were infants with isolated hypospadias born during 1992-1998. Controls were healthy male new-borns (North East Italy, Emilia Romagna registries) or with minor congenital malformations (Tuscany, Campania, South West Sicily registries) matched for date of birth and residence area. Parental agricultural work during pregnancy and selected confounding variables were investigated among cases and controls.
Among a total of 1,154,182 consecutive surveyed births, 998 cases (C), 2,636 healthy controls (HC) and 662 malformed controls (MC) were considered. Parents involved in agricultural activities were 72 among cases, 257 among healthy controls and 45 among malformed controls. Maternal agricultural work did not increase the risk both for healthy and sick controls, whereas significant increases emerged for paternal work (adjusting for birthweight, length of gestation, maternal age: ORC-HC 1.94 95% CI 0.95–3.95, ORC-MC 1.92 95% CI 1.02–3.23, pooled OR 1.89 95% CI 1.18–3.05). When stratifying by registries the risk estimation decreases (Mantell-Haenszel OR=1.53; 95% CI 1.02-2.30) as a result of the relevant contribution of Emilia Romagna and Sicily, two registries where agriculture is mainly intensive.
Differences among registries concerning the inclusion criteria of minor hypospadias, lack of information on individual exposure and other potential confounders are, at this stage, the main limitations of the study. An investigation is in progress to retrieve information on deprivation, type/extent of exposure, particulalry concerning endocrine disrupters and residence near landfill sites.
Authors
FABRIZIO BIANCHI
Sezione di Epidemiologia,
Istituto di Fisiologia Clinica del CNR,
56127 Pisa, Italy
e-mail: fabriepi@ifc.cnr.it
NUNZIA LINZALONE
Sezione di Epidemiologia,
Istituto di Fisiologia Clinica del CNR
Pisa, Italy
SEBASTIANO BIANCA
Dipartimento Pediatria, Università
Catania, Italy
ELISA CALZOLARI
Dipartimento Medicina Sperimentale e Dismorfologia, Università
Ferrara, Italy
ISABELLA MAMMI
Dipartimento Pediatria, Università
Padova, Italy
GIOACCHINO SCARANO
Unità Operativa di Genetica Medica, Azienda Ospedaliera
Benevento, Italy
References
1 Elliott P, Briggs D, Morris S, de Hoogh C, Hurt C, Jensen T K, Maitland I, Richardson S, Wakefield J, and Jarup L. Risk of adverse birth outcomes in populations living near landfill sites. BMJ 2001; 323: 363- 368. ( 18 August. )
2 Dolk H, Vrijehid M, Armstrong B, Abramsky L, Bianchi F, Garne E, Nelen V, Robert E, Scott JES, Stone D, Tenconi R. Risk of congenital anomalies near hazardous-waste landfill sites in Europe: the EUROHAZCON study. The Lancet 1998; 352: 423-7.
3 Toppari J, Larsen J, Christiansen P, et al. Male reproductive health and environmental xenoestrogens. Environ Health Perspect 1996; 104 (4): 741-803.
4 Paulozzi LJ. International trends in rates of hypospadias and cryptorchidism. Environ Health Perspect 1999; 107 (4): 297-302.
5 Safe SH. Endocrine disruptors and human health-is there a problem? An update. Environ Health Perspect 2000; 108 (6): 487-93.