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Contaminated soil being examined. Local residents in Hauxton are worried about the potential health impacts from the chemicals involved.

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News investigation Contaminated Bayer site houses get green light despite 'health risks'

Tom Antebi

29th June, 2011

The clean-up of contaminated land earmarked for 380 homes in Cambridgeshire has been 'watered down', according to campaigners, fuelling fears over the potential health impacts of toxic chemicals underground. Tom Antebi reports

Planning permission for 380 new houses to be built on land in Cambridgeshire has been given the go ahead despite allegations of health problems linked to a cocktail of chemicals dumped at the site previously owned by Bayer Cropscience, the Ecologist can reveal.

The contaminated land at Hauxton has seen dumping, leaks and spillages dating back to before the second World War. A number of different agrochemical and pharmaceutical companies have owned it. The site was sold by Bayer in 2004 to Bridgemere UK Plc, the parent company of developer Harrow Estates, and since March 2010 has been subject to a decontamination process, known as remediation.

Harrow Estates is understood to be overseeing remediation and there is no suggestion Bayer is responsible for cleaning up the site.   

Controversially, South Cambridgeshire District Council (SCDC) has recently revised remedial targets after a request from housing developer Harrow Estates Plc, according to local residents. The residents claim the new clean-up requirements are less stringent than those initially agreed. The process, known as ex-situ remediation, involves excavating soil for processing in order to remove the contaminants before returning it to the ground.

Having remediation targets that are less strict will mean that soil excavated from the site for processing will be returned to the ground with levels of Dicamba, Ethofumesate, Bis(2-Chloroethyl)ether, 1,2 – Dichloramethane and Schradan, the five chemicals hardest to remediate, at levels up to 500 times higher than the targets agreed after the initial investigation, conducted by contamination contractor Atkins.

Although the minimum depth of excavation is four metres, in some places it’s seven meters, and there are fears that the ground may be more heavily contaminated than previously thought, the Ecologist was told by one local retired chemist who worked for a number of the companies that have occupied the site, including the chemical and pharmaceutical firm Fisons.

'The amounts of materials in there and the penetration of the ground is much worse than expected’, he told the Ecologist, adding that ‘despite the approval for higher [less strict] remedial targets, we were assured that the groundwater targets, Water Quality Standards and human health targets would be met.’

The chemist also questioned the use of a computer model, known as ConSim, developed by the Environment Agency, and used by clean-up contractor Vertase, to develop these targets, arguing that over-reliance on a computer modelling can be dangerous. ‘When remediated, the site will be covered by just 15cms of crushed concrete which will be the only barrier between the remediated soil and fresh topsoil in the gardens of the planned new houses’, he said. 

Ground-water contamination

A possible health risk could arise due to the groundwater beneath the surface of the site, which lies adjacent to a tributary of the river Cam called the Riddy Brook. There is concern that groundwater containing the chemicals will run into the tributary, and later the river, which runs through a number of towns in the region, including Cambridge. 

Currently, the spread of groundwater out of the site is mitigated by the existence of at least one borehole, through which waste water is pumped into a Waste Water Treatment Plant. This has historically offset both the contamination outside the site boundaries and reduced the groundwater ‘table’ – meaning that the distance between the site surface and the groundwater has been prevented from shrinking to a point where contaminated groundwater seeps to the top layer of soil. 

‘The pumping has continued throughout the remediation process’, said the chemist, ‘but will cease when remediation is complete. So the water table will rise in the event of heavy rain and it is likely the area of contaminated groundwater will spread out, posing a health risk to the new houses.’ 

This will to an extent be offset by a layer of gault clay at least 40 meters thick protecting the major aquifier below the site, and Vertase have argued that any release of chemicals with groundwater will be slow enough to allow a process of natural biodegradation. ‘The stuff down there has been there for over 50 years without much natural remediation occurring. Most of it will end up in the river eventually but it might take a long time’, said the chemist. 

'Vertase admitted after a lot of pressure by people that the groundwater runs in a direction which takes it directly to the river', the former chemist said, but added that a bentonite wall had been built between the plant and the river during the 1970's, to prevent chemicals leaking into the Riddy Brook. However, this has become cracked and damaged over the years, allowing chemicals to contaminate the groundwater.

‘Dangerous and unwise’ for housing

A local pressure group called Hauxair was established to lobby the Council into temporarily halting the remediation works, after a number of people had reported health problems they believed to be caused by exposure to the chemical compounds, also known as Volatile Organic Compounds, or VOCs. Graham Ford, the ex-chair of Hauxair said 'Last summer the stink was awful, at times like living in dry cleaning machine.' According to Hauxair, residents have reported ‘breathing difficulties, sore eyes and throats, burning lips and numb tongues, particularly when the wind blows their way’.

The nature of the chemical compounds has led some to question the suitability of the site for a housing development. Dr Damien Downing, president of the British Society of Ecological Medicine, told the Ecologist 'this is a dangerous proposal, and I consider it unwise to build on this site.’

At a public meeting hosted by Hauxair in June 2010 Dr Downing outlined the potential health affects of exposure to two of the chemicals targeted by the remediation process, Vinylchlorides and Dichlorobenzenes. Citing the American-based Agency for Toxic Substances and Disease Registry, Dr Downing explained that acute effects of a particular type of dichlorobenzene can cause irritation to the eyes, respiratory problems, while acute very high levels can cause headaches, numbness, weakness of limbs. 

At acute high levels, Vinylchloride has been linked to headaches, dizziness, drowsiness and lack of consciousness, Downing said, while extremely high levels can potentially be lethal. Exposure to high levels of vinylchloride have resulted in altered blood flow to the hands, which is manifested as fingers turning blue. This is a symptom that two people reported to have experienced during the meeting.

Although the local chemist told the Ecologist that on the whole he did not consider there to be any significant danger arising from the smells from the site, he did acknowledge that; ‘di-chloramethane isn’t too good. That’s a suspect carcinogen, a lot these compounds are often down as suspect carcinogens, without necessarily much evidence that they’re human carcinogens. Nevertheless they’re still nasty, so you need to take every precaution so that the general public are not exposed to them.’

Local health authorities appear less concerned about the potential harm from the chemicals.

Local officials 'not concerned'

Although no local GPs were available for comment, the Ecologist contacted the Health Protection Agency to request what advice had been given to local GPs in response to the concerns raised by Hauxton residents. In a statement, Dr Lincoln Sargeant, Consultant in Public Health Medicine at NHS Cambridgeshire said ‘it is important to make a distinction between concerns about odour and its nuisance impact and any toxicological effect from exposure to chemicals… these are not good indicators of long-term harm to health’.  He added ‘on the basis of the available monitoring data, the risks to local people from exposure to emissions are very low’.

‘It is unlikely that emissions from the site are going to cause any short term health effects due to the direct effect of the chemicals themselves, such as runny nose, sore throat, breathing difficulties etc, or indeed any longer term health effects,’ he continued.

In a letter from Hauxair to South Cambridgeshire District Council, Graham Ford asked in 2010 ‘if the safe levels for most volatile chemicals are usually well below the level that is detectable to humans, can it be explained more fully how, when the local residents can frequently detect these chemicals by smell, it remains safe?’

The joint response from the Council, the Environment Agency, the HPA and NHS Cambridgeshire told Hauxair that ‘the environmental monitoring data provided to the HPA have been compared to available health based air quality guidelines… where the concentrations in air are shown to be lower than appropriate guidelines, it may be concluded that the risk to health is minimal. For the vast majority of chemicals the odour detection and odour recognition thresholds are below the irritant threshold.’

In a statement, South Cambridgeshire District Council said ‘the site has been granted outline planning permission for residential and mixed use development subject to it being remediated to a standard suitable for these uses. The clean-up is being closely monitored by SCDC and the Environment Agency with advice from the Health Protection Agency to make sure it is being done properly and that it does not pose unacceptable risk to human health or the environment.’

The Environment Agency told the Ecologist that 'our focus has been to ensure that the site is remediated and that the local brook, the River Cam and groundwater are protected from pollution. No housing development will be allowed unless the remediation also resolves any potential risk to human health.’

The Ecologist also contacted Harrow Estates and Vertase FLI but neither entity responded.

Are airborne toxins a health risk?

The local Council, the Environment Agency and the Health Protection Agency have based their arguments that odours should not be confused with toxicological impacts and deemed the air as safe due to air monitoring procedures. However, some have argued that the monitoring techniques employed in the case are insufficient or have misrepresented the levels of airborne toxins.

Part of the regulatory process involves taking air samples to check that airborne compounds do not reach a level high enough to pose a toxicological risk to residents. This is done through the use of ‘diffusion tubes’, which contain a material, known as a sorbent, that can detect levels of chemical compounds.

The allegations of inadequate monitoring were highlighted during a public meeting hosted by the local parish in June 2010. It was argued that the monitoring results were an average which did not show peaks of these chemicals and that the effect of any peak would be mitigated by potential low readings on other days.

Hauxair also argued that the type of sorbent being used was an inadequate form of detection.

South Cambrideshire District Council responded to this by comparing the sorbent being used, called Tenax, with another sorbent called Unicarb. Initially, a Council press release from October of last year stated that there was no difference between the two sorbents, but then after a review of the comparative results the Council released a statement in February this year, saying ‘a comparison of two different types of monitoring tubes measuring chemicals has highlighted that the original tubes using the Tenax sorbent do the job best’.

However, local resident Martin Goldman told the Ecologist the he and other residents have noted occurrences of excessive clouds of vapour released, which are ‘not accounted for by the recorded averaging or intermittent spot-testing done.’  Goldman added that people have been driven out of their gardens due to numb lips, mucous irritation in the nose and headaches that ‘last until leaving the area and then return when coming back’, and says that if the concentrations were as low as claimed by the regulatory bodies, then residents wouldn’t be able to smell them.

The Coucil website addresses this concern, and says ‘in order to identify peak concentrations of chemicals a hand held instrument, a photo-ionisation detector, is being used to measure total volatile organic compounds (TVOCs) in the air…and around the site. Using this method significant TVOCs peaks have not been detected beyond the site boundary.’

No-one accepts liability

According to minutes from a public meeting in June 2010 - seen by the Ecologist - none of the representatives present from the Environment Agency, the Health Protection Agency, Harrow Estates, Vertase and Atkins (who established the original remedial targets after its initial investigation) accepted legal liability for any future health problems arising from the site.

When asked by the Ecologist why Bayer was not forced to clean up the site prior to being sold to Bridgemere UK, the Environment Agency stated ‘all parties are aware that Bayer have liabilities under Part IIA of the Environmental Protection Act 1990 but we understand that Harrow Estates have agreed to be responsible for the remediation.’

Some residents argue a more appropriate use for the site would be a Park-and-Ride terminal, which is due to be relocated. They say there is an opportunity to move the Park-and-Ride to the contaminated site, and build the houses in its place. During the June 2010 public meeting, Jenny Daley, of Harrow Estates, dismissed this suggestion, saying the Bayer site was suitable for housing.

 

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