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Dioxins Hong Kong proposed Incinerator

From: Prof AJ Hedley/School of Public Health, HKU []
Sent: Thursday, January 05, 2012 15:14

To:     John Schofield (email:
Treasurer, Living Islands Movement
Cc:     Professor TW Wong, School of Public Health, Chinese University of Hong Kong
From:   Anthony Hedley
Date:   January 5, 2012

Dear Mr Schofield,

Thankyou for your letter and apologies for the slow response.  I was working in a medical school in Thailand and then transferring to Hong Kong where I will be until 20 January.

I do not claim to be an expert on the technology of incinerators although I try and follow the developments in that field.  Jim Middleton (“Clear The Air”) and others have maintained a useful flow of bulletins on that issue.  As a medical practitioner and public health specialist I have an interest in exposure assessment to dioxins and dioxin-like compounds and we have done some work in that field in recent years.  A complete set of the papers we have published so far on persistent organic pollutants is attached.  They are necessarily quite technical and may not be very useful to you.  However a one page executive summary has potentially helpful diagrams and text and the paper in “Environmental Health Perspectives” conveys some of our concerns about dioxin control, albeit from a 5 year old perspective.  They show where Hong Kong is in terms of its risk status with regard to dioxins and PCBs.

The dioxin level in human breast milk is the best and most relevant indicator of past exposure of a population or its subgroups.  It is relevant because young primagravidae (first pregnancy mothers) pass on their dioxin load to the infant during gestation and then “top it up” if they breast feed.  We usually get a large proportion of our dioxin load from our mothers, which may then be added to through the dioxin content of our diet.  So the trans generational effect should be seen as an important reason for contemporary civic responsibility.  Humans are particularly susceptible to environmental persistent organic pollutants because they are amplified in the food chain and lipophilic, so stored in body fat rather than being eliminated.

One point I should make emphatically is that we have made a special effort to ensure that although breast milk is a conduit for dioxin from mother to infant, this must not be regarded as a reason not to breast feed.  The evidence which is available suggests that breast milk is likely to protect against adverse effects at least to some extent.  This may appear to be an uncomfortable paradox but it is the best position to adopt for many reasons.

The World Health Organization (WHO) has run 3 global surveys so far on dioxin in breast milk.  We joined the 3rd one in 2001/02 with funding from the Conservancy Association.  This was the first time Hong Kong participated, although a paediatric research group (Dr Henrietta Ip) had done studies in the late 1970s and 1980s.  Comparisons between studies to identify trends are hazardous because the assays were done in different laboratories.  (Our data were generated in the WHO reference laboratory in Freiburg, the only lab with the credentials to do this in the global survey).  However it would be fairly safe to say that over the years the levels of most pollutants had declined in Hong Kong mothers possibly due in part to the closure of old incinerators as well as other regional and global regulations and controls on PCBs and sources of dioxins.

A new survey has just been completed by my colleague Professor TW Wong at Chinese University School of Public Health.  I am copying this to him so that he might add to my comments and perhaps summarize the findings of this latest data.  We have jointly applied for funding to follow-up the infants born to our 2001 mothers, but no decision yet.

My summary comments in an effort to address your questions would be:

1.   Hong Kong (and any jurisdiction) should adopt a rigorous precautionary approach to the control of pollutant emissions which bioaccumulate in animal food sources and human tissues.

2.   Dioxin compounds are rated as some of the most highly toxic chemicals in the environment.  They have been shown to be associated with severe damage to the central nervous system, immune system, reproductive and endocrine systems, skin disorders and a cause of cancers.  They are particularly important as “endocrine disruptors” in newborns and infants.

3.   Hong Kong was included in the 3rd WHO global and ranked 14th out of 26th for concentrations [Toxic Equivalents (TEQ) expressed as picograms per gram of fat (pg/g fat)] for polychlorinated benzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF) (ie “Dioxins” and dioxin-like compounds).  Hong Kong ranked 17th out of 26th for concentrations of Polychlorinated Biphenyls (PCB).  The Hong Kong/PRD values were lower than at least half of the other countries in the WHO survey.

However for all of these groups of structurally related chemicals Hong Kong had the highest levels in the Asia Pacific group which included USA, New Zealand, Australia, Philippines and Fiji.  Hong Kong levels were 40% above those of Australia.

4.   The particular susceptibility of Hong Kong mothers is emphasized by the strong association between age and body levels of dioxin.  Age of mother at age of first pregnancy dominates the risk profiles in terms of higher levels.  Late age at marriage and first pregnancy in Hong Kong means that even relatively lower life-time exposures will lead to substantial bioaccumulation and higher levels of dioxins being transferred to the unborn infant.  This observation emphasizes the need for an integrated environmental and public health approach, something which the present Environment Bureau may be incapable of achieving.

5.   Emissions of persistent pollutants contaminate both land and marine based sources of food at the lower end of the food chain.

Arguments based on emissions being “blown away” by prevailing winds are scientifically unacceptable and seriously misleading if they are allowed to influence policy making.  I understand these are suggestions made by EPD/EB staff to rationalize the project on Shek Wu Chau.

6.   The lower than average (or median) detected levels of dioxins in our survey are encouraging but extreme vigilance is required to ensure than further progress is maintained.  However in our paper in Environmental Health Perspectives 2006 we wrote:

“the public health threat of dioxin contamination in this region remains a concern.  The dioxin inventory in mainland China for 2002, the first so far, estimated PCDD/PCDF emissions to the atmosphere to be 7,144-13.575g International (I)-TEQ/year (Jun et al. 2004).  The China inventory does not include uncontrolled backyard burning of waste.  In Hong Kong, the annual emission was estimated to be 23-33 I-TEQ/year (HKEPD 2000).  One main reason for the high dioxin emission in mainland China is the heavy municipal waste management burden, together with its expanding population.  Most of the municipal waste incinerators in mainland China did not comply with the PCDD/PCDF national emission standard of 1.0 ng 1-TEQ/m3, which is less stringent than 0.1 ng 1-TEQ/m3 used in developed countries (Jun et al. 2004).  The growth of the economy was associated with the development of industries causing dioxin emissions, such as crude steel and chloralkali industries.  Active dioxin abatement policies and measures are needed to enforce a more stringent PCDD/PCDF emission standard for incineration, control illegal smuggling of electronics waste (Basel Action Network 2004; Schmidt 2002) for recycling activities and prohibit uncontrolled waste burning and ensure correct disposal of equipment and material containing PCBs.”

These caveats about mainland China can and should obviously apply to Hong Kong today.  In 2006 we assumed that any incineration technology adopted in Hong Kong would be state-of-the-art and ensure that pollutant emissions were minimized to the greatest possible extent.

This now appears not to be the case and is unacceptable from a public health viewpoint.  This is especially so, given that the EPD is apparently defaulting to depending on air movement to mitigate the impact of emissions locally and will only monitor mass concentrations four times a year.

7.   From an overall project management point of view I also would want to see an EIA which takes account of the high volume of marine traffic which will be needed to transfer waste to Shek Wu Chau.  If present types of fuel oil are used to power these vessels they will add another layer to pollution of Hong Kong’s inshore waters.

8.   At a personal level, from both an ecological and aesthetic point of view I would be implacably opposed to further despoiling of the seascapes in this part of the Hong Kong archipelago.  I cannot image how an option appraisal led to this choice.


My strong recommendation is that the further development of incineration should be based on advanced technology, particularly high temperature systems which destroy important toxins; rigorous independent environmental impact assessment; adoption of the precautionary principle; clear pathways for ministerial and bureaucratic accountability (almost totally lacking in environmental matters at present) and failsafe continuous monitoring linked to mechanisms for totally independent oversight of this aspect of environmental management.

The Environment Bureau should recognize that there is a total loss of public confidence in its current management practice and the incinerator proposal is a new entrant in this category.

I will help if I can, though my available time is severely limited at present because of many other commitments.  Also the public health concerns are clear and unambiguous: there should be the maximum possible reduction of all combustion emissions from waste incineration and the maximum possible reduction of waste generation on the shortest possible timescale.  I am concerned that Professor Northcote Parkinson’s satirical law, “Demand expands to fill capacity”, may be the main outcome of building a so-called super incinerator.

In the meantime please see if the Executive Summary (single sheet) and the paper in Environmental Health Perspectives lead to any further queries which we might try and answer.  Note these papers are the first two attachments.

With best regards,

Anthony J Hedley MD FRCP
Tel: 2819 9282 (Secretary Marie Chi)

1_executive summary






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