February 25, 2008



Mr. Luis A. Ubiñas


Ford Foundation
320 East 43rd Street
New York, N.Y. 10017


RE:       Assessment of Dioxin Contamination in the Environment and Human Population in the Vicinity of Da Nang Airbase, Viet Nam


Dear Mr. Ubiñas:


            We thank you for providing us with a copy of the report entitled “Assessment of Dioxin Contamination in the Environment and Human Population in the Vicinity of Da Nang Airbase, Viet Nam,” which was prepared by Hatfield Consultant of West Vancouver, Canada (Hatfield) and Office of the National Committee 33, MONRE in Ha Noi, Viet Nam (Committee 33) and dated April 2007 (Da Nang Report).  The copy was forwarded to us by Hatfield on January 23, 2008. 


The Da Nang Report presents results of the Da Nang Dioxin Assessment and Mitigation Project (DDAMP) funded by Ford Foundation.  This is just one of the greatly appreciated efforts Ford Foundation has made in “helping the people, institutions, and government of Vietnam build a strong, healthy, and vibrant future.”  We wish the Ford Foundation goals - strengthen democratic values, reduce poverty and injustice, promote international cooperation, and advance human achievement – will succeed in Vietnam.


            The Da Nang Report provides, for the first time, significant amounts of data and information regarding one of the presumed dioxin hot spots in Vietnam; however, they do not appear to be adequate to conclude that Agent Orange used during the Vietnam War is the principal source of dioxin or TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) detected during this study and that remediation measures should be implemented immediately to “... protect Vietnamese living in the vicinity of such hot spots from further contamination and associated health impacts.”   On the contrary, they confirm that significant sources of dioxins, i.e. dioxin and dioxin-like compounds, do exist and may possibly pose greater risks for the environment and population in the vicinity of the Da Nang Airbase.  Important findings and associated comments from our review of the Da Nang Report are briefly described below.


1.              The Da Nang Report concludes that “There is no doubt that historical use of the Da Nang Airbase by the US military and their Operation Ranch Hand has resulted in significant dioxin contamination in the environment and human population of Da Nang.  Contamination was widespread during the US-Vietnam war period, particularly in waterbodies and agricultural areas north of the Airbase.”


Recently unclassified documents indicate that damages to trees and vegetable crops in the vicinity of the Da Nang Airbase occurred in September and October 1968 due to widespread distribution of empty 55-gallon drums containing up to 3 gallons of residues.  No damages in the agricultural areas north of the Airbase were reported.  The problems were recognized and addressed in March 1969. 


2.              The Da Nang Report concludes that “Chemical analyses performed in this study confirm that the main source of dioxin contamination at Da Nang Airbase was Agent Orange and other dioxin-contaminated herbicides.”


This conclusion appears to contradict with another conclusion stating that “Other contaminants (including polychlorinated biphenyls [PCBs], organochlorine pesticides and hydrocarbons) were also shown to be present in the environment, both inside and outside the perimeter of Da Nang Airbase.”   This means that other sources of dioxin and dioxin-like compounds do exist both inside and outside the perimeter of the Da Nang Airbase.  At some sampling locations, most of the total toxicity equivalent (TEQ) concentration detected is not TCDD.


3.              The Da Nang Report concludes that “The maximum soil TEQ concentration recorded in this study was 365,000 ppt [parts per trillion]... represents extremely high contamination, and confirms Da Nang Airbase as a significant ‘hot spot’.”


The TEQ concentrations of the samples, particularly those collected from the former Agent Orange Mixing and Loading Area (MLA) and the former Storage Area (SA), do not appear to be consistent with their proximity and distribution.  For example, the samples 06VN063 and 06VN065 are approximately 20 m from the sample 06VN058, but their TEQ concentrations vary unexpectedly.  The TEQ concentration of 06VN058 is 365,000 ppt while the TEQ concentrations of 06VN063 and 06VN065 are 1,200 ppt and 27,900 ppt, respectively.


4.              The Da Nang Report concludes that “Soil dioxin levels from this study confirm contamination data previously obtained by the Vietnamese Government and US EPA [United States Environmental Protection Agency] (unpublished data).”


During a meeting in Ha Noi on July 12, 2006, Committe 33 informed that the Da Nang Airbase is the most contaminated hot spot in Vietnam with an average soil concentration of 10,000 ppt TEQ.  This is significant different than the average concentration of 9 samples collected from the MLA (approximately 106,000 ppt TEQ) and of 9 samples collected from the SA (approximately 27,000 ppt).


5.              The Da Nang Report concludes that “This study (and previous studies conducted by Hatfield/10-80 Division of the Ministry of Health [1998, 2000, 2003, 2005]) has verified that the highest concentrations of Agent Orange dioxin in soil/sediments in Viet Nam are found in the top 10 cm layer; some contaminations is found at deeper strata (e.g., > 30 cm), but only in limited areas on the former Mixing and Loading Area and former Storage Area at Da Nang Airbase (Figure 3.4, Figure 3.5, Figure 3.7).”


The fact that dioxin has been found at highest concentrations in the top 10 cm layer and at significant lower concentrations at deeper strata suggests that its sources are relatively recent because Agent Orange dioxin was probably washed away by decades of runoff.


6.              The Da Nang Report concludes that “The human population of Da Nang is therefore exposed to dioxin from contaminated food, and likely also absorbs dioxin through the skin as a result of direct exposure to contaminated soils and sediments (and possibly contaminated dust).”


This conclusion contradicts with other conclusions stating that “At present, it is believed that only small proportion of the general population of Da Nang City is adversely affected” (22 Airbase workers in approximately 750,000 residents of Da Nang City), and that “The major run-off from the Da Nang Airbase hot spots appears to settle in Sen Lake, and likely does not adversely impact the environment outside the northern end of the Airbase.”


7.              The Da Nang Report concludes that “The highest TCDD level was recorded in a 42-year-old male who has lived and consumed fish from the Sen Lake since 1990.  His TCDD level was 1,150 ppt TCDD (1,220 ppt TEQ; 94% TCDD), indicating Agent Orange as the source of the TCDD contamination,” and that “The high levels of TCDD contributed almost all of the total toxicity of the samples analyzed, indicating that Agent Orange was the principal source of this dioxin congener.”


These conclusions appear to be questionable because of the presence of other dioxin-like compounds such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and PCBs.  PCDDs, PCDFs, and PCBs must come from sources other than Agent Orange, and these sources may contain TCDD.  Analytical results from this study indicate that these sources may be significant.  For example, the TCDD level in a blood sample from a West Airbase worker (06VNB059) is 150 ppt TEQ while its PCBs level reaches 279 ppt TEQ.  The breast milk sample (06VN201M) contains only 14% TCDD of its 47.2 ppt TEQ (6.76 ppt) while its PCBs level reaches 13.6 ppt TEQ, which exceeds the World Health Organization and Canadian standards.


8.              The Da Nang Report recommends that “Further research, health studies, community education programs and exposure studies are required at Da Nang to verify the extent of the exposure, and to protect populations from further dioxin contamination.  Similar studies should be conducted at other dioxin hot spots in Viet Nam, particular Bien Hoa.  This is consistent with the recommendations of ATSDR [Agency for Toxic Substances and Disease Registry] (1997) for areas where soils levels are ≥  1,000 ppt TEQ.”


We agree that further research, health studies, community education programs and exposure studies should be conducted, but these activities should focus on unknown sources of dioxins such as PCBs and other toxic contaminants such as heavy metals and pesticides.  The contamination at the Da Nang Airbase has been limited in a small area located within a highly restricted area, i.e. a military zone; therefore, its potential risks appear to be significantly less than those from the unknown sources.


It is not clear if the ATSDR guidelines were properly followed for the DDAMP.  In fact, none of the soil/sediment samples collected during a study in 2005 by Hatfield exceeded 275 ppt TEQ.  Even if the dioxin concentrations in soils exceed 1,000 ppt TEQ, a contamination site must be evaluated by a health assessor to determine if it is a public health hazard.  The evaluation must address the following questions:


v             How extensive is the contamination?

v             Is the contamination isolated or widespread?

v             Is the contamination in surface soil or areas easily accessible to children or adults? Is it in areas with no vegetation or in any other areas?

v             At this site, how often (daily, weekly, monthly) and for what length of time (months, years, or lifetimes) would exposures be likely to occur?


The Da Nang Airbase site does not appear to pass this evaluation.


9.              The Da Nang Report recommends that “Fishing activities and lotus harvesting on all natural waterbodies on Da Nang Airbase (Sen Lake, Lake B, and Lake C) should be terminated immediately.... A secure, more permanent fence around the perimeter of the Airbase, particularly at the northern border, is required to prevent access... And alternate livelihoods need to be developed for those individuals who currently earn their living from harvesting fish, lotus and other aquatic organisms and vegetables from Da Nang Airbase.”


We completely agree with these recommendations.


10.            The Da Nang Report recommends that “Individuals sampled for blood and breast milk in this study should be provided with a report on the results of dioxin analyses performed (all donors requested that their results be reported to them,” and that “Detailed human health assessments should be considered in selected areas of Da Nang City to assess the extent of past exposure to herbicides and to ensure no long-term effects of exposure occurs.”


Additional medical examination may be conducted on all individuals who donated the blood and breast milk samples for this study, and probably their off springs, to evaluate potential health effects of the dioxin contamination.  Detailed human health assessments may be considered to assess the extent of the exposure, not only to herbicides (Agent Orange) but also to other toxic contaminants such as PCBs, heavy metals, and pesticides.


11.            The Da Nang Report recommends that “Engineered solutions for hot spots identified at the former Mixing and Loading Area and former Storage Area need to be refined and implemented as soon as possible to prevent further transport of contaminated soil and sediment into the general environment at Da Nang.”


According to the Da Nang Report, “... the major run-off from the Da Nang Airbase hot spots appears to settle in Sen Lake, and likely does not adversely impact the environment outside the northern end of the Airbase;” therefore, engineered solutions for the hot spots at the former Mixing and Loading Area and former Storage Area may not be necessary.  As a precautionary action, however, these areas may be covered or paved by impervious materials to prevent additional run-off from these hot spots.


12.            The Da Nang Report recommends that “A systematic review should be undertaken at Bien Hoa, Phu Cat and other Ranch Hand sites in southern Viet Nam, where Agent Orange was used on site.  In addition, a full investigation needs to be carried out of ARVN bases where Agent Orange spray planes and helicopters were loaded and serviced.”


It is not clear why a systematic review is recommended for the Phu Cat Airbase.  According to the document No. 5612/BCĐ 33-VPBCĐ33 issued by Committee 33 on October 22, 2006, effects of Agent Orange are not observed in the Phu Cat area.


            We hope these findings and comments would help solve the dioxins contamination problem in Vietnam more effectively and efficiently.  We also hope Ford Foundation will expand its financial support to other vital problems such as contamination of surface water and groundwater, especially in rural areas, and management of municipal and industrial wastes.  As long as Vietnam continues to face with these problems, her future appears to be uncertain.


            We thank you for your attention and consideration.  If you have any questions or desire additional information regarding this subject, please do not hesitate to let us know.


Sincerely yours,                       

Text Box:


Text Box:







Quang M. Nguyen, P.E.


Vietnamese American Science and Technology Society




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            Hatfield Consultants