Review of the US Navy's Human Health Risk Assessment of the Naval Air Facility at Atsugi, Japan (2001)

One major problem with NEHC's risk-reduction strategies is the lack of planning for or conducting of evaluations of those strategies. Furthermore, Appendix B of the NEHC draft summary report shows that some risk-reduction strategies have been implemented before peer review or any assessment of their potential effectiveness. That is not appropriate for a risk-management process.

Some of the risk-reduction strategies recommended by NEHC are not supported by the findings in the risk-assessment draft summary report. For example, the recommendation to continue to monitor health-status indicators is vague and should specify which indicators are to be monitored and why, when they are to be monitored, in whom they are to be monitored, and who will monitor them.

The text pertaining to risk reduction is oversimplified. It should discuss how plausible the actions are, whether they can be enforced, and families' compliance with recommendations. For example, recommending that residents close windows and doors when emissions from the incinerator are blowing directly toward NAF Atsugi (Pioneer 2000; p. 93) assumes that base personnel and residents would know when that occurs. The issue of plume-warning properties has not been addressed. Many contaminant concentrations are higher indoors than outdoors, and no comparison has been made between indoor and ambient concentrations specifically when the wind is blowing from the incinerator. Thus, that exposure-mitigation strategy is not supported by the risk analysis and might not be effective in reducing exposures; or it might be effective in reducing exposures to incinerator-related materials but not in reducing overall risks.

Washing of hands, forearms, face, tools, toys, and so on, after outdoor activities that result in direct contact with soil or dust is good advice and practice, but risk reduction by such measures has not been determined (Pioneer 2000; p. 93). NEHC has not adequately determined who is at risk; once that has been done, the risk-reduction strategy should be focused where it might be most effective. For example, if young children are most at risk, the strategy should be focused on reducing exposure of and risk to young children.

The subcommittee believes that NEHC should consider other strategies for reducing the risks to families living at NAF Atsugi. One expensive but effective strategy might be to build new residential and child-care facilities on parts of NAF Atsugi that are farther from the incinerator complex (for example, at the recreational field near the clinic). The feasibility of that approach might depend on the age of the existing housing at NAF Atsugi, but it might dramatically lower the exposure of families to incinerator emissions.

It appears that the Navy is interested principally in the health effects of incinerator emissions on American personnel. However, although some of the contractor documents (such as Pioneer 2000) include anecdotal reports of respiratory effects (possibly due to exposure to incinerator emissions), health effects actually observed are not mentioned, nor is surveillance for such health effects or whether concerns have been raised about particular health effects. The subcommittee is aware of studies conducted by Laurel A. May and David Sack at NAF Atsugi and focusing on adverse pregnancy outcomes (including spontaneous abortions) and children's health. Appendix B of the NEHC draft summary report mentions the existence of surveillance studies but their design and results should be mentioned in the main section of the NEHC report. The subcommittee recognizes that such surveillance is not a part of traditional risk assessments but believes that it could provide useful, complementary information.

Health surveillance of personnel and their families residing at NAF Atsugi is useful for assessing all but chronic effects with latent periods in excess of the period of residence. Because of the rather small

number of people at Atsugi, epidemiologic methods could attribute only large increases in incidence above background to living at NAF Atsugi. Risk assessment is capable of assessing lifetime risk at low levels. But surveillance of outcomes amenable to this approach can eliminate many of the uncertainties inherent in risk assessment. Therefore, the subcommittee recommends that NEHC use both approaches, especially where data are already available.

Surveillance can be either active or passive. Active surveillance is desirable and most likely to ascertain new cases of disease or episodes of illness, but passive strategies built on the medical-care infrastructure might be more readily implemented. A single medical center serves the population residing at NAF Atsugi, so good medical records on the population should be available for use in a health-surveillance program. Use of sentinel cases of disease might prove useful for health surveillance. An evaluation of the health risks that looks at acute, possibly reversible effects, as well as potential chronic effects, could also be useful. Appendix B of the NEHC draft summary report lists some of the health concerns raised by stakeholders at NAF Atsugi. Stakeholders' concerns should be taken into account when designing surveillance programs.

NEHC should consider studying the potential health effects of peak contaminant concentrations (for example, correlating contaminant concentrations with anecdotal subjective reports) to assess irritation and other short-term reversible but unpleasant effects. Short-term unpleasant effects—such as nasal and eye irritation, coughing, and odors—are unlikely to be documented in medical records, but surveys could potentially be used to assess them and should be taken on days with varied contaminant concentrations.

Surveillance data could be used in conjunction with risk assessment, perhaps focusing the risk assessment on end points of particular interest. A surveillance program could also be helpful in risk-management decisions and in risk communication.

Little indoor-dust monitoring was conducted, and its purpose is not apparent in the NEHC draft summary report. In a Radian report (1998a; p. 4-19), the purpose of monitoring dust was stated this way:

In order to evaluate the potential for an ingestion route of exposure due to deposited or “trackedin” dust, surface sampling will be performed once at each of the seven indoor sites whose air will be tested.

The NEHC draft summary report, however, does not connect the observed results to that stated purpose.

Discussion of the dust monitoring in the NEHC draft summary report could be misleading. After noting that indoor-dust samples contained only trace components that could be associated with combustion products, NEHC implies (p. 27) that the lack of combustion-associated particles in the dust samples was due to the sampling method:

Following the assumption that combustion products may be found in particles greater than 5 µm two PM₁₀ filter samples (one indoor and another outdoor) were also subjected to a microscopical analysis.

However, the dust samples were collected by a vacuum method (Micro-Sciences 1999; p. 12) that samples larger particles (greater than 5 µm), so the composition of smaller particles, not larger ones, might be at issue. If the quoted passage was meant to indicate that combustion products can be found in particles smaller than 5 µm (that is, was written incorrectly)—and an appreciable fraction of the PM₁₀ samples would be of such smaller particles—then a method that collected the particles of the desired sizes should have been used.