133 Molesworth Street
PO Box 5013
Wellington 6140
New Zealand
T+64 4 496 2000
30 April 2026
Alisha Riley
By email: [FYI request #34286 email]
Ref:
H2026080738
Tēnā koe Alisha
Response to your request for official information
Thank you for your request under the Official Information Act 1982 (the Act) to the Ministry of
Health – Manatū Hauora (the Ministry) on 29 March 2026 for information relating to data models
and methodology for the November and December 2024 public health publications. You
requested:
I am currently doing some research into public health methodology and toxicology, and I
am trying to understand the scientific workings behind the Public Health Agency’s recent
NZBORA analysis (specifical y the Memorandum to the Director-General dated 29
November 2024).
I was reading Paragraph 25 of the Memo, which mentions that the Office of the Chief
Science Advisor (OCSA) reviewed the recent US NTP Monograph and the 2024
Cochrane Review, and concluded that they "do not change the overal conclusions
reached". I am struggling to reconcile some of the math and toxicology in my own
research, so I was hoping to request the internal workings and models the OCSA used so
I can fol ow along and better understand their assessment.
I am requesting the fol owing information and internal documentation:
(Scope Limitation to prevent substantial col ation:
To ensure this request is highly targeted and does not require substantial col ation or
research under Section 18(f) of the OIA, I am happy to limit the scope of any searches for
"emails," "meeting minutes," or "correspondence" to the 12-month period between
January 1, 2024, and December 31, 2024. Furthermore, for any requested "memos,"
"models," or "evaluations," providing the final approved versions rather than draft
iterations is perfectly fine.)
Part 1: The 2024 Cochrane Review
I was reading the 2024 Cochrane Review, and it noted a 40% fluorosis prevalence, a
marginal benefit of only 0 to 1/4 of a tooth for primary dentition, and didn't find eligible
studies for adult benefit. I'm trying to figure out how to weight a fraction of a tooth against
a 40% prevalence rate mathematical y in a public health cost-benefit model.
1. Could I please request any internal memos, meeting notes, or emails from the OCSA
discussing this Cochrane review?
2. I would also need to see any mathematical models, statistical analyses, or documents
the OCSA produced that show how they factored these specific Cochrane findings—
specifical y the 1/4 tooth benefit versus the 40% fluorosis rate—into their conclusion that
the safety and proportionality of the mandate remained unchanged.
Part 2: US National Toxicology Program (NTP) Monograph
For the August 2024 US NTP Monograph, I'm trying to learn how standard toxicological
safety margins are applied to population-wide policies.
3. Could I please request any literature reviews or toxicological evaluations the OCSA did
specifical y assessing the neurodevelopmental hazards identified in the NTP report?
4. Could I also request any specific calculations the OCSA performed to establish the
safety margins (such as standard 10x or 100x uncertainty factors) for vulnerable
demographics like infants and pregnant women in light of the NTP's findings?
Part 3: Genetic Vulnerability, Metabolic Disability, and Demographic Dosing
I have also been looking into population subgroups with genetic vulnerabilities and
metabolic disabilities, but I can't seem to find the standard public health models outlining
the physiological dose burdens for these specific groups.
5. Could I please request any OCSA risk assessments, literature reviews, or internal
communications that look at how systemic fluoride interacts with the MAOA-L genetic
phenotype, as wel as specific polymorphisms clinical y recognized as resulting in
metabolic disability (such as the VDR Bsm, MTHFR, and CBS C699T variants)?
6. Additional y, could I request the model ing or documentation the OCSA used to
calculate the cumulative dose burden (mg/kg of body weight) for exclusively formula-fed
infants? I'm particularly interested in how the OCSA calculations accounted for the
statistical y higher rates of formula feeding within Māori and Pacific populations.
Part 4: 2009 Oral Health Survey
Final y, I noticed the 2009 New Zealand Oral Health Survey didn't track fluorosis or
structural enamel defects for children under 8 or adults over 30. Since this survey is used
as a baseline for safety, I'm a bit confused about how to account for those missing age
brackets.
7. Could I please request any scientific evaluations or memos produced by the OCSA that
discuss how they addressed these missing diagnostic data points when confirming the
safety of the policy?
Part 5: Biological Mechanism and Classification of Dental Fluorosis
I was also reading the Ministry's recent publication, Community Water Fluoridation: An
evidence review (published December 2024 by the Ministry of Health). On page 3, it
summarises the OPMCSA's conclusion that dental fluorosis is a "tooth enamel defect" and
states that at NZ levels it is "general y mild (i.e., of no health concern and little-to-no
cosmetic concern)".
However, in my pathology and histology readings, dental fluorosis is described as an
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"inside-out" systemic condition resulting from the disruption of ameloblasts during tooth
formation, leading to subsurface hypomineralisation and increased dentin porosity, rather
than just a surface-level enamel stain. I am trying to figure out how to classify this in a
physiological harm model.
8. Could I please request any histological reviews, biological models, or internal
evaluations the Ministry of Health (including the OCSA and Public Health Agency) relied
upon to medical y classify fluorosis strictly as a surface-level "enamel defect" rather than a
systemic structural impairment involving subsurface and dentin porosity?
9. Could I also request any specific risk assessment frameworks, clinical rubrics, or
memos the Ministry of Health uses to mathematical y draw the line between a "cosmetic
concern" and a "health/structural concern" when calculating the overal harm vs. benefit
for public health directives?
10. As the Ministry's 2024 review adopted the OPMCSA's specific conclusions, could I
please request any correspondence, emails, or meeting minutes between the Ministry of
Health and the OPMCSA discussing this biological classification of fluorosis and how to
weight it in a safety assessment?
Part 6: Exclusion of Benchmark Dose (BMD) Modeling
I was also reviewing the methodology in "Appendix 3: Exclusion table for
neurodevelopmental outcomes" of the December 2024 Evidence Review. I noticed that
several landmark toxicological studies (such as Grandjean et al. 2022 and Hirzy et al.
2016) were entirely excluded from the safety analysis, with the stated reason being:
"Wrong outcome (benchmark dose analysis)".
In my environmental toxicology coursework, Benchmark Dose (BMD) modeling is taught
as the international gold standard for establishing safe exposure thresholds and Point of
Departure (POD) metrics for public health regulations. I am confused as to why BMD is
classified as the "wrong outcome" for a chemical safety review in New Zealand.
11. Could I please request any internal OCSA or Ministry of Health methodological
guidelines, memos, or correspondence that dictate why Benchmark Dose Analysis is
classified as an invalid or "wrong" outcome when assessing the safety of community water
fluoridation?
12. Since BMD modeling was excluded, could I please request the specific alternative
mathematical models and toxicological frameworks the OCSA or Ministry of Health relied
upon to accurately establish the Point of Departure (POD) and safe reference dose for
neurodevelopmental toxicity in the December 2024 review?
Information related to questions 2, 3 and 11 of your request is publicly available in Appendix 5 –
Community water fluoridation: Additional information on recent publications at the fol owing link:
www.health.govt.nz/information-releases/director-general-of-health-consideration-of-community-
water-fluoridation-under-the-new-zealand-bil Therefore, section 18(d) of the Act applies to
these parts of your request.
The Ministry has undergone a search of its records, and no information has been identified
within scope of questions 1, 4-10 and 12. As such, these parts of your request are refused
under section 18(g)(i) of the Act as the information requested is not held by the Ministry and
there are no grounds for believing this information is connected more closely with the functions
of another agency subject to the Act.
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If you wish to discuss any aspect of your request with us, including this decision, please feel
free to contact the OIA Services Team on: [email address].
Under section 28(3) of the Act, you have the right to ask the Ombudsman to review any
decisions made under this request. The Ombudsman may be contacted by email at:
[email address] or by cal ing 0800 802 602.
Please note that this response, with your personal details removed, may be published on the
Ministry website at: www.health.govt.nz/about-ministry/information-releases/responses-official-
information-act-requests
Nāku noa, nā
Barbara Burt
Acting Group Manager, Public Health Strategy and Policy
Public Health Agency and Mental Health Group
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