1

Filed 3/23/23

CERTIFIED FOR PUBLICATION

IN THE COURT OF APPEAL OF THE STATE OF CALIFORNIA

THIRD APPELLATE DISTRICT

(Sacramento)

----

CALIFORNIA MANUFACTURERS &

TECHNOLOGY ASSOCIATION,

Plaintiff and Appellant,

v.

OFFICE OF ENVIRONMENTAL HEALTH 

HAZARD ASSESSMENT et al.,

Defendants and Respondents.

C093351

(Super. Ct. No. 34-2015-

80002120-CU-WM-GDS)

APPEAL from a judgment of the Superior Court of Sacramento County, Laurie M. 

Earl, Judge. Affirmed.

Downey Brand, Jay-Allen Eisen, Annie S. Amaral, and Alexandra K. LaFountain

for Plaintiff and Appellant.

Beveridge & Diamond and Kaitlyn D. Shannon for American Chemistry Council 

as Amicus Curiae on behalf of Plaintiff and Appellant

Rob Bonta, Attorney General, Edward H. Ochoa, Senior Assistant Attorney 

General, Laura J. Zuckerman, and Elizabeth Song, Deputy Attorneys General, for 

Defendants and Respondents.
2

“Every resident of California has the right to pure and safe drinking water.” 

(Health & Saf. Code, § 116270, subd. (a).)1 To protect the quality of drinking water in 

California, under the California Safe Drinking Water Act (§ 116270 et seq.), defendant 

Office of Environmental Health Hazard Assessment (OEHHA) is charged with 

conducting a risk assessment for contaminants in drinking water. This process includes

setting a “public health goal” (PHG) for such contaminants, an aspirational “estimate of 

the level of the contaminant in drinking water that is not anticipated to cause or 

contribute to adverse health effects, or that does not pose any significant risk to health.” 

(§ 116365, subd. (c)(1).) After OEHHA sets its PHG, the State Water Resources Control 

Board sets a maximum contamination level for that contaminant to be included in the

primary drinking water standard.

At issue here is the 2015 PHG OEHHA set for the contaminant perchlorate, a 

chemical found in rocket fuel. After OEHHA set the PHG for perchlorate at 1 part per 

billion (ppb), plaintiff California Manufacturers & Technology Association (CMTA) 

filed a petition for a writ of mandate ordering OEHHA to withdraw the PHG. The trial 

court denied the petition.

On appeal, CMTA raises two primary contentions. It asserts (1) OEHHA violated 

the statutory mandate in arriving at the PHG. Specifically, for an “acutely toxic 

substance” such as perchlorate, the statute requires the PHG “shall be set at the level at 

which no known or anticipated adverse effects on health occur, with an adequate margin 

of safety.” (§ 116365, subd. (c)(1)(A).) CMTA asserts OEHHA violated this 

requirement by setting the PHG at a level where a nonadverse effect on health occurs. 

CMTA also asserts (2) the PHG is void based on the common law conflict of interest 

doctrine because its author, Dr. Craig Steinmaus, had a conflict of interest. Steinmaus

1 Undesignated statutory references are to the Health and Safety Code.
3

had previously published three studies on perchlorate, and, according to CMTA, in 

determining the PHG, he would at the least be tempted to arrive at a result that would 

protect and burnish his professional reputation.

We conclude OEHHA complied with the statutory requirements under section 

116365, subdivision (c)(1)(A). We further conclude the common law conflict of interest 

doctrine does not apply here. We affirm.

BACKGROUND

The California Safe Drinking Water Act

The Legislature enacted the California Safe Drinking Water Act, among other 

things, “to ensure that the water delivered by public water systems of this state shall at all 

times be pure, wholesome, and potable.” (§ 116270, subd. (e).) “To effectuate this 

purpose, the [California Safe Drinking Water] Act articulates a state policy to ‘reduce to 

the lowest level feasible all concentrations of toxic chemicals that, when present in 

drinking water, may cause cancer, birth defects, and other chronic diseases.’ ” 

(California Manufacturers & Technology Assn. v. State Water Resources Control Bd.

(2021) 64 Cal.App.5th 266, 272 (California Manufacturers), quoting § 116270, 

subd. (d).) “The [California Safe Drinking Water] Act also expresses an intent to 

establish a safe drinking water program ‘that is more protective of public health than the 

minimum federal requirements.’ ” (California Manufacturers, at p. 272, quoting 

§ 116270, subd. (f).)

The California Safe Drinking Water Act provides for a two-step process for setting 

drinking water contaminant standards. First, OEHHA must “prepare and publish an 

assessment of the risks to public health posed by each contaminant for which the state 

board proposes a primary drinking water standard.” (§ 116365, subd. (c)(1).) This risk 

assessment must include a PHG, which is “an estimate of the level of the contaminant in 

drinking water that is not anticipated to cause or contribute to adverse health effects, or 

that does not pose any significant risk to health.” (Ibid.) Furthermore, a specific standard 
4

applies if the subject contaminant is an “acutely toxic substance.” (§ 116365, 

subd. (c)(1)(A).) “If the contaminant is an acutely toxic substance, the public health goal 

shall be set at the level at which no known or anticipated adverse effects on health occur, 

with an adequate margin of safety.” (Ibid.)

To the extent information is available, the PHG shall take into account, among 

other things, “[a]dverse health effects the contaminant has on members of subgroups that 

comprise a meaningful portion of the general population, including, but not limited to, 

infants, children, [and] pregnant women”; the “relationship between exposure to the 

contaminant and increased body burden and the degree to which increased body burden 

levels alter physiological function or structure in a manner that may significantly increase 

the risk of illness”; and the “additive effect of exposure to the contaminant in media other 

than drinking water, including, but not limited to, exposures to the contaminant in food, 

and in ambient and indoor air, and the degree to which these exposures may contribute to 

the overall body burden of the contaminant.” (§ 116365, subd. (c)(1)(C)(ii)-(iv).)

PHG’s “are aspirational rather than mandatory or enforceable.” (California 

Manufacturers, supra, 64 Cal.App.5th at pp. 272-273.) OEHHA is required to review 

each PHG “at least once every five years unless the office determines . . . that there has 

not been a detection of the corresponding contaminant in the preceding five years.” 

(§ 116365, subd. (e)(1).)

As for the second step in the process, after OEHHA sets the PHG for a

contaminant and completes its risk assessment, the State Water Resources Control Board 

sets a maximum contaminant level (MCL) for that contaminant. The MCL must be set

“ ‘at a level that is as close as feasible to the corresponding [PHG][,] placing primary 

emphasis on the protection of public health, and that, to the extent technologically and 

economically feasible’ avoids any significant risk to public health.” (California 

Manufacturers, supra, 64 Cal.App.5th at pp. 280-281, quoting § 116365, subd. (a).) 

“Unlike MCL[’]s, which are the product of several statutorily enumerated considerations
5

. . . , [PHG’s] are based exclusively on public health considerations.” (California 

Manufacturers, at p. 272, citing § 116365, subd. (c)(1).)

Perchlorate

Perchlorate is a chemical compound used in rocket fuel, slurry explosives, road 

flares, and air bag inflation systems. Perchlorate can occur in nature and, through 

rainfall, circulate at low levels throughout the environment. Perchlorate is also released 

into the environment by human activity. For example, perchlorate can leach into soil and 

aquifers through the disposal of rocket fuel. Perchlorate can remain in the ground and in 

surface waters for decades. Since 1997, agencies have reported the presence of 

perchlorate “in thousands of drinking water sources and wells throughout” California.

When ingested, perchlorate can have the effect in humans of inhibiting the uptake 

of iodide in the thyroid gland. This is known as iodide uptake inhibition (IUI). Iodine is 

a component of two hormones produced by the thyroid. Transfer of iodide into the 

thyroid gland is “an essential step in the synthesis of” these hormones. Thyroid 

hormones are necessary to a variety of basic human physiological functions, including 

“regulat[ing] the body’s metabolism and physical growth.” Inhibition of iodide transfer 

into the thyroid can result in iodide deficiency and, consequently, reduction in the 

synthesis of the hormones, a condition known as hypothyroidism. According to the 

National Academy of Sciences, hypothyroidism is the first adverse effect on the 

“continuum of possible health effects of perchlorate exposure.”2 If thyroid hormone 

production falls substantially in a healthy adult, adverse health effects may result. Any 

“decrease is potentially more likely to have adverse effects in sensitive populations 

2 The National Academy of Sciences “is a private, nonprofit, self-perpetuating 

society of distinguished scholars engaged in scientific and engineering research, 

dedicated to the furtherance of science and technology and to their use for the general 

welfare.”
6

(people with thyroid disorders, pregnant women, fetuses, and infants) . . . .” Ordinarily, 

the body maintains concentrations of thyroid hormones within limits through the body’s 

own “feedback control mechanisms.” However, “even small decreases in thyroid 

hormone levels may be associated with significant adverse effects, including altered 

cognitive development in children and increased cardiovascular risk factors in adults.”

OEHHA’s 2004 PHG for Perchlorate

In 2002, a court ordered OEHHA to submit a revised PHG for perchlorate for 

public comment and to subject its PHG to peer review. Each of three peer reviewers

agreed with the identification of particularly sensitive subpopulations, specifically 

pregnant women, fetuses, and people with compromised thyroid function, arriving at a 

PHG sufficient to protect those subpopulations. 

The first peer reviewer noted “the potential impact of trace levels of perchlorate 

may be nil.” He did not recommend a particular PHG. He noted OEHHA determined

that “iodine uptake per se is an adverse effect and, therefore, suitable for use in risk 

assessment and the determination of PHG.” He further concluded the “critical effect,” 

which the reviewer equated to the “first adverse effect,” of perchlorate exposure was “not 

inhibition of iodine entry, but” rather a decrease in thyroid hormone during pregnancy.

The second reviewer noted that “the calculation of the PHG in the OEHHA 

document is based on an effect that is not a direct adverse health event, but rather a 

precursor to an adverse health event.” The second reviewer opined that a PHG of 2 ppb

“seems reasonably justified.”3 

The third peer reviewer recommended a PHG of 18.6 micrograms per liter.

In 2004, OEHHA announced its PHG of 6 ppb for perchlorate.

3 While the peer reviewers at the time were not identified, OEHHA stipulated the 

second peer reviewer in 2002 was Dr. Steinmaus.
7

OEHHA’s 2015 PHG for Perchlorate

OEHHA began the process of reviewing its PHG for perchlorate in 2008. It issued 

a draft PHG in January 2011, proposing a PHG of 1 ppb for perchlorate in drinking 

water. Dr. Steinmaus authored the draft, which was reviewed by five OEHHA scientists.

The draft stated the “current OEHHA PHG of 6 ppb was set in 2004. The 

methods used to develop the proposed PHG described here are similar to those used to 

develop the 2004 PHG in that both are based on the same thyroidal [IUI] data . . . .” The 

draft further stated the “major difference between the 2004 PHG calculations and the 

present proposal is that the 2004 PHG document focused on pregnant women and their 

fetuses as the primary susceptible population, whereas the proposed PHG focuses on 

infants.” The draft noted new data indicated drinking water intakes per body weight were 

higher in infants than previously thought, resulting in the likelihood that infants had 

greater perchlorate exposure per body weight from drinking water than estimated in 

2004.

The draft further stated: “[T]he identification of the point of departure, prevention 

of thyroidal iodide uptake, is a health-protective decision since it is intended to prevent 

the very first step of a process that leads to thyroid hormone imbalance and other related 

adverse health effects.” The draft continued: “The purpose of the proposed perchlorate 

PHG is to help prevent any perchlorate-related reduction in thyroid iodine uptake that 

might lead to decreases in thyroid hormone production. As discussed above, recent 

evidence suggests that even small decreases in thyroid hormone levels may be associated 

with significant adverse effects, including altered cognitive development in children and 

increased cardiovascular risk factors in adults. Importantly, these changes have been 

seen at thyroid hormone levels that are within what have been traditionally defined as 

normal reference ranges, and have occurred in people without any other evidence of overt 

thyroid disease. These findings suggest that any change in thyroid hormone levels, no 

matter how small, may be associated with at least some increased risk of thyroid-related 
8

adverse outcomes.” Among other sources, the draft relied on studies Dr. Steinmaus 

coauthored in 2007 and 2010.

Three outside scientists reviewed the draft. One reviewer noted the most 

vulnerable subpopulation identified by the PHG was infants, and further noted that, given 

“the small thyroidal reserves of neonates and the possible need for an uninterrupted 

supply of iodine, this seems to be a reasonable change from the previous PHG’s focus on 

pregnant women, whose fetuses may be protected by larger maternal stores.” She further 

stated that, given “how little we know about the sensitivity of infants, particularly 

neonates, to thyroid hormone disruption or about iodine intake among pregnant women 

and breastfed infants it seems reasonable to be cautious about exposing them to thyroidhormone disrupting agents.” She stated it was “appropriate and reasonable” to consider 

the decrease in iodide uptake, and that “[u]sing inhibition of iodide uptake as the critical 

event is appropriate since this is the first step in perchlorate toxicity, and any other effects 

would follow subsequently.” She concluded that, until more information was gathered, 

“a drinking water concentration of 1 ppb is likely protective to the population.” Another 

reviewer concurred infants were more sensitive to the effects of perchlorate. He 

recommended a PHG of 2 ppb.

OEHHA circulated a second draft PHG in December 2012. The second draft 

adhered to the proposed 1 ppb PHG. OEHHA received several letters offering feedback, 

much of it negative.

OEHHA issued the final PHG for perchlorate in February 2015. Dr. Steinmaus 

was the author. There were eight OEHHA reviewers of the final PHG. Consistent with 

the draft PHG’s, OEHHA set the PHG at 1 ppb. As with the drafts, “OEHHA used 

decreased uptake of iodide by the thyroid gland as the key biochemical event for 

assessing the risks due to perchlorate toxicity.” “OEHHA considers effects on thyroid 

hormone production and subsequent changes to be adverse. [IUI] is the key event that 

leads to other possible effects from perchlorate exposure. Prevention of [IUI] prevents 
9

progression to the adverse health effects of perchlorate.” The PHG noted the National 

Academy of Sciences “deemed ‘inhibition of iodide uptake by the thyroid as the basis of 

the perchlorate risk assessment to be the most health-protective and scientifically valid 

approach.’ OEHHA agrees with this approach and used it in developing its original 2004 

PHG for perchlorate.” Thus, the PHG stated that the value of 1 ppb “is intended to help 

prevent any perchlorate-related decrease in iodide uptake by the thyroid that could lead to 

decreased thyroid hormone production and that could disrupt the important functions of 

this hormone.”

CMTA’s Writ Petition

Pursuant to Code of Civil Procedure section 1085, CMTA filed a petition for a 

writ of mandate ordering OEHHA “to withdraw the current revised PHG for perchlorate 

and to identify a new revised PHG for perchlorate in compliance with legal 

requirements.”

CMTA asserted section 116365 requires that the PHG “shall be set at the level at 

which no known or anticipated adverse effects on health occur, with an adequate margin 

of safety.” (§ 116365, subd. (c)(1)(A).) According to CMTA, in its determination of the 

PHG, OEHHA violated this statutory mandate.

CMTA also asserted that, as both “principal author of the PHG technical support 

document on which the PHG is based, and the author of the key studies on which the 

technical support document relies,” Dr. Steinmaus had a conflict of interest which

“should have resulted in his recusal . . . .” According to CMTA, “OEHHA’s decision to 

have Dr. Steinmaus conduct the required assessment and author the corresponding report 

created a conflict of interest which compromised the PHG process and violated 

OEHHA’s obligations under both the Health and Safety Code and common law conflict 

of interest principles.”

The trial court denied CMTA’s writ petition and entered judgment in OEHHA’s 

favor.
10

DISCUSSION

I

Compliance with Section 116365 in Setting the PHG

A. Standard of Review

“Code of Civil Procedure section 1085 permits judicial review of ministerial 

duties as well as quasi-legislative and legislative acts.” (County of Los Angeles v. City of 

Los Angeles (2013) 214 Cal.App.4th 643, 653.) Here, we address OEHHA’s 

interpretation of a statute, specifically section 116365, subdivision (c)(1). In reviewing 

the trial court’s denial of a writ of mandate pursuant to Code of Civil Procedure section 

1085, “[w]here the facts are undisputed and the issue is one of statutory interpretation, we 

review the trial court’s ruling de novo.” (Asian Americans Advancing Justice—Los 

Angeles v. Padilla (2019) 41 Cal.App.5th 850, 863, fn. omitted; accord, Lopez v. 

Ledesma (2022) 12 Cal.5th 848, 857 [generally appellate court reviews questions of 

statutory interpretation de novo].)

However, “ ‘[i]n determining whether an agency has incorrectly interpreted the 

statute it purports to implement, a court gives weight to the agency’s construction.’

[Citation.] ‘How much weight to accord an agency’s construction is “situational,” and 

greater weight may be appropriate when an agency has a “ ‘comparative interpretative 

advantage over the courts,’ ” as when “ ‘the legal text to be interpreted is technical, 

obscure, complex, open-ended, or entwined with issues of fact, policy, and discretion.’ ”

[Citation.] Moreover, a court may find that “the Legislature has delegated the task of 

interpreting or elaborating on a statute to an administrative agency,” for example, when 

the Legislature “employs open-ended statutory language that an agency is authorized to 

apply or ‘when an issue of interpretation is heavily freighted with policy choices which 

the agency is empowered to make.’ ” [Citations.] In other words, the delegation of 

legislative authority to an administrative agency sometimes “includes the power to 

elaborate the meaning of key statutory terms.” [Citation.] Nevertheless, the proper 
11

interpretation of a statute is ultimately the court’s responsibility.’ ” (California 

Manufacturers, supra, 64 Cal.App.5th at pp. 279-280.)

B. Principles of Statutory Interpretation

“ ‘ “Under settled canons of statutory construction, in construing a statute we 

ascertain the Legislature’s intent in order to effectuate the law’s purpose. [Citation.] We 

must look to the statute’s words and give them their usual and ordinary meaning.

[Citation.] The statute’s plain meaning controls the court’s interpretation unless its words 

are ambiguous.” [Citations.] If the words in the statute do not, by themselves, provide a 

reliable indicator of legislative intent, “[s]tatutory ambiguities often may be resolved by 

examining the context in which the language appears and adopting the construction 

which best serves to harmonize the statute internally and with related statutes. 

[Citation.]” [Citation.] . . . If the statute is ambiguous, we may consider a variety of 

extrinsic aids, including legislative history, the statute’s purpose, and public policy.’ ” 

(People v. Lucero (2019) 41 Cal.App.5th 370, 394-395; accord, Union of Medical 

Marijuana Patients, Inc. v. City of San Diego (2019) 7 Cal.5th 1171, 1183-1184.)

C. CMTA’s Contentions

As stated, in setting the PHG, “OEHHA used decreased uptake of iodide by the 

thyroid gland,” or IUI, “as the key biochemical event for assessing the risks due to 

perchlorate toxicity.” CMTA maintains this violated the statutory mandate because the 

PHG must be set at a level to prevent adverse health effects, not nonadverse health 

effects, and IUI is not an adverse health effect.4 

CMTA notes, correctly, that the National Academy of Sciences has explicitly 

stated IUI is a “nonadverse effect rather than an adverse effect.” That body nonetheless 

recommended use of IUI “as the point of departure for the perchlorate risk assessment” 

4 The California Safe Drinking Water Act does not specifically define the terms 

“adverse” or “adverse effects on health.” (See § 116275.)
12

because using “a nonadverse effect that is upstream of the adverse effects is a

conservative, health-protective approach to the perchlorate risk assessment.” CMTA also 

cites OEHHA’s “Questions and Answers” published in connection with the 2004 PHG. 

In it, OEHHA noted: “The perchlorate health effect of primary concern is the reduction 

of the uptake of iodide, an essential nutrient, by the thyroid gland . . . . While not harmful 

by itself, inadequate iodide uptake may lead to the harmful disruption of proper thyroid 

function.” (Italics added.) In the same document, OEHHA further noted that its 2004 

perchlorate PHG, like the current PHG and like the National Academy of Sciences 

approach, “focused on the reduction of iodide uptake as the critical health effect.” 

Additionally, OEHHA acknowledged in the 2015 PHG that IUI was “the key event that 

leads to other possible effects from perchlorate exposure” and that prevention of IUI 

“prevents progression to the adverse health effects of perchlorate.” Similarly, in its 2015 

publication responding to public comments, OEHHA stated it treated IUI “as it would an 

adverse event because it is in the direct causal pathway between perchlorate exposure and 

several important adverse events.” (Italics added.)

Thus, according to CMTA, IUI is not an adverse health effect, and OEHHA has 

explicitly acknowledged as much. By regulating to prevent it, OEHHA violated section 

116365, expanding the scope of that section and exceeding the authority granted to it 

thereunder.

D. Analysis

There is no dispute among the parties that perchlorate is an acutely toxic substance

within the meaning of section 116365, subdivision (c)(1)(A). Accepting the premise that 

perchlorate is indeed an acutely toxic substance, we consider whether OEHHA acted 

within its authority in identifying IUI as the effect on health to prevent such that, in 

avoiding it, the PHG would be “set at the level at which no known or anticipated adverse 

effects on health occur, with an adequate margin of safety.” (§ 116365, subd. (c)(1)(A).) 

In other words, as a corollary, we essentially consider whether IUI gives rise to a “known 
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or anticipated adverse effect[ ] on health.” (Ibid.) We conclude that, in setting the PHG, 

OEHHA properly identified IUI as a “known or anticipated adverse effect[ ] on health,” 

and therefore it complied with section 116365, subdivision (c)(1)(A) in setting the PHG.

If the statute specifically required OEHHA to set the PHG at a level at which no 

known adverse effects on health occur, we might find CMTA’s position—that IUI is not 

an adverse effect on health and therefore should not be used in setting the PHG—to be 

more persuasive. However, the statute also requires OEHHA to set the PHG at a level “at 

which no . . . anticipated adverse effects on health occur, with an adequate margin of 

safety.” (§ 116365, subd. (c)(1)(A).) In other words, the statute requires OEHHA to set 

the PHG at a level that will prevent the occurrence of anticipated adverse health effects. 

CMTA accuses OEHHA of effectively reading the word “adverse” out of the statute. 

However, we conclude CMTA’s interpretation essentially reads the words “or 

anticipated” out of the statute.

Based on our reading of the plain language of the statute, we conclude OEHHA 

acted within its statutory authority in concluding that the onset of IUI results in 

“anticipated adverse effects on health,” and that therefore the PHG must be set at a level 

so as to prevent IUI. (§ 116365, subd. (c)(1)(A).) The California Safe Drinking Water 

Act does not define “anticipated” in its definitions (§ 116275), and we find it helpful to 

resort to dictionary definitions for this term and others (see Wasatch Property 

Management v. Degrate (2005) 35 Cal.4th 1111, 1121-1122 [when ascertaining ordinary, 

usual meaning of a word, courts appropriately refer to dictionary definition]). Dictionary 

definitions of “anticipate” include: “to give advance thought, discussion, or treatment 

to,” “to meet (an obligation) before a due date,” “to foresee and deal with in advance,” 

“to act before (another) often so as to check or counter,” and “to look forward to as 

certain.” (Merriam-Webster’s Collegiate Dict. (11th ed. 2006) p. 54.) Synonyms include 

“foresee” and “prevent.” (Ibid., capitalization omitted.) Employing these definitions, 

OEHHA could conclude, for example, the onset of IUI resulted in foreseeable adverse 
14

health effects to be dealt with in advance. Thus, in setting the PHG to avoid IUI, 

OEHHA set the PHG “at the level at which no known or anticipated adverse effects on 

health occur, with an adequate margin of safety.” (§ 116365, subd. (c)(1)(A), italics 

added.)

The record fully supports the conclusion that, with the onset of IUI, adverse 

effects on health are anticipated. OEHHA stated in the 2015 PHG that IUI was “the key 

event that leads to other possible effects from perchlorate exposure” and that prevention 

of IUI “prevents progression to the adverse health effects of perchlorate.” In its 2015 

publication responding to public comments, OEHHA stated IUI “is in the direct causal 

pathway between perchlorate exposure and several important adverse events.” OEHHA 

stated the use of IUI in establishing the PHG was a “health-protective decision since it is 

intended to prevent the very first step of a process that leads to thyroid hormone 

imbalance and other related adverse health effects.” It further stated, “OEHHA considers 

effects on thyroid hormone production and subsequent changes to be adverse. [IUI] is 

the key event that leads to other possible effects from perchlorate exposure. Prevention 

of [IUI] prevents progression to the adverse health effects of perchlorate.”

We reach this conclusion notwithstanding the fact, as stated by the National 

Academy of Sciences, that “outcomes at the end of the continuum” of health effects 

caused by perchlorate exposure may not be “inevitable consequences” of that exposure. 

Based on our interpretation of the statutory language, OEHHA could set the PHG at a 

level where there exist foreseeable, if not inevitable, adverse health effects. Indeed, if 

there were a condition, such as IUI, the onset of which always and inevitably resulted in 

adverse health effects, it is not difficult to imagine characterizing such condition itself as 

a known adverse effect on health.

Further reinforcing our determination is the statutory language stating that the 

PHG shall be set at the specified level, “with an adequate margin of safety.” (§ 116365, 

subd. (c)(1)(A).) We conclude this language builds into the PHG determination a degree 
15

of latitude, particularly where the precise point at which known adverse effects on health 

may occur, or the precise volume of exposure to a contaminant that will cause such 

effects, is uncertain. In other words, we read this qualifier as building into the process 

reasonable room—a margin—to account for uncertainty so as to ensure public health.

In its grammatical and lexical interpretation, CMTA asserts the phrase, “with an 

adequate margin of safety” modifies the sentence’s main subject, the level at which the 

PHG shall be set. CMTA further asserts that the words “level” and “margin” are metrics, 

and thus the phrase effectively calls for the further refining of a numerical value of the 

PHG. Essentially, CMTA’s reading of the statute would call for the setting of the initial 

PHG at a specified value and then adjusting that numerical value by the additional 

numerical value of a margin of safety.

We read the phrase “with an adequate margin of safety” in a more general way. 

We read this language as providing latitude for OEHHA to ensure public health, 

particularly where the level at which known adverse effects on health may arise, or the 

amount of exposure that will cause such effects, is not entirely clear. CMTA is correct 

that one definition of the word “margin” is a “spare amount or measure or degree allowed 

or given for contingencies or special situations.” (Merriam-Webster’s Collegiate Dict. 

(11th ed. 2006) p. 759.) However, contrary to CMTA’s suggestion, this does not 

necessarily mandate a precise numerical value for a margin of safety. For example, the 

word “amount,” in addition to meaning “the total number or quantity” can also mean, 

among other things, “the whole effect, significance, or import.” (Merriam-Webster’s 

Collegiate Dict. (11th ed. 2006) p. 42.) “Measure” can mean, among other things, “an 

adequate or due portion,” “a moderate degree,” “a measured quantity,” and “a step 

planned or taken as a means to an end.” (Merriam-Webster’s Collegiate Dict. (11th ed. 

2006) p. 769.) And “degree” can mean, among many other things, “the extent, measure, 

or scope of an action, condition, or relation.” (Merriam-Webster’s Collegiate Dict. (11th 

ed. 2006) p. 328.) In our view, these definitions do not mandate the employment of 
16

strictly numerical values to adjust the initial numerical PHG value as asserted by CMTA. 

Putting aside these definitions, we are of the opinion the term “margin of safety” has a 

more commonly understood meaning, employed here as a reasonable degree of latitude to 

ensure the health of all populations.

We further note we afford deference to OEHHA’s interpretation of the statute it is 

tasked with implementing. While “ ‘the proper interpretation of a statute is ultimately the 

court’s responsibility,’ ” we nevertheless give due weight to OEHHA’s construction. 

(California Manufacturers, supra, 64 Cal.App.5th at p. 280.) The Legislature enacted the

California Safe Drinking Water Act, among other things, “to ensure that the water 

delivered by public water systems of this state shall at all times be pure, wholesome, and 

potable.” (§ 116270, subd. (e).) As the Legislature stated: “Every resident of California 

has the right to pure and safe drinking water.” (§ 116270, subd. (a).) We conclude the 

Legislature has delegated interpretation of the statute to OEHHA, as the interpretation of 

section 116365 involves “ ‘ “ ‘an issue of interpretation [that] is heavily freighted with 

policy choices which the agency is empowered to make.’ ” ’ ” (California 

Manufacturers, supra, 64 Cal.App.5th at p. 280.) Safeguarding the right of every 

Californian to pure and safe drinking water, and, in so doing interpreting section 116365,

is a charge “ ‘ “ ‘heavily freighted with policy choices which [OEHHA] is empowered to 

make.’ ” ’ ” (California Manufacturers, at p. 280.) As such, we afford deference to its 

interpretation.

Additionally, as stated, the National Academy of Sciences (or a committee 

thereof) employed the same method as OEHHA here in identifying IUI as the basis for its 

risk assessment: “[T]he committee recommends that inhibition of iodide uptake by the 

thyroid in humans, which is the key biochemical event and not an adverse effect, should 

be used as the basis of the risk assessment. Inhibition of iodide uptake is a more reliable 

and valid measure, it has been unequivocally demonstrated in humans exposed to 

perchlorate, and it is the key event that precedes all thyroid-mediated effects of 
17

perchlorate exposure.” It is true, as asserted by CMTA, that, unlike OEHHA, the 

National Academy of Sciences does not operate under the mandates of section 116365. 

However, that this “society of distinguished scholars” advocated the method employed by 

OEHHA here further supports OEHHA’s determinations.

We conclude OEHHA properly considered IUI and established its PHG “at the 

level at which no known or anticipated adverse effects on health occur, with an adequate 

margin of safety.” (§ 116365, subd. (c)(1)(A).) OEHHA did not exceed its authority 

under the statute.

II

Conflict of Interest

A. Additional Background, CMTA’s Contentions, and Standard of Review

In 2005, OEHHA hired Dr. Steinmaus in the capacity of Public Health Medical 

Officer II. In 2007, 2010, and 2013, Steinmaus coauthored and published three studies 

involving perchlorate. The studies specified the views expressed therein were those of 

the authors and did not necessarily represent those of OEHHA.

CMTA asserts the PHG is void due to Dr. Steinmaus’s conflict of interest. It 

asserts the record establishes Steinmaus’s conflict under the common law conflict of

interest doctrine based on circumstances in which he would be tempted to serve his own 

interests. According to CMTA, through his publications, Steinmaus had already taken 

public positions on issues OEHHA was deciding in setting the PHG for perchlorate and 

his positions conflicted with other opinions in the scientific community. Therefore, 

according to CMTA, Steinmaus could not objectively participate in setting the PHG

because he had the conflicting interest in protecting his reputation and the propriety of his 

prior studies and positions he had publicly taken. CMTA contends that these 

circumstances demanded Steinmaus’s recusal from setting the PHG.

“We assess the court’s factual findings under the substantial evidence standard, 

but exercise independent judgment on legal issues. [Citations.] Legal issues include the 
18

interpretation of the governing statute or regulation and whether the agency took into 

account the relevant factors and acted ‘consistent with applicable law.’ ” (MandersonSaleh v. Regents of University of California (2021) 60 Cal.App.5th 674, 693, quoting 

Associated Builders & Contractors, Inc. v. San Francisco Airports Com. (1999) 

21 Cal.4th 352, 361.) Thus we exercise our independent judgment in determining 

whether the “ ‘common law doctrine against conflicts of interest’ ” (Clark v. City of 

Hermosa Beach (1996) 48 Cal.App.4th 1152, 1171 (Clark)) applies, and, if so, whether 

OEHHA acted “consistent with applicable law” (Associated Builders & Contractors, 

Inc., at p. 361).

B. The Common Law Conflict of Interest Doctrine

“ ‘[T]he common law doctrine against conflicts of interest . . . prohibits public 

officials from placing themselves in a position where their private, personal interests may 

conflict with their official duties.’ ” (Clark, supra, 48 Cal.App.4th at p. 1171.) This

doctrine extends to noneconomic conflicts of interest. (Id. at p. 1171, fn. 18.) “ ‘Actual 

injury is not the principle the law proceeds on. Fidelity in the agent is what is aimed at, 

and as a means of securing it the law will not permit him to place himself in a position in 

which he may be tempted by his own private interests to disregard those of his 

principal.’ ” (Id. at p. 1171.) A finding of self-interest sufficient to set aside a challenged

action “ ‘need not be based upon actual proof of dishonesty, but may be warranted 

whenever a public official, by reason of personal interest in a matter, is placed in a 

situation of temptation to serve his or her own purposes, to the prejudice of those for 

whom the law authorizes that official to act. . . . [A]n individual member ordinarily 

cannot vote on a matter in which that member . . . is interested. If the member does, the 

action taken by the body of which he or she is a member is invalidated. . . . Where the 

vote of a member interested is necessary to pass an ordinance or bylaw, such ordinance or 

bylaw is void, irrespective of how beneficial the ordinance may be.’ ” (Ibid., italics 

omitted.)
19

C. Analysis

The cases CMTA relies upon as applying the common law doctrine against 

conflicts of interest are factually distinguishable. However, of far greater importance, 

almost all involve quasi-judicial acts and challenges to them by writ petitions for 

administrative mandate pursuant to Code of Civil Procedure section 1094.5.

5

 (Petrovich 

Development Co., LLC v. City of Sacramento (2020) 48 Cal.App.5th 963; Fisher v. State 

Personnel Bd. (2018) 25 Cal.App.5th 1; Nasha v. City of Los Angeles (2004) 

125 Cal.App.4th 470 (Nasha); Clark, supra, 48 Cal.App.4th 1152.)

“ ‘[T]he terms “quasi-legislative” and “quasi-judicial” are used to denote . . . 

differing types of action. Quasi-legislative acts involve the adoption of rules of general 

application on the basis of broad public policy, while quasi-judicial acts involve the 

determination and application of facts peculiar to an individual case. [Citations.] Quasilegislative acts are not subject to procedural due process requirements while those 

requirements apply to quasi-judicial acts regardless of the guise they may take. . . .’ ” 

(Save Civita Because Sudberry Won’t v. City of San Diego (2021) 72 Cal.App.5th 957, 

983 (Save Civita), fn. omitted, quoting Beck Development Co. v. Southern Pacific 

Transportation Co. (1996) 44 Cal.App.4th 1160, 1188 (Beck Development Co.).) “The 

principle that procedural due process protections do not apply to quasi-legislative action 

is well established. [Citations.] ‘ “Legislative action generally is not governed by these 

procedural due process requirements because it is not practical that everyone should have 

a direct voice in legislative decisions; elections provide the check there.” ’ ” (Save 

Civita, at pp. 983-984, citing Western Oil & Gas Assn. v. Air Resources Board (1984) 37 

5 One of the cases on which CMTA principally relies is Noble v. Palo Alto (1928) 

89 Cal.App. 47. While Noble did not involve administrative mandamus, it also did not 

involve a quasi-legislative matter and, to our knowledge, it has not been applied in such a 

case.
20

Cal.3d 502, 525 & Horn v. County of Ventura (1979) 24 Cal.3d 605, 612-613.) This 

matter, involving OEHHA’s setting of the PHG for perchlorate in drinking water, is a 

quasi-legislative act.

“Quasi-legislative actions are generally reviewed by a proceeding in ordinary or 

traditional mandate (Code Civ. Proc., § 1085), in which judicial review is confined to the 

question whether the classification is arbitrary, capricious, or without reasonable or 

rational basis.” (Save Civita, supra, 72 Cal.App.5th at p. 984.) “Administrative 

mandamus (Code Civ. Proc., § 1094.5) is available only when ‘by law a hearing is 

required to be given, evidence is required to be taken, and discretion in the determination 

of facts is vested in the inferior tribunal, corporation, board, or officer . . . .’ ” (Ibid.; see 

also Beach & Bluff Conservancy v. City of Solana Beach (2018) 28 Cal.App.5th 244, 259 

[determination whether Code of Civ. Proc., §§ 1094.5 or 1085 applies does not depend on 

whether agency is required to hold evidentiary hearing, but instead turns on nature of 

challenged action; traditional mandamus under § 1085 applies to quasi-legislative 

decisions defined as those involving formulation of a rule to be applied to all future cases 

while administrative mandamus under § 1094.5 applies to quasi-judicial decisions which 

involve actual application of a rule to a specific set of facts].)

As stated, the majority of cases on which CMTA relies for applicability of the 

common law conflict of interest doctrine are cases addressing petitions for writs of 

administrative mandate involving quasi-judicial acts. (Petrovich Development Co., 

LLC v. City of Sacramento, supra, 48 Cal.App.5th 963; Fisher v. State Personnel Bd., 

supra, 25 Cal.App.5th 1; Nasha, supra, 125 Cal.App.4th 470; Clark, supra, 

48 Cal.App.4th 1152.) And, as stated, in such cases, rules of procedural due process 

apply. These include, among other things, hearings “ ‘ “ ‘before a reasonably impartial, 

noninvolved reviewer.’ ” ’ ” (Nasha, at p. 483.) In quasi-legislative matters, such as this, 

these procedural due process rules do not apply. (Save Civita, supra, 72 Cal.App.5th at 

p. 983; Beck Development Co., supra, 44 Cal.App.4th at p. 1188.) Regardless of the 
21

merits of CMTA’s contention that Dr. Steinmaus was conflicted, in the absence of the 

procedural due process safeguards applicable to quasi-judicial matters, we conclude the 

common law conflict of interest doctrine does not apply to these quasi-legislative 

proceedings.

CMTA offers no direct authority standing for the proposition that, despite the

inapplicability of procedural due process protections, the common law conflict of interest 

doctrine should nevertheless apply to circumstances such as these. While CMTA in its 

reply brief faults OEHHA for failing to cite any cases stating the common law conflict of 

interest doctrine applies only to quasi-judicial matters, what we find more significant is 

the lack of any case law we have found applying the doctrine to quasi-legislative matters 

such as this.

Among other things, in rejecting CMTA’s conflict of interest contention, the trial 

court relied on Friends of La Vina v. County of Los Angeles (1991) 232 Cal.App.3d 1446

(Friends of La Vina), disapproved on another ground in Western States Petroleum 

Assn. v. Superior Court (1995) 9 Cal.4th 559, 569-570 and footnote 2. Friends of La 

Vina was an appeal from a judgment granting a writ of mandate challenging the approval 

of a project and seeking a proper environmental impact report in compliance with the 

California Environmental Quality Act (CEQA). (Friends of La Vina, at p. 1450.) Insofar 

as relevant here, the court in Friends of La Vina stated: “The trial court’s ruling derived 

in large measure from what the court termed ‘general principles of conflict of interest,’ as 

applicable to applicants and their consultants. In so ruling, the court assumed an 

unwarranted role. The issue in this case is compliance with CEQA. To the extent 

policing of specific conflicts of interest might accurately be perceived as a legislative 

provision or purpose of CEQA, it could be pursued. But not otherwise. Except where the 

law clearly provides rules for identification and rectification of what might be termed 

conflicts of interest, that is a legislative not a judicial function.” (Id. at p. 1456, italics 

added.)
22

CMTA distinguishes Friends of La Vina on the ground that it was a CEQA case 

and the trial court’s employment of “general principles of conflict of interest” in its ruling 

was inappropriate given there was a statutory authorization for the challenged action. 

(Friends of La Vina, supra, 232 Cal.App.3d at pp. 1452-1453, 1456.) This is true, as far 

as it goes. However, the case nevertheless articulates a principle with which we agree: 

that we are not to identify and rectify purported conflicts of interest in areas where such 

has not previously been done, where there do not exist procedural due process 

protections, and where the choice to do so is more appropriately left to the Legislature. 

(See id. at p. 1456.)

CMTA also notes that the same appellate district that decided Friends of La Vina

decided Clark approximately five years later, when it “directly applied Noble’s common 

law principles and found a conflict of interest.” CMTA argues this suggests Friends of 

La Vina is strictly limited to its facts. Clark and Friends of La Vina were indeed both

decided by the Second Appellate District, although the cases were decided by different 

divisions. (Clark, supra, 48 Cal.App.4th 1152; Friends of La Vina, 

supra, 232 Cal.App.3d 1446.) What is more pertinent, however, is the fact, discussed 

ante, that Clark was an administrative mandate case implicating procedural due process 

protections.

Ultimately, here, we will not invoke the common law conflict of interest doctrine 

in circumstances in which, to our knowledge, it has never been applied. We are not 

persuaded it is appropriate to apply that doctrine here, where we are addressing a quasilegislative matter, as opposed to a quasi-judicial matter with its attendant procedural due 

process safeguards. We conclude the common law conflict of interest doctrine does not 

apply here. Accordingly, the PHG is not invalid as a result of any conflict of interest 

involving Dr. Steinmaus.
23

DISPOSITION

The judgment is affirmed. Respondents shall recover their costs on appeal. (Cal. 

Rules of Court, rule 8.278(a)(1), (2).)

 /s/

HOCH, J.*

I concur:

 /s/

RENNER, J.

*

 Retired Associate Justice of the Court of Appeal, Third Appellate District, assigned by 

the Chief Justice pursuant to article VI, section 6 of the California Constitution.
1

DUARTE, Acting P. J., Dissenting.

The California Safe Drinking Water Act (Health & Saf. Code § 116270 et seq.)

(Act)

1 directs that the Office of Environmental Health Hazard Assessment (OEHHA) 

protect the right to safe drinking water by setting aspirational public health goals (PHG) 

for acutely toxic substances, such as perchlorate, “at the level at which no known or 

anticipated adverse effects on health occur, with an adequate margin of safety.” 

(§ 116365, subd. (c)(1)(A).) Because OEHHA clearly did not do so in this case, and 

declined to do so in a manner that signals future noncompliance with the statute, I am 

compelled to dissent.

I do not dispute that the Act protects the quality of drinking water, and, in my 

view, PHGs and drinking water standards set by the State Water Resources Control 

Board are a welcome presence. But OEHHA’s power to set PHGs is not unrestricted; 

OEHHA must comply with plain language of the Act as it goes about the critical business 

of safeguarding the right to pure and safe drinking water for every Californian. 

Relying on an overly expansive definition of “anticipate,” the majority concludes 

that OEHHA complied with the Act’s requirements in this case because, “with the onset 

of IUI, adverse effects on health are anticipated.” (Maj. opn., ante, p. 14.) According to 

the majority, OEHHA is authorized to set the PHG to avoid a nonadverse health effect--

here iodide uptake inhibition (IUI)--so long as there exist “foreseeable, if not inevitable, 

adverse health effects.” (Maj. opn., ante, p. 14.) But the plain language of the Act 

requires OEHHA to set the PHG based on the level at which it expects the target 

substance to “cause or contribute to adverse health effects.” (§ 116365, subd. (c)(1), 

(c)(1)(A).) Here, rather than setting the PHG at the level at which OEHHA did not 

expect perchlorate exposure to cause or contribute to adverse health effects, OEHHA 

treated IUI as if it were an adverse health effect and set the PHG to avoid a 5 percent 

1

 Further undesignated statutory references are to the Health and Safety Code. 
2

reduction in iodide uptake. This methodology is not in compliance with the statute, 

because it is undisputed that a 5 percent reduction in iodide uptake does not cause or 

contribute to any adverse health effects. 

The majority also concludes that OEHHA is entitled to set the PHG below the 

level expressly required by the statute because the Act requires it to set the PHG “with an 

adequate margin of safety.” (Maj. opn., ante, pp. 15-16.) It reasons that “margin” 

provides OEHHA with “a reasonable degree of latitude” to set the PHG as OEHHA feels 

is necessary. (Maj. opn., ante, p. 16.) As I will explain, I disagree with the majority’s 

formulation of the phrase “with an adequate margin of safety,” and I view that 

formulation as at odds with OEHHA’s methodology in this case. I conclude instead that 

the statute requires OEHHA to first determine the level at which the target substance is 

anticipated to cause or contribute to adverse health effects--which OEHHA failed to do 

here--and then to apply an adequate margin of safety. 

Accordingly, I disagree with Part 1 of the majority opinion and dissent from its 

disposition affirming the trial court’s order.

DISCUSSION

I

Anticipated Adverse Effects on Health

There is no dispute but that IUI is not an adverse health effect. In its 2005 study, 

the National Academy of Sciences recognized when recommending that IUI be used as 

the point of departure for the perchlorate risk assessment that it was “recommending 

using a nonadverse effect [IUI] rather than an adverse effect.” OEHHA acknowledged 

this fact at various places throughout the record. For example, following the 2005 

National Academy of Sciences study, OEHHA recognized that IUI was “not harmful by 

itself” but “may lead to the harmful disruption of proper thyroid function.” In the 

technical support document accompanying the 2015 PHG, OEHHA observed that IUI “is 

the key event that leads to other possible effects from perchlorate exposure,” and that 
3

“[p]revention of iodide uptake inhibition prevents progression to the adverse health 

effects of perchlorate.” (Italics added.) Thus, rather than asserting that IUI is an adverse 

health effect, OEHHA acknowledged that it “treat[ed] [IUI] as it would an adverse event 

because it is in the direct causal pathway between perchlorate exposure and several 

important adverse events.” (Italics added.) 

OEHHA considered effects on thyroid hormone production--not IUI--to be an 

adverse health effect. It considered effects on thyroid hormone production to be adverse 

because “[a]ny downward shift in the mean level of the thyroid hormone T4 in a

population could increase the number of people who fall into the range of T4 values that 

are associated with high risks of either subtle or overt thyroid-related disease and 

toxicity.” (Italics added.) But in setting the PHG to avoid a 5 percent reduction in iodide 

uptake, OEHHA did not conclude that a 5 percent reduction in iodide uptake was

expected to cause the adverse health effect it had identified, reduced thyroid hormone 

production. Instead, OEHHA acknowledged that IUI “can lead to reduced thyroid 

hormone production” only if it were “severe enough.” (Italics added.) Indeed, the 2005 

National Academy of Sciences study recognized that IUI can cause reduction in thyroid 

hormone production “if iodide intake is very low.” 

The majority agrees that OEHHA set the PHG to avoid the onset of IUI. (Maj. 

opn., ante, p. 13.) In approving this practice, the majority considers the meaning of the 

word “anticipated,” settles on the synonym “foreseeable,” and then observes that 

“OEHHA could conclude, for example, the onset of IUI resulted in foreseeable adverse 

health effects to be dealt with in advance.” (Maj. opn., ante, pp. 13-14.) In other words, 

the majority appears to conclude that OEHHA may set a PHG below the level at which 

the target substance would be expected to cause or contribute to an adverse health effect, 

for the purpose of heading off those adverse health effects that might occur at higher 

concentrations of the substance. (Maj. opn., ante, p. 14.) But this reading of the statute 

authorizes OEHHA to set the PHG at any level below the level at which adverse health 
4

effects might be expected to actually occur for the purpose of heading off adverse health 

effects that are only foreseeable at concentrations of the target substance greater than the 

level set as the PHG. As one comment in opposition to the January 2011 draft PHG 

observed: “In essence, OEHHA seems to imply that any initiating events that have even 

the slightest potential to pose a downstream adverse physiological effect should be 

considered adverse. This is a critically important science policy change that has 

ramifications for future PHG risk assessments.” 

Indeed, under the majority’s reading, OEHHA could set the PHG at “zero” in 

order to head off adverse health effects that are foreseeable at greater concentrations of 

perchlorate. Were OEHHA authorized to set the PHG based on any precursor effect that 

was within the causal pathway between exposure to a contaminant and subsequent 

adverse health effects, the requirement that the PHG be set at the level at which no 

anticipated adverse health effects occur would be meaningless. (See State Farm General 

Insurance Co. v. Lara (2021) 71 Cal.App.5th 148, 179 [statutory interpretation aims to 

avoid rendering any words meaningless].) 

I interpret the term “anticipated” differently. “Dictionaries define ‘anticipated’ as 

meaning ‘to look forward to as certain’ [citation] and ‘[a]pprehended beforehand, looked 

for, expected’ [citation]. ‘The plain and ordinary meaning of “expect,” as reflected in 

dictionary definitions, is to anticipate, to consider probable or certain.’ ” (SN Sands 

Corp. v. City and County of San Francisco (2008) 167 Cal.App.4th 185, 193.) These 

definitions indicate that an “anticipated adverse health effect” is an adverse health effect 

that is at least probable or expected, if not necessarily certain. As relevant here, the word 

“level” is defined as “a position in a scale or rank (as of achievement, significance, or 

value)” or “a concentration of a constituent especially of a body fluid (such as blood).” 

(Merriam-Webster Collegiate Dict. (11th ed. 2003) p. 714, col. 2.) Applying these 

definitions, “level” clearly refers to a numerical value of the concentration of perchlorate 

in drinking water. Accordingly, the requirement that OEHHA set the PHG at “the level 
5

at which no . . . anticipated adverse effects on health occur” compels OEHHA to set the 

PHG at the concentration of the target substance (the level) at which OEHHA determines 

it is probable or expected that adverse health effects will occur. Thus, I agree with the 

majority’s observation that “OEHHA could set the PHG at a level where there exist 

foreseeable, if not inevitable, adverse health effects.” (Maj. opn., ante, p. 14.) 

My disagreement stems from the indisputable reality that there are no foreseeable 

adverse health effects associated with a 5 percent reduction in iodide uptake. OEHHA 

set the PHG at a level that avoids IUI, a nonadverse precursor effect, well below the level 

at which it was even arguably foreseeable that this precursor effect would lead to adverse 

health effects. Rather than attempting to determine the concentration of perchlorate that 

would be expected to cause or contribute to adverse health effects, as the statute requires, 

OEHHA simply treated IUI as if it were an adverse health effect. 

To summarize my points thus far: it is undisputed that the Act provides that 

OEHHA “shall” set the PHG “at the level at which no known or anticipated adverse 

effects on health occur, with an adequate margin of safety.” (§ 116365, subd. (c)(1)(A); 

italics added.) It is also undisputed that IUI is not an adverse health effect. Finally, it is 

undisputed that a 5 percent reduction in iodide uptake is not expected to cause or 

contribute to adverse health effects. The statute does not authorize OEHHA to set the 

PHG to avoid a precursor health effect below the level at which the precursor effect 

would be expected to cause or contribute to adverse health effects. 

I next discuss the majority’s reliance on what it deems the “qualifier,” the phrase 

“with an adequate margin of safety,” and explain why I find it unconvincing. (Maj. opn., 

ante, p. 15.)

II

Adequate Margin of Safety

The majority concludes that OEHHA was entitled to set the PHG to avoid a 

nonadverse precursor health effect because section 116365, subdivision (c)(1)(A) 
6

requires OEHHA to set the PHG “with an adequate margin of safety,” which it interprets 

as generally providing OEHHA with a “reasonable degree of latitude” in setting the PHG. 

(Maj. opn., ante, pp. 15-16.) Although I do not disagree that OEHHA has some latitude, 

I read the statute to require that OEHHA establish a margin of safety from the level at 

which no known or anticipated adverse health effects occur. Indeed, that is what OEHHA 

purported to do here, as I will explain.

To ascertain the meaning of section 116365, subdivision (c)(1)(A) and its 

requirement that “[i]f the contaminant is an acutely toxic substance, the [PHG] shall be 

set at the level at which no known or anticipated adverse effects occur, with an adequate 

margin of safety,” I begin with its grammar. In interpreting the meaning of the provision, 

“[w]e must presume that the Legislature intended ‘every word, phrase and provision . . . 

in a statute . . . to have meaning and to perform a useful function.’ ” (Garcia v. 

McCutchen (1997) 16 Cal.4th 469, 476.) The provision begins with a triggering clause: 

“If the contaminant is an acutely toxic substance.” (See Chicago Manual of Style (17th 

ed. 2017) § 6.24.) The sentence then includes a subject (the PHG), a modal verb (shall 

be), the main verb (set), and an adverbial prepositional phrase (“at the level”), which is 

two or more words that function together as an adverb to modify a verb. (Id., § 5.161.) 

Here, “at the level” tells us where the PHG shall be set (at the level). The sentence 

concludes with two adjectival prepositional phrases modifying “the level.” These 

prepositional phrases inform that the level at which the PHG is to be set is the one “at 

which no known or anticipated adverse effects on health occur,” and “with an adequate 

margin of safety.” Although each of these phrases consists of its own grammatical 

subparts, each phrase modifies “the level.” 

As I discussed ante, the Act requires OEHHA to set the PHG at the numerical 

value of the concentration of perchlorate in drinking water (the level) at which OEHHA 

does not expect that adverse health effects will occur. From that numerical value, the Act 

requires OEHHA to establish “an adequate margin of safety.” As a modification of a 
7

numerical value, the most natural reading of the word “margin” is “a spare amount or 

measure or degree allowed or given for contingencies or special situations,” or “measure 

or degree of difference.” (Merriam-Webster Collegiate Dict. (11th ed. 2003) p. 759, cols. 

1-2.) In other words, the “adequate margin of safety” is a numerical reduction of the 

level as previously defined as necessary to ensure public safety. 

The majority concludes that the statute’s reference to the term “margin” authorizes 

OEHHA to set the PHG to avoid a nonadverse health effect because it provides a general 

degree of latitude “to account for uncertainty so as to ensure public health.” (Maj. opn., 

ante, p. 15.) I disagree with that conclusion. First, as stated, “margin” modifies the level 

at which the PHG is set (a numerical value), not the nature of the health effect--whether 

adverse or nonadverse--used as the basis for determining the level. In other words, the 

statute would authorize OEHHA to set the PHG to avoid a nonadverse health effect only 

if “adequate margin of safety” modified “no known or anticipated adverse health effects,” 

rather than “the level.” 

Second, OEHHA’s methodology indicates that it did not treat IUI as an adverse 

effect for purposes of establishing a margin of safety, but instead acted to establish the 

permissible margin after determining a level, as contemplated by the statute. In setting 

the PHG, OEHHA first determined the level at which perchlorate exposure would cause a 

5 percent reduction in iodide uptake, which it justified by recognizing that it “treat[ed] 

[IUI] as it would an adverse effect.” In other words, OEHHA first determined the level at 

which it expected perchlorate exposure to cause a (non)adverse health effect. After 

establishing the level of perchlorate estimated to cause a 5 percent decrease in iodide 

uptake, OEHHA applied two separate margins of safety. It applied an uncertainty factor 

of 10 to “calculate a dose that would address inter-individual variability among humans 

and be protective of those who are likely to be sensitive to the effects of perchlorate,” 

including infants, which it noted “are particularly susceptible to perchlorate.” It also 

calculated the PHG using the 95th percentile of infant water intake per kilogram of 
8

bodyweight, based on data indicating that infants drink more water on a body weight 

basis than other sensitive groups. Thus, OEHHA expressly acknowledged that it was 

treating IUI as it would an adverse effect, and then it separately and subsequently applied 

margins of safety to ensure public health.

Based on the grammatical structure of the Act and OEHHA’s methodology in 

establishing the PHG, I cannot agree that the Act authorized OEHHA to proceed directly 

to establishing an adequate margin of safety by setting the PHG based on avoidance of a 

nonadverse health effect, as the majority now holds. Indeed, without first ascertaining 

the level at which no known or anticipated adverse health effects occur, from which the 

margin of safety is then applied, there is no way to determine whether the margin is 

“adequate.” 

III

Conclusion

Although the majority concludes that we should defer to OEHHA’s interpretation

of the Act, it also correctly notes that this court ultimately decides what the statute 

requires. (Maj. opn., ante, p. 16.) And although the majority observes that the National 

Academy of Sciences has embraced OEHHA’s approach, specifically recommending that 

IUI, while admittedly “not an adverse effect,” should nonetheless “be used as the basis of 

the risk assessment” (maj. opn., ante, p. 16), this recommendation is not relevant to our 

analysis of the relevant statutory requirements and whether OEHHA complied with them 

here. Further, although the majority correctly states several times that the statute 

establishes the right of all Californians to safe drinking water, an observation with which 

I readily agree, the existence of that right is not at issue here. At issue is the manner in 

which the Act requires that right be ensured. 

Based on the foregoing, I would conclude the 2015 PHG does not conform to the 

Act’s requirements. I would reverse the trial court’s October 7, 2020, order denying the 

Association’s petition for writ of mandate and direct the issuance of a peremptory writ of 
9

mandate directing OEHHA to vacate the 2015 PHG and to establish a new PHG that 

complies with the requirements of section 116365. Because the majority instead affirms 

the trial court’s order, I respectfully dissent.

 /s/

DUARTE, Acting P. J.