UNITED STATES COURT OF APPEALS FOR THE D.C. CIRCUIT


CHLORINE CHEM CNCL

v.

EPA


98-1627a

D.C. Cir. 2000


*	*	*


Williams, Circuit Judge: The Safe Drinking Water Act  ("SDWA" or the
"Act") directs the Environmental Protection  Agency to set standards
for the regulation of covered drink- ing water contaminants. For each
EPA sets a "maximum  contaminant level goal" ("MCLG"), defined as "the
level at  which no known or anticipated adverse effects on the health 
of persons occur and which allows an adequate margin of  safety." 42
U.S.C. s 300g-1(b)(4)(A). The MCLG is some- what aspirational. After
having set it, EPA is to promulgate  an enforceable standard, known as
a maximum contaminant  level ("MCL"), which takes practical
considerations into ac- count while remaining "as close to the [MCLG]
as is feasible."  Id. s 300g-1(b)(4)(B).


In March 1998 EPA concluded that chloroform, a drinking  water
contaminant, exhibits a "nonlinear mode of carcinogenic  action."
Notice of Data Availability: National Primary 


Drinking Water Regulations: Disinfectants and Disinfection  Byproducts,
63 Fed. Reg. 15,674, 15,686/1 (1998). In other  words, exposures to
chloroform below some threshold level  pose no risk of cancer. But in
promulgating the MCLG it  retained the existing standard of zero,
which was based on  the previously held assumption that there was no
safe thresh- old. Final Rule: National Primary Drinking Water Regula-
tions: Disinfectants and Disinfection Byproducts, 63 Fed.  Reg.
69,390, 69,398/3 (1998) ("Final Rule"). EPA justified its  action on a
variety of grounds, including an alleged need to  consult the report
of its Science Advisory Board ("SAB"),  which would not be available
until after the statutory deadline  for rulemaking had expired.
Petitioners, including the Chlo- rine Chemistry Council, a trade
association comprised of  chlorine and chlorine product manufacturers,
petitioned this  court for review, arguing that EPA violated its
statutory  mandate to use the "best available" evidence when imple-
menting the provisions of the Safe Drinking Water Act. 42  U.S.C. s


* * *


Chloroform, a "nonflammable, colorless liquid," Proposed  Rule:
National Primary Drinking Water Regulations: Disin- fectants and
Disinfection Byproducts, 59 Fed. Reg. 38,668,  38,694/2 (1994), is one
of four compounds that together are  classed as "Total
Trihalomethanes" ("TTHMs"). These are  byproducts of chlorination, the
most widely used technique  for ensuring the safety of drinking water.
Chlorination plays  a significant role in the control of microbial
pathogens and in  turn in the protection of public health; but on the
basis of  rodent tumor data the Agency has concluded that chloroform, 
a byproduct of this process, acts as a probable human carcino- gen.


On July 29, 1994 EPA issued a proposed rule on disinfec- tants and
disinfection byproducts in water. This included a  zero MCLG for
chloroform, based on EPA's finding of an  absence of data to suggest a
threshold level below which there  would be no potential carcinogenic
effects. Id. The Agency's 


default method of inferring risk at exposure levels for which  it has
no adequate data is linear extrapolation from cancer  incidence
inferred at exposures for which it does have data.  See EPA's Proposed
Guidelines for Carcinogen Risk Assess- ment, 61 Fed. Reg. 17,960,
17,968/3 (1996). Thus, either if  the evidence supports linearity, or
if there is "insufficient"  evidence of nonlinearity, EPA assumes that
if a substance  causes cancer at any exposure it will do so at every
non-zero  exposure (though with cancer incidence declining with expo-
sure). But EPA acknowledges its authority "to establish  nonzero MCLGs
for carcinogens if the scientific evidence"  indicates that a "safe
threshold" exists. See Final Rule, 63  Fed. Reg. at 69,401/2. And
petitioners here assume the  validity of the linear default


In 1996 Congress amended the SDWA, enshrining in the  statute a
timetable previously set by EPA for rules relating  to disinfectants
and disinfection byproducts associated with  water treatment. 42
U.S.C. s 300g-1(b)(2)(C); Proposed  Rule: National Primary Drinking
Water Regulations: Moni- toring Requirements for Public Drinking Water
Supplies, 59  Fed. Reg. 6332, 6361 (1994). The relevant deadline here
was  November 1998. In preparation for the necessary rulemak- ing EPA
formed an advisory group in 1997 whose purpose  was "to collect,
share, and analyze new information and data,  as well as to build
consensus on the regulatory implications of  this new information."
Notice of Data Availability: National  Primary Drinking Water
Regulations: Interim Enhanced  Surface Water Treatment Rule, 62 Fed.


On the basis of the committee's findings and recommenda- tions, EPA in
November 1997 published a Notice of Data  Availability ("NODA"), 62
Fed. Reg. 59,388 (1997), and in  1998 it published a second NODA
specific to chloroform, 63  Fed. Reg. 15,674 (1998). Among the
findings it discussed  were those arrived at by a panel of experts
organized by the  International Life Sciences Institute. The panel,
whose work  was subject to independent peer review and was convened 
under the auspices of the EPA, concluded on the basis of  chloroform's
mode of action that although it was "a likely 


carcinogen to humans above a certain dose range, [it was]  unlikely to
be carcinogenic below a certain dose range." Id.  at 15,685/1. The
panel recommended "the nonlinear [ ] or  margin of exposure approach
[as] the preferred approach to  quantifying the cancer risk associated
with chloroform expo- sure." Id. at 15,686/1.


EPA agreed. It said that "[a]lthough the precise mecha- nism of
chloroform carcinogenicity is not established," never- theless "the
chloroform dose-response should be considered  nonlinear." Id. at
15,685/3. Rather than operating through  effects on DNA, which is
consistent with linearity, chloroform  evidently works through
"cytotoxicity" (i.e., damage to the  cells) followed by regenerative
cell proliferation. Id. Em- ploying the threshold approach that it
found was entailed by  chloroform's mode of action, EPA then
calculated an MCLG  of 600 parts per billion ("ppb"), based solely on
carcinogenici- ty. Id. at 15,686/2. This level built in a 1000-fold
margin of  error in relation to the maximum safe dosage implied from 
the animal studies used by EPA. Id. But because even  lower chlorine
doses cause liver toxicity (a non-cancer effect),  EPA proposed an


When EPA came to promulgate its final rule in December  1998, however,
its MCLG was again zero. Final Rule, 63  Fed. Reg. at 69,398/3. It
stuck with 1994's zero level despite  its explicit statement that it
now "believe[d] that the underly- ing science for using a nonlinear
extrapolation approach to  evaluate the carcinogenic risk from
chloroform is well found- ed." Id. at 69,401/1. It justified the
action on the basis that  "additional deliberations with the Agency's
SAB on the ana- lytical approach used" and on the underlying
scientific evi- dence were needed "prior to departing from a long-held
EPA  policy." Id. at 69,399-69,401. It could not complete such 
additional deliberations by the November 1998 statutory  deadline,
and, moreover, the rulemaking would not affect the  enforceable MCL


After briefing on the petition for review at issue here, but  before
oral argument, EPA moved for a voluntary remand to  consider the SAB
report on chloroform that would soon be 


available. But EPA made no offer to vacate the rule; thus  EPA's
proposal would have left petitioners subject to a rule  they claimed
was invalid. We denied the motion.


On February 11, 2000, the day of oral argument, EPA  released a draft
report by the SAB on chloroform. See  Draft, Chloroform Risk
Assessment Review, February 10,  2000 (visited March 27, 2000) . The
report concluded that chloro- form exhibits a "cytotoxic" mode of
action. Such a mode of  action (unlike a "genotoxic" mechanism, which
acts directly on  a cell's DNA) involves no carcinogenic effects at
low doses;  thus a nonlinear approach is "scientifically reasonable."
Id.  at 17. After consideration of the draft SAB report, EPA  stated
that it "no longer believes that it should continue to  defend its
original decision," and moved that this court vacate  the MCLG. Motion
for Vacatur, at 2 (February 24, 2000).


* * *


EPA in its motion to vacate concedes that "the discussion  on standing
at oral argument indicates that petitioners may  indeed meet minimum
requirements for standing," a neces- sary precursor to our providing
any relief beyond the vacatur  proposed by EPA. Given our independent
duty to be sure of  our jurisdiction, Floyd v. District of Columbia,
129 F.3d 152,  155 (D.C. Cir. 1997), we address EPA's now evidently
aban- doned jurisdictional arguments.


EPA's brief contends that petitioners lack Article III  standing
because they have not demonstrated injury-in-fact  from the MCLG.
Lujan v. Defenders of Wildlife, 504 U.S.  555, 560-61 (1992). We have
already held, in International  Fabricare Inst. v. EPA, 972 F.2d 384,
390 (D.C. Cir. 1992),  that an association of dry cleaning businesses
had standing to  attack EPA's setting of a zero MCLG for a contaminant
used  in their business. There we pointed to the MCLG's link to  risks
of "greater liability under the Comprehensive Environ- mental
Response, Compensation and Liability Act ('CERC- LA'), 42 U.S.C. ss
9601-9675," id., which under some circum- stances may entail remedial
action achieving "a level or 


standard of control which at least attains Maximum Contami- nant Level
Goals established under the Safe Drinking Water  Act," 42 U.S.C. s
9621(d)(2)(A).


EPA challenges petitioners' theory on several grounds.  First, it says,
its regulations provide that when a zero MCLG  is set, it is the MCL,
not the MCLG, that is used to set  cleanup standards. 40 CFR s
300.430(e)(2)(i)(C). In this  case, says EPA, the MCL set for TTHMs
would control.  Since there is no suggestion that the effective MCL
will  imminently be affected by the zero MCLG, and petitioners  have
not challenged the MCL for TTHMs, EPA argues that  they have failed to
demonstrate an injury.


But the MCL for TTHMs is in fact not dispositive in  setting the
cleanup standard for chloroform. EPA has in the  past rejected use of
the TTHM MCL for that purpose, saying  that that MCL is "based on an
analysis evaluating the health  benefits of chlorinating public
drinking water supplies against  the detrimental effects of the
production of trihalomethanes  as a result of chlorinating those
supplies." U.S. EPA, Super- fund Record of Decision, Stringfellow
Hazardous Waste Site,  at 25 (Sept. 30, 1990). Instead, EPA has set
chloroform  cleanup goals as low as 6 ppb (far below the 100 ppb MCL
for  TTHMs), based on an assumption that chloroform poses a  risk of
cancer at any dose, but that 6 ppb would yield an  acceptable cancer
risk of one-in-a-million. Id. Thus EPA's  actual practice belies its
claims here as to the inconsequential- ity of the chloroform MCLG.


EPA also argues that unlike the petitioners in Internation- al
Fabricare, neither petitioners nor their members here have  yet been
subjected to cleanup costs for chloroform contamina- tion, and thus
have not demonstrated a "genuine threat" of  CERCLA liability. EPA's
Br. at 21. But in a forward- looking suit the petitioners' subjection
to past injury is rele- vant primarily as it may shed light on whether
the challenged  action has a "substantial probability" of causing
injury. Flor- ida Audubon Soc'y v. Bentsen, 94 F.3d 658, 666 (D.C.
Cir.  1996) (en banc). CERCLA imposes joint and several liability  on
"any person who by contract, agreement, or otherwise 


arranged for disposal or treatment ... of hazardous sub- stances owned
or possessed by such person." 42 U.S.C.  s 9607(a)(3). In light of
petitioners' contention that they face  liability "for the cleanup of
chloroform at Superfund sites  across the country," Petitioners' Reply
Br. at 16, we find it at  least substantially probable that a zero
MCLG, as compared  with a nonzero one, will expose them to higher
cleanup costs.


* * *


Before turning to the merits of petitioners' claim, we note  EPA's
contention that its motion to vacate obviates the "need  for the Court
to issue an opinion." Motion for Vacatur, at 3.  But we have no reason
to believe that mere vacatur provides  an adequate remedy if, as we
ultimately conclude, EPA's  action was unlawful. Petitioners request
that we instruct  EPA to "promulgate a non-zero MCLG using the best
avail- able peer-reviewed science." Petitioners' Initial Br. at 34. 
But EPA has not indicated an intention to take such action  upon
vacatur. Moreover, EPA makes no claim that the 1994  zero MCLG would
not be automatically revived by vacatur of  the 1998 rule. Our
agreement with the petitioners on the  rule's lawfulness will thus
bring issues of remedy into play.


On the merits petitioners argue that EPA's decision to  adopt a zero
MCLG in the face of scientific evidence estab- lishing that chloroform
is a threshold carcinogen was inconsis- tent with the Safe Drinking
Water Act. Section  300g-1(b)(3)(A) of the Act states unequivocally
that "to the  degree that an Agency action is based on science, the
Admin- istrator shall use ... the best available, peer-reviewed
science  and supporting studies conducted in accordance with sound 
and objective scientific practices." In promulgating a zero  MCLG for
chloroform EPA openly overrode the "best avail- able" scientific
evidence, which suggested that chloroform is a  threshold


EPA provides several arguments in defense of its action.  First, it
argues that to establish a non-zero MCLG would be a  "precedential
step," that represents "a major change in the  substance of regulatory
decisions related to chloroform." 


EPA's Br. at 28-29. We do not doubt that adopting a  nonzero MCLG is a
significant step, one which departs from  previous practice. But this
is a change in result, not in  policy. The change in outcome occurs
simply as a result of  steadfast application of the relevant rules:
first, the statutory  mandate to set MCLGs at "the level at which no
known or  anticipated adverse effect on the health of persons occur,"
42  U.S.C. s 300g-1(b)(4)(A), as determined on the basis of the  "best
available" evidence; and second, EPA's Carcinogen  Risk Assessment
guidelines, stating that when "adequate data  on mode of action show
that linearity is not the most reason- able working judgment and
provide sufficient evidence to  support a nonlinear mode of action,"
the default assumption  of linearity drops out. Proposed Guidelines
for Carcinogen  Risk Assessment, 61 Fed. Reg. at 17,969/1. The fact
that  EPA has arrived at a novel, even politically charged, outcome 
is of no significance either for its statutory obligation or for 
fulfillment of its adopted policy.


Second, and similarly, EPA supports its action on the basis  that "it
could not complete the deliberations with the SAB"  before the
November 1998 deadline. EPA's Br. at 29; Final  Rule, 63 Fed. Reg. at
69,399/1. But however desirable it may  be for EPA to consult an SAB
and even to revise its conclu- sion in the future, that is no reason
for acting against its own  science findings in the meantime. The
statute requires the  agency to take into account the "best available"
evidence. 42  U.S.C. s 300g-1(b)(3)(A) (emphasis added). EPA cannot
re- ject the "best available" evidence simply because of the 
possibility of contradiction in the future by evidence unavail- able
at the time of action--a possibility that will always be  present.


Third, EPA justifies its decision not to adopt a nonzero  MCLG on the
basis that it had to reevaluate one of its  underlying technical
assumptions--that ingestion of chloro- form in drinking water accounts
for 80% of total exposure to  chloroform. As it stated in its final
rule, EPA is currently  considering use of a 20% relative source
contribution for  drinking water, which would lower the MCLG to 70
ppb.  Final Rule, 63 Fed. Reg. at 69,399/3. Along these lines, 


EPA's counsel conceded at oral argument that a science- based MCLG
would fall into the interval between 70 and 300  ppb. The uncertainty
on this issue may have provided sup- port for choosing the lowest
nonzero MCLG from within that  interval, but none for choosing an MCLG
outside the range of  uncertainty.


Fourth, EPA argues that since the final MCL for TTHMs  is unaffected,
the MCLG has no actual effect, and thus EPA's  decision to publish an
MCLG of zero pending further review  of the scientific evidence was
entirely reasonable. In light of  our analysis of the standing issue,
the no-effect premise is  plainly incorrect. Even if it were correct,
we fail to see why  it would justify EPA's disregard of its own
scientific findings.


Finally, EPA argues that its statements in the 1998 Notice  of Data
Availability do not represent its "ultimate conclu- sions" with
respect to chloroform, and thus in adopting a zero  MCLG it did not
reject what it considered to be the "best  available" evidence. In
fact, the zero MCLG merely repre- sented an "interim risk management
decision" pending the  final SAB report. EPA's Br. at 35. We find
these semantic  somersaults pointless. First, whether EPA has adopted
its  1998 NODA as its "ultimate conclusion" is irrelevant to  whether
it represented the "best available" evidence. All  scientific
conclusions are subject to some doubt; future, hypo- thetical findings
always have the potential to resolve the  doubt (the new resolution
itself being subject, of course, to  falsification by later findings).
What is significant is Con- gress's requirement that the action be
taken on the basis of  the best available evidence at the time of the
rulemaking.  The word "available" would be senseless if construed to
mean  "expected to be available at some future date." Second, EPA 
cannot avoid this result by dubbing its action "interim." The  statute
applies broadly to any "[a]gency action"; whether the  action is


* * *


Although we agree with petitioners that the zero MCLG for  chloroform
is inconsistent with the Safe Drinking Water Act 


and that it should be vacated, we are unclear as to what  further
remedy petitioners seek. In their opening brief  petitioners requested
that this Court instruct EPA to "pro- mulgate a non-zero MCLG using
the best available peer- reviewed science as identified in the March
31, 1998 NODA  and the December 16, 1998 Final Rule on an expeditious 
timetable to be specified by the Court." Petitioners' Initial  Br. at
34. At oral argument, however, counsel for petitioners  conceded that
this request was a misstatement, and that EPA  should be allowed, and
required, to consider the new SAB  report as well. Further, the
consequences of simple vacatur  are themselves unclear. Accordingly,
we will schedule brief- ing on the parties' positions as to remedy.


Finding the Agency's December 1998 rule adopting a zero  MCLG for
chloroform to be arbitrary and capricious and in  excess of statutory
authority, see 5 U.S.C. s 706(2)(A) & (C),  we vacate the rule. A
separate order on briefing additional  remedies will issue shortly.


So ordered.