Environmental Engineering Reference
In-Depth Information
bought in stores and restaurants, that may be domestic or
imported. In the United States, the USEPA is responsible for
addressing issues of mercury in noncommercial fi sh, while
the USFDA is responsible for addressing issues of mercury
in commercial fi sh. Although most of the fi sh consumed
in the United States comes from commercial sources (Sun-
derland, 2007), most guidance on safe fi sh consumption
focuses on noncommercial fi sh (USEPA, 2007).
In the United States, guidelines for consumption of non-
commercial fi sh are issued in the form of fi sh advisories,
which are nonregulatory, voluntary recommendations.
The fi rst such fi sh advisories were issued in the early 1970s
(USEPA, 2000). The objective of an advisory is to enable
people to make informed decisions about their fi sh-eating
behaviors. A typical advisory includes information about
contaminants of concern and the benefi ts of eating fi sh,
and provides guidance on how to minimize contaminant
exposure. Included in this guidance may be information on
how to choose fi sh based on their source, size, and species;
advice on how to prepare fi sh; and recommendations on
how frequently certain types of fi sh may be consumed, if at
all. Advisories may be issued for the general population or
for specifi c populations.
assessment are hazard identifi cation, dose-response assess-
ment, exposure assessment, and risk characterization. A
risk assessment considers technical information such as the
dose at which a particular contaminant is likely to result
in adverse health effects in humans, as well as additional
factors that infl uence risk, such as any hardships that may
result from fi shing restrictions or any characteristics of a
particular population that may make it more or less sensi-
tive to a contaminant. Through risk assessment, risk-based
fi sh-consumption limits are developed that are the basis of
fi sh advisories. For noncarcinogenic contaminants such as
mercury, basic consumption limits for a particular location
are calculated from fi ve variables:
.
a dose-response variable known as the reference
dose,
.
the average body weight for the human population of
interest,
.
the measured concentration of a contaminant (from
the fi sh sampling and analysis step) in a given species
of fi sh,
.
the average fi sh meal size of the population of interest,
and
.
a specifi ed time period.
Developing Fish Advisories
The USEPA provides dose-response variable values for
multiple contaminants. As of 2011, the reference dose for
mercury was 0.1 µg/kg of body weight per day, but some
questions have been raised about the validity of this value
(Stern and Smith, 2003; Mahaffey et al., 2009). The USEPA
also provides default values for the acceptable risk level,
body weight, and meal size variables, but recommends that
agencies adjust these values according to their specifi c situ-
ations to arrive at appropriate consumption limits. Con-
sumption limits may be refi ned further based on additional
factors that infl uence risk, as mentioned previously. Typi-
cally, consumption limits are expressed as the amount of
fi sh that can safely be consumed per day, or the number
of meals of fi sh that can safely be consumed over a given
period.
The third step of the USEPA's approach, risk management,
involves combining the scientifi c information obtained in
the risk-assessment step with various policy considerations
to arrive at a design for a fi sh advisory program. A program
can be designed to use any of a number of options for man-
aging fi sh consumption, ranging from taking no action,
to issuing specifi c advisories, to issuing fi shing bans. The
design of an advisory program is determined in part by fac-
tors such as the goals the program is intended to achieve,
the availability of staff and fi nancial resources, and local
issues—such as the potential impacts of an advisory on tra-
ditional practices, tourism, or community relations—that
should be considered.
The fourth and fi nal step of the USEPA's approach, risk
communication, involves determining the best way to suc-
cessfully deliver fi sh-consumption advice to the population
State, local, and tribal agencies hold primary responsibil-
ity for developing and issuing advisories for noncommer-
cial, locally caught fi sh in the United States. Each agency
makes its own determinations about the scope and extent
of its contaminant monitoring, about the decision-making
process used to issue an advisory, and about the specifi c
advice that is issued (USEPA, 2007). However, the USEPA
encourages agencies to follow the standardized methods
contained in its
Guidance for Assessing Chemical Contami-
nant Data for Use in Fish Advisories
manual (USEPA, 2000).
These methods are summarized here in order to illustrate
the basic process of the development of fi sh advisories.
The USEPA manual outlines four main steps for develop-
ing and issuing advisories: (1) fi sh sampling and analysis,
(2) risk assessment, (3) risk management, and (4) risk com-
munication. The fi rst step involves screening local waters
to identify areas where targeted fi sh species have concen-
trations of targeted contaminants above predetermined
screening values. A screening value represents the concen-
tration of a contaminant in fi sh that is of potential public
health concern, and it is used as a threshold value against
which to compare monitoring data. Screening is followed
by more intensive sampling and analysis of tissues from
fi sh in potentially problematic areas. Through the follow-
up sampling and analysis, size-specifi c levels of contamina-
tion in targeted fi sh species are determined, and the magni-
tude and geographic extent of contamination are assessed.
The second step involves using risk-assessment proce-
dures to evaluate the nature and extent of risk to the popu-
lation that consumes local fi sh. The general steps in a risk
