Implementing food-based dietary guidelines for - United Nations ...

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Most of this discussion will draw on recent considerations
of micronutrients [1, 2]. Additionally, there is
a current international collaboration exploring systematic
safety assessments of intakes of amino acids [3–5].
Toxicological risk analysis and assessment
The values derived by the risk assessment are estimates
of the quantity of a substance that can be ingested daily
over a lifetime without appreciable risk to health and
are termed health-based guidance values [6–9]. These
include the acceptable daily intake (ADI) [6]) and the
tolerable intake (TI), which may be weekly (TWI) or
daily (TDI) [8]. The ADI is applied for estimates of safe
exposure for food additives, i.e., for chemicals that are
permitted to be used in foods, and the TDI relates to
contaminants and pollutants. The US Environmental
Protection Agency has replaced ADI and TDI with the
term reference dose (RfD), which has been defined
as an estimate of the daily exposure in the human
population that is likely to be without an appreciable
risk of deleterious effects during a lifetime. All these
definitions are framed to avoid implying that they
are absolutely “safe”; they are advisory (although they
might subsequently be translated into regulations) and
are the products of a systematic process of risk analysis,
of which risk assessment is one element.
Risk analysis is “a detailed examination, including
risk assessment, risk evaluation and risk management
alternatives, performed to understand the nature of
unwanted, negative consequences to human life, health,
property or the environment; an analytic process to
provide information regarding undesirable events:
the process of quantification of the probabilities and
expected consequences of identified risks” [10].
The definitions used in the established process vary
among the agencies involved, but with the maturation
of the discipline and increased international and interagency
harmonization, the definitions are very close and
common wordings are emerging.
In this process, the definition of a hazard is “the
inherent property of a chemical to cause adverse effects
depending upon the level of intake.” The modification
of this to suit the needs of nutritional risk assessment
(see above) is straightforward [1]. An adverse effect is
“a change in morphology, physiology, growth, development
or lifespan of an organism which results in
impairment of functional capacity or impairment of
capacity to compensate for additional stress or increase
in susceptibility to the harmful effects of other environmental
influences. Decisions on whether or not any
effect is adverse require expert judgment” [7]. Again,
this is little different from the definition derived for
nutritional risk assessment.
A risk is “the probability or likelihood that a hazard
will actually cause harm to an individual or popula-
tion group”
In the model developed by the Food and Agriculture
Organization/World Health Organization (FAO/WHO)
and the Codex Alimentarius, Risk Analysis comprises
three distinct steps: risk assessment, risk management,
and risk communication. Although each is a distinct
step, collectively they are intended to be a coherent
and fluently progressive entity. This is a well-accepted
model, because it provides a structure that ensures that
any uncertainties, variabilities, or assumptions involved
in the assessment can be identified, thereby enabling
and encouraging a transparent explanation of the
means by which these issues are compensated.
Risk assessment
P. J. Aggett
In practice, the first step in risk analysis is that of
“problem formulation,” i.e., setting the key purpose
and objective of the exercise. Usually this is done by
the risk managers and regulators who will be responsible
for managing the risk of any particular exposure
and communicating to the public about the risk and
the strategy to manage it.. Often, but not necessarily
always, problem formulation may involve consultation
with those who have the task of assessing the hazards
and any attendant risks.
Once the problem has been set, the first phase in risk
analysis, risk assessment, can start. Since this involves
identifying and prioritizing hazards and the exposures
at which they happen, this is the process that is most
relevant for this paper. Risk assessment comprises four
stages: hazard identification, hazard characterization
(sometimes called dose–response assessment), exposure
assessment, and risk characterization. Each is
briefly described later, but in essence they involve first
a full review of all relevant information and a qualitative
identification and evaluation of all adverse effects
associated with high exposures (hazard identification),
followed by a quantitative estimation of risk for each
adverse effect (hazard characterization). Assessment of
dose–response often includes a modeling exercise to
extrapolate from high to low levels of exposure.
Hazard identification, as the determination of the
relationship between the exposure to the chemical and
one or more associated adverse effects, needs a full
appraisal of information to characterize the absorption,
systemic distribution, metabolism, and elimination
(i.e., toxicokinetics) of the chemical and the toxic
effects that the chemical, or its metabolites, may have
at tissue and cellular functional levels (i.e., toxicodynamics).
Both human and animal model data are used.
Some of these are systematically acquired through
specific studies (table 1), and this applies particularly
to chemicals that are proposed as food additives. Other
data may be acquired more opportunistically, such as
from case studies and incident reports. This is more