Definition of a DNEL
Essentially, DNELs are new, scientifically
derived risk assessment tools similar to
OSHA PELs in the U.S. Annex One of
REACH defines the Derived No-Effect
Level (DNEL) as
the level of exposure to the substance
below which no adverse effects are expected to occur. It is therefore the level
of exposure to the substance above
which humans should not be exposed.
DNEL is a derived level of exposure because it is normally calculated on the
basis of available dose descriptors from
animal studies such as No Observed Adverse Effect Levels (NOAELs) or benchmark doses (BMDs).
The number of companies required to
calculate DNELs will grow over the next
several years. By June 1, 2013, DNELs
will be required for all chemicals manufactured or imported in excess of 100
tonnes per year; by June 1, 2018, the
threshold falls to 1 tonne per year. Once
calculated, DNELs are published in the
manufacturer’s chemical safety report for
hazard communication. The intent of
REACH is for DNELs to be added to
chemical labels.
DNELs are used in the risk characterization portion of a chemical safety assessment. They are benchmarks to
determine adequate controls for specific
exposure scenario risks. REACH specifies
that DNELs “shall reflect the likely root
duration and frequency of the exposure.”
In cases where an assessment doesn’t
have a threshold effect level—in other
words, for substances that always have
some effect at any level—REACH allows
manufacturers to determine a Derived
Minimal Effect Level (DMEL).
Implications Beyond the EU
One of the main reasons the EU devel-
oped REACH was that many substances
have been manufactured and placed on
the European market, sometimes in very
large amounts, for which insufficient in-
formation exists about the hazards they
pose to human health and the environ-
ment.1 Some concerns have been related
to toxins in toys and polybrominated
diphenyl ethers (PBDEs) in breast milk,
for example, where the routes for expo-
sure weren’t well defined in some cases
for sensitive populations. REACH ad-
dresses many of these concerns by as-
suming that all chemicals are unsafe un-
less proven otherwise. The process to ob-
tain environmental and human effects
data on exposure to chemicals, once
thought in the EU to be broken, is now
considered fixed.
Developing a successful
DNEL requires manufacturers
or importers of chemicals
to provide a valid study.
The EU determined that
the costs of registering
chemicals and developing
exposure assessments
would be offset by decreased
health-care costs associated
with exposures.
Developing a successful DNEL requires manufacturers or importers of
chemicals to provide a valid study. The
EU determined that the costs of registering chemicals and developing exposure
assessments would be offset by decreased health-care costs associated with
exposures. If more than one company
manufactures or imports a particular
Coming Soon: DNELs | FEATURE
chemical, the companies are required to
collaborate prior to the chemical’s registration deadline. The REACH regulation
estimates that, by the end of 2018, tens
of thousands of new DNELs and other
exposure limits will be generated.
Ultimately, DNELs will be listed on
safety data sheets with other exposure
limits. In the EU, the DNEL process may
eventually replace some current occupational exposure limit processes; some
countries are already using it as a default (unless the government believes
lower limits are justified).
Some evidence exists that acceptance
of DNELs, or similar limits, is inching its
way into the U.S. and other countries.
The Safe Chemicals Act of 2010, introduced in April by Senator Frank Lauten-berg, implies a REACH-like approach to
chemical manufacturers. The Safe Chemicals Act is intended to be a means for
developing new exposure limits.
Whether this bill will get off the floor remains to be seen. But if it passes, manufacturers will have to derive an
assessment and permissible exposure
level in the U.S., and the OEHS industry
will see a flurry of activity to meet this
requirement.
As hundreds and possibly thousands
of DNELs are developed and published,
IH and OEHS professionals will have an
obligation to consider these new limits in
their effort to protect workers. It would
be inappropriate to ignore a standard
such as a DNEL during a risk assessment.
Eventually, the DNEL may very well become a de facto PEL in the U.S. for thousands of chemicals that have never been
associated with a specific exposure level.
Questions about Methods
The spread of DNELs has the potential to
require development of new methods of
data collection and exposure monitoring.
In practice, one doesn’t always know
whether a compound can be effectively
collected and quantitatively analyzed if
no validation study has been performed
on the method. Validation studies are
exhaustive studies used to show how a
compound can be accurately and precisely collected and quantitatively analyzed under varying conditions,
including temperature, humidity, light
and time. OSHA and NIOSH have performed validation studies on a few hundred compounds, but very few have been
