In response to concerns about the recent chromium trioxide spill
in the Evergreen Park subdivision, the New Brunswick Departments
of Environment and Health have prepared the following Frequently
Asked Questions guide to some of the main questions surrounding
the spill and its potential impacts.
Chromium is a naturally occurring element that is found in small amounts
in soil and rock. Low levels of chromium are often seen in analysis
of groundwater and drinking water. When chromium is found naturally
in well water it is typically at a level of micrograms (millionths
of a gram) of chromium per litre of water. Micrograms per litre are
also called parts per billion.
Most people are familiar with chromium metal, which gives the bright
silvery shine to chrome-plated products, but in nature chromium exists
in a variety of chemical compounds rather than as the metal.
2. What is hexavalent chromium?
Why is it a concern?
Hexavalent chromium refers to one possible class of chemical compounds
that contain chromium. This class includes chromium trioxide, chromic
acid and various chromate and dichromate salts. Hexavalent chromium
compounds are in general much more toxic than other compounds of chromium,
and they can be very reactive chemicals as well (strong oxidizers).
Hexavalent chromium compounds are extraordinarily rare in nature,
so exposure to hexavalent chromium usually only results from industrial
chemicals. Exposure to hexavalent chromium at levels above 0.05 mg/L
in drinking water may cause diarrhea, vomiting, abdominal pain, indigestion,
convulsions, and liver and kidney damage. The risk to human health
is through ingestion which includes drinking, cooking and teeth brushing.
Short term exposure to a high concentration of hexavalent chromium
can cause irritation or burns to the skin, eye, mouth, nose, stomach
or lungs depending on the concentration and whether a person is exposed
through breathing, ingesting or coming into direct skin contact with
hexavalent chromium. Long term exposure to a lower concentration but
still above the New Brunswick Health Advisory may result in malfunction
of the kidneys or liver or cancer of various organs such as stomach
cancer if ingested or lung cancer if inhaled. If exposure is mainly
to contaminated air ulcers or holes in the tissues of the nose or
inflammation of the respiratory passages may occur.
Persons with pre-existing skin disorders, asthma, allergies or known
sensitization to chromic acid or chromates may be more susceptible
to the effects of this material.
Data on risk to human health is available from studies on cells, experiments
on animals, and from studies of industry workers having been exposed
to fairly high concentrations. Therefore, the information provided
above may overstate the risk to people exposed to significantly lower
concentrations.
3. Are there regulatory
limits to how much chromium in water is too much?
The New Brunswick Health Advisory Level (HAL) for chromium in drinking
water is 0.05 mg/L (milligrams per litre), which is equivalent to
50 micrograms per litre. Levels below this are considered safe for
human health. The New Brunswick HAL is based on the Guidelines for
Canadian Drinking Water Quality published by Health Canada.
Some examples of chromium limits in drinking water from other jurisdictions
around the world include the US National Primary Drinking Water Standard
of 0.100 mg/L (equivalent to 100 micrograms per litre), the World
Health Organization guideline (0.05 mg/L, equivalent to 50 micrograms
per litre) and the European Union standard (50 micrograms per litre).
Note that although hexavalent chromium compounds are the most toxic
form of chromium, regulations around the world are generally based
on total chromium regardless of which chemical form it occurs in.
However, these regulatory limits were all derived based on a worst-case
scenario (i.e. if all chromium were hexavalent) so they are considered
protective for hexavalent chromium exposure even when only total chromium
is tested, as is typically the case in drinking water chemistry testing.
4. How much chromium is
typically present in well water in New Brunswick?
The New Brunswick Department of Environment has determined that about
one-third of well water samples in New Brunswick typically contain
some detectable level of total chromium. About 4% of all well water
samples contain chromium at 25 micrograms per litre or more, but levels
above the New Brunswick HAL (50 micrograms per litre) are quite rare
(less than 0.2% of all cases). These observations are based on an
analysis of over 10,000 private well samples tested under the Potable
Water Regulation, Clean Water Act.
5. Why is the recent spill
in Evergreen Park a concern?
The recent spill contained a large amount of chromium trioxide (also
called chromic acid when dissolved in water). This industrial chemical
is a hexavalent chromium compound, is a reactive chemical (strong
oxidizer) and water solutions of it are strongly acidic.
Concentrations of chromium in the solutions that were spilled are
at the level of grams per litre (i.e. nearly a million times more
concentrated than acceptable levels in drinking water) so they pose
a very serious potential hazard to groundwater quality in the vicinity.
6. Why was the recent Department
of Health advisory a “no contact with water” advisory?
This advisory was issued because of the nature of the chemical involved
and the high initial concentration.
It is the mandate of the Department of Health to advise the public
if they are at risk of exposure to a contaminant that may cause adverse
health effects. In this situation, the Department of Health feels
it is necessary to advise individuals who may be exposed to chromium
through their drinking water wells so they can take appropriate actions
to reduce any potential exposure.
7. What is being done at
the impact site?
The Department has retained a Site Professional to assess and remediate
the site. Environmental work associated with the remediation of the
source site to date includes the removal of chromium product, installation
of boreholes and monitoring wells, excavation of test pits and a soil/groundwater
sampling program. This work will determine the degree and extent of
the impacts and how far the contamination has migrated from the spill
area as well as long term remedial measures. All work is being conducted
in accordance with the current version of the Guideline for the Management
of Contaminated Sites. The objectives of the site remediation are
to protect the environment and human health.
The Departments of Health and Environment are currently monitoring
private wells in proximity to the spill for any potential changes
in chromium levels. Sampling results indicate that all levels of chromium
detected are below the Guideline for Canadian Drinking Water Quality
/ Health Canada value of 0.05 mg/L.
The Site Professional has overseen the removal of chromium contamination
present in the ground by pumping contaminated groundwater and removing
it from the site in tanker trucks for proper disposal. The septic
tank has also been emptied to remove a significant portion of the
spilled chromium product.
Efforts are on-going to further assess and clean up the site. The
Site Professional will propose longer term remedial actions once the
site has been thoroughly assessed.
8. How long will it be
before the situation is resolved?
From a remediation perspective, a timeline for site clean-up cannot
be estimated at this time. Site assessment and data collection are
still ongoing. Once additional site assessment information is available,
the Site Professional will be in a better position to recommend a
Remedial Action Plan (RAP - actions required to achieve applicable
environmental criteria). A requirement of the RAP is to present an
estimated timeline for completion of the Management Process (i.e.
site closure).
9. Where can I find further
information?
For questions relating to the health effects of chromium, please contact
the Department of Health at (506) 458-2830.
For information regarding environmental issues please contact the
Department of Environment Fredericton Regional office at (506) 444-5149.
