Overview
TCAS has extensive experience assessing environmental hazards[a]
Environmental hazards are substances found within a confined environment which can
pose an exposure hazard if ingested, inhaled or absorbed. These include such agents
as dust, mold and fungi, carbon monoxide, pyrolysis emissions, nuclear
waste and many others. The wide range of environmental hazards and scope of health effects
means the scientific credibility of a toxicological assessment will largely be determined by
strict adherence to generally-accepted, peer-reviewed investigative methods.
It is not possible to present a comprehensive overview of environmental hazards
in this brief section. The substances presented herein are toxic agents for which
TCAS has regularly performed dose-response assessments, evaluated
potential health impacts and environmental consequences, collected air, water and soil samples, performed
laboratory analyses, monitored ambient concentrations, investigated
source, fate and transport issues, produced written reports
and/or offered expert testimony in litigation.
Click on any substance to view the corresponding entry.
Click to view other types of hazardous substances.
Carbon Monoxide (CO)
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Carbon Monoxide[b]
Carbon monoxide (CO) is an odorless, colorless toxic gas which is impossible to
smell, taste, or see. Carbon monoxide poisoning is fatal at high concentrations.
At lower levels, CO can cause headaches, nausea, fatigue, dizziness, disorientation
and many other adverse health effects. CO is frequently found in indoor air as a
result of incomplete combustion. Common carbon monoxide poisoning emission sources
include unvented kerosene and gas space heaters, leaking chimneys and furnaces,
stoves, portable generators (as documented in
a recent
TCAS case study), automobile exhaust and many others1.
Carbon monoxide causes the formation of carboxyhemoglobin (HbCO) in the
blood which inhibits oxygen intake. Symptoms are heavily influenced by dose, duration
of exposure, age, health, environmental factors and other variables. Acute effects
can include angina, impaired vision, reduced brain function and neurological effects.
Chronic effects can include damage to the heart and respiratory system, disruption
of the central nervous system, a variety of pathological conditions and ultimately,
death. Carbon monoxide can also adversely affect an unborn fetus.1
TCAS has performed numerous carbon monoxide toxicological exposure assessments
and has produced written reports and/or provided expert testimony subsequent to
being retained by defendants, plaintiffs, prosecutors, public defenders' offices
and U.S. attorney generals' offices. In some instances, TCAS personnel visited
exposure sites and re-created the actual conditions under which CO exposures occurred to
validate assessment opinions. Please
contact our office for additional information.
Dust Toxicity
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Magnified dust particle[c]
The electron microscope photo at left shows a single dust grain magnified by a factor
of 100,000. U.S. EPA defines dust as "…solid particles generated by
any mechanical processing of materials including crushing, grinding, rapid impact,
handling, detonation and decrepitation of organic and inorganic materials such as
rock, ore and metal."2 Thus, airborne
substances (whether consisting of or carried by "dust" particles) have
measurable toxicological properties which can be assessed in a health context. For
example, some dust contaminants are potentially toxic, with prolonged exposure resulting
in any of a variety of adverse health effects. Conversely, some dust contaminants
may carry comparably lower health risks but can, nevertheless, cause severe nuisance
effects (such as aggravation of asthma, eye irritation, bronchial congestion, etc.).
Depending on the contaminant, direct contact with skin or mucous membranes can also
produce measurable toxicological effects. Particle size, composition, contaminant
concentration (as measured in µg/m3) and deposition
patterns are all important components in a toxicological dust assessment. Residential
dust samples are frequently collected over time at exposure sites to help chart
and assess the dose of an alleged toxic release. Airborne distribution and deposition
patterns (called "isopleths") can also be useful for documenting the extent
of contamination. TCAS has extensive experience in toxicologically assessing
dust exposures and remediation issues in residential, environmental and industrial
cases in both causative and risk assessment scenarios. Please contact our
office for additional information.
Mold and Fungi
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Mold growing under carpet[d]
Although molds are part of our natural environment, indoor mold growth can cause
significant adverse health effects. Molds produce allergens (substances that can
cause allergic reactions) as well as potentially toxic substances called mycotoxins.
Inhaling or touching mold or mold spores can cause allergic reactions in sensitive
individuals. Allergic responses include hay fever-type symptoms such as sneezing,
runny nose, red eyes, and skin rash (dermatitis). Molds can also cause asthma attacks
and eye irritation as well as skin, nose, throat and lung irritation in both mold-allergic
and non-allergic people. More severe reactions may occur among individuals frequently
exposed to molds in confined spaces. People with chronic lung illnesses may develop
mold infections in their lungs. For example, the photo at left showing mold growing
on wet plywood under a carpet in a recreational vehicle was sufficiently severe
to cause Aspergillus spores to be inhaled and start to grow in the occupant's
lungs (as documented in
a recent TCAS case study).
U.S. EPA3
stresses the importance of moisture reduction to control mold growth; e.g. "There are many
types of mold and none of them will grow without water or moisture."
A seminal toxicological study4 written in 1966 by
Gerald N. Wogan ("Chemical Nature and Biological Effects of the Aflatoxins")
documented the presence of mold contaminants with a high order of toxicity in animal
feeds. These molds were also shown to possess potent carcinogenic properties in several
animal species. TCAS has conducted numerous risk assessments involving
mold contamination and provided expert testimony on behalf of both plaintiffs and
defendants. Please
contact our office for additional information.
Pyrolysis Emissions
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Pyrolysis chamber[e]
Pyrolysis is a complex subject touching on many aspects of toxicology. Pyrolysis
refers to the thermochemical decomposition of organic material in the absence of
oxygen at temperatures typically above 800° F.5
Pyrolysis is widely applied as an industrial manufacturing process to transform
medium-weight hydrocarbons from oil into lighter ones (such as gasoline). It is also
used to manufacture polyvinyl chloride (PVC) and other materials.
Although pyrolysis has recently been touted as a "green" alternative to
waste incineration, it is extremely difficult in practice to achieve a completely
oxygen-free atmosphere. Thus, a small amount of oxidation almost always occurs.
If volatile or semi-volatile materials are present in the waste, many of the same
toxic by-products produced by traditional incinerators can be released including
dioxins and furans, mercury, carbon monoxide, hydrogen chloride, sulfur dioxide
and many other toxic compounds. Toxic gases can also be produced as well as toxic
contaminants in the char & ash residues or in contaminated waste water. Secondary
treatments can remove some of the toxic substances, but disposal of these components
can also be problematic. In particular, systems treating hazardous wastes containing
polychlorinated biphenyls (PCBs) have the potential to create products of incomplete
combustion, including dioxins and furans which can be highly toxic in the parts
per trillion range. Additionally, condensed liquids from cooled off-gases can produce
an oil/tar residue which can contaminate both soil and water.6
Some pyrolysis contaminants are carcinogenic at very low exposure levels and humans
and/or animals exposed to pyrolysis waste products can experience a wide range of adverse
health effects. TCAS has conducted toxicological risk assessments involving
pyrolysis emissions, toxic releases and contamination and disposal of waste materials.
TCAS has also investigated source, fate and transport issues, performed
dose-response assessments and provided expert testimony on behalf of both plaintiffs
and defendants. Please
contact our office for additional information.
Radioactive Waste
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Universal symbol for radioactivity[f]
Radioactive waste is hazardous to most forms of life and is tightly regulated by
government agencies to protect human health and the environment. The term "radioactive
waste" refers to any waste product containing radioactive material, but there
are many types of radioactive waste beyond the high-level radioactive substances
typically associated with nuclear power plants. For example, tailings from mining
operations in regions rich in uranium can produce both solid and liquid radioactive
waste. Such waste can be extremely toxic if allowed to infiltrate into residential
areas (as fugitive dust) and/or municipal water supplies. Radioactive wastes which
are both radioactive and chemically hazardous are regulated jointly by the U.S.
EPA, the Nuclear Regulatory Commission (NRC) and the Department of Energy (DOE).
Radioactive materials decay spontaneously to produce ionizing radiation. Any living
tissue in the human body can be damaged by such radiation — the most common
forms being alpha and beta particles. Higher intensity radiation includes gamma
and X-rays. Cancer is the primary health effect from radiation exposure, but other
health effects can also occur. Radiation can cause damage to the body's DNA, the
"blueprint" that ensures cells produce perfect copies of themselves. Sometimes
the body fails to repair damaged cells (called mutations) or may even create new
mutations during repair. Mutations can be teratogenic (affecting only the fetus
in the uterus of the exposed individual) or genetic (passed on to future offspring).
The primary exposure route for the general population is via ingestion of food and
drinking water. Only about 1% of ingested uranium will enter a person's blood.7 Most of this is removed by the kidneys and excreted
within a few days. A small amount of the uranium will deposit in the bones. Intakes
of uranium exceeding U.S. EPA standards can lead to increased cancer risk, liver
damage or both. Other potential targets of toxicity include the reproductive system
and the developing organism. Long-term chronic intakes of uranium isotopes in food,
water or air can lead to internal irradiation and/or chemical toxicity. The toxicity
of uranium is mainly due to chemical damage to the kidneys or respiratory tract,
with adverse effect levels varying depending on the particular uranium compound
and its solubility.8 Absorption of uranium is low
by all exposure routes (inhalation, oral, and dermal). The deposition of inhalable
uranium dust particles into the lungs depends on the particle size, whereas absorption
depends on its solubility in biological fluids (ICRP 1994a, 1996). A final toxicological
profile for uranium was produced in April, 2013, by ATSDR in which minimum risk
levels (MRLs) were established for uranium exposure by both oral and respiratory
routes.9 TCAS has conducted numerous risk
assessments involving radioactive materials and provided expert testimony on behalf
of both plaintiffs and defendants. In some cases, we have visited release sites,
collected samples for laboratory analyses, produced objective documentation with
respect to scope and severity of contamination and provided remediation guidance.
Please
contact our office for additional information.
Notes and References
- U.S. Environmental Protection Agency, "Introduction to Indoor Air Quality: Carbon Monoxide (CO)," EPA 404/F-08/008, September, 2008.
- U.S. Environmental Protection Agency, "What is a fume or dust?," EPA No. 23002-22031, 10/25/2006.
- U.S. Environmental Protection Agency, "Mold Resources," EPA No. 402-K-02-003, September 2010.
- Wogan, Gerald N., "Chemical Nature and Biological Effects of the Aflatoxins," Bacteriological Reviews, June, 1966, American Society for Microbiology.
- Moldoveanu, S., "Pyrolysis of Organic Molecules: Applications to Health and Environmental Issues," Elsevier, Sep, 2009.
- Soesilo, J. Andy & Wilson, Stephanie, "Site Remediation: Planning and Management," January, 1997, 9781566702072.
- National Center for Biotechnology Information, "Background and Environmental Exposures to Uranium in the U.S.," National Library of Medicine, 2011.
- U.S. Environmental Protection Agency, "Uranium," October, 2012.
- ATSDR, Division of Toxicology and Environmental Medicine, "Toxicological Profile for Uranium," February, 2013.
Images
- Montage of public domain thumbnail images: OSHA, U.S. EPA, NASA, National Park Service, Missouri Department of Natural Resources, et al.
- U.S. EPA, Carbon Monoxide.
- Magnified dust particle: NASA, Minor Objects in the Solar System.
- Photo by TCAS © Copyright 2017, adapted from case report
- Pyrolysis of Organic Molecules, "Applications to Health and Environmental Issues"
- National Park Service, Radioactivity