1:
Hazardous Substances and Hazardous Waste
Chemicals affect
our everyday lives. They are used to produce almost everything we use,
from paper and plastics to medicines and food to gasoline, steel, and
electronic equipment. More than 70,000 chemicals are used regularly
around the world. Some occur naturally in the earth or atmosphere, others
are synthetic, or human-made. When we use and dispose of them properly,
they may enhance our quality of life. But when we use or dispose of
them improperly, they can have harmful effects on humans, plants, and
animals.
What is hazardous
waste?
Even when used
properly, many chemicals can still harm human health and the environment.
When these hazardous substances are thrown away, they become
hazardous waste. Hazardous waste is most often a by-product of
a manufacturing process – material left after products are made. Some
hazardous wastes come from our homes: our garbage can include such hazardous
wastes as old batteries, bug spray cans, and paint thinner. Regardless
of the source, unless we dispose of hazardous waste properly, it can
create health risks for people and damage the environment.
What kinds
of hazardous waste are there?
Most hazardous
waste is identified by one or more of its dangerous properties or characteristics:
corrosive, ignitable, reactive, or toxic.
- Corrosive
— A corrosive material can wear away (corrode) or destroy a substance.
For example, most acids are corrosives that can eat through metal,
burn skin on contact, and give off vapors that burn the eyes.
- Ignitable
— An ignitable material can burst into flames easily. It poses a fire
hazard; can irritate the skin, eyes, and lungs; and may give off harmful
vapors. Gasoline, paint, and furniture polish are ignitable.
- Reactive
— A reactive material can explode or create poisonous gas when combined
with other chemicals. For example, chlorine bleach and ammonia are
reactive and create a poisonous gas when they come into contact with
each other.
- Toxic
— Toxic materials or substances can poison people and other life.
Toxic substances can cause illness and even death if swallowed or
absorbed through the skin. Pesticides, weed killers, and many household
cleaners are toxic.
Where does
hazardous waste go?
Ideally, hazardous
waste is reused or recycled. If this is not possible, hazardous waste
is safely contained while it is stored, transported, and properly disposed
of to prevent an accidental release into the environment. Advances in
technology have greatly improved our ability to treat or dispose of
hazardous waste in a way that prevents it from harming people or the
environment. Typical methods of hazardous waste storage and disposal
include surface impoundments (storing it in lined ponds), high
temperature incineration (controlled burning), municipal and
hazardous waste landfills (burying it in the ground), and deep
well injection (pumping it into underground wells). More promising
methods focus on minimizing waste, reusing and recycling chemicals,
finding less hazardous alternatives, and using innovative treatment
technologies.
What are
the dangers of hazardous waste management?
Proper management
and control can greatly reduce the dangers of hazardous waste. There
are many rules for managing hazardous waste and preventing releases
into the environment. Even so, a lot can go wrong when we try to contain
hazardous waste. Even the most technologically advanced landfills we
build will leak some day. Tanks used for storing petroleum products
and other chemicals can leak and catch fire; underground storage tanks
weaken over time and leak their hazardous contents. Transportation accidents,
such as train crashes and overturned trucks, can occur while transporting
hazardous substances. There are also cases of intentional and illegal
dumping of hazardous waste in sewer systems, abandoned warehouses, or
ditches in remote areas to avoid the costs and rules of safe disposal.
How can hazardous
waste affect us?
When hazardous
wastes are released in the air, water, or on the land they can spread,
contaminating even more of the environment and posing greater threats
to our health. For example, when rain falls on soil at a waste site,
it can carry hazardous waste deeper into the ground and the underlying
groundwater. If a very small amount of a hazardous substance is released,
it may become diluted to the point where it will not cause injury. A
hazardous substance can cause injury or death to a person, plant, or
animal if:
- A large amount
is released at one time
- A small amount
is released many times at the same place
- The substance
does not become diluted
- The substance
is very toxic (for example, arsenic).
Coming into contact
with a substance is called an exposure. The effects of exposure
depend on:
- How the substance
is used and disposed of
- Who is exposed
to it
- The concentration,
or dose, of exposure
- How someone
is exposed
- How long or
how often someone is exposed.
Humans, plants,
and animals can be exposed to hazardous substances through inhalation,
ingestion, or dermal exposure.
- Inhalation
— we can breathe vapors from hazardous liquids or even from contaminated
water while taking a shower.
- Ingestion
— we can eat fish, fruits and vegetables, or meat that has been contaminated
through exposure to hazardous substances. Also, small children often
eat soil or household materials that may be contaminated, such as
paint chips containing lead. Probably the most common type of exposure
is drinking contaminated water.
- Dermal exposure
— a substance can come into direct contact with and be absorbed by
our skin.
Exposures can be
either acute or chronic. An acute exposure is a single exposure
to a hazardous substance for a short time. Health symptoms may appear
immediately after exposure; for example, the death of a fly when covered
with bug spray or a burn on your arm when exposed to a strong acid such
as from a leaking battery.
Chronic exposure
occurs over a much longer period of time, usually with repeated exposures
in smaller amounts. For example, people who lived near Love Canal, a
leaking hazardous waste dump, did not notice the health effects of their
chronic exposure for several years. Chronic health effects are typically
illnesses or injuries that take a long time to develop, such as cancer,
liver failure, or slowed growth and development.
One reason chronic
exposure to even tiny amounts of hazardous substances can lead to harm
is bioaccumulation. Some substances are absorbed and stay in
our bodies rather than being excreted. They accumulate and cause harm
over time.
|