Chapter 17 - Environmental Hazards and Human Health

Risk assesment

Risk assesment

involves identifying hazards and evaluating their associated risks

comparative risk analysis

ranking risks

risk management

determining option and making decisions about reducing or eliminating risks

risk communication

informing decision makers and the public about risks

Risk

the possibility of suffering harm from a hazard that can cause injury, disease, economic loss, or environmental damage.

Risk is expressed in terms of

Probability

Major types of hazards

cultural, chemical, physical, biological

Cultural hazards

poor diet, drugs, driving, assault

Chemical hazards

harmful chemicals in the air, water, soil and food

Physical hazards

fire, weather, radiation

Biological hazards

pathogens, allergens and animals

toxic chemical

is one that can cause temporary or permanent harm or death

Hazardous chemicals are

• Flammable or explosive

• Irritating or damaging to the skin or lungs

• Interfering with oxygen uptake

• Inducing allergic reactions

Mutagens

cause random mutations in DNA

Carcinogens

promote growth of malignant tumors

One major problem with some chemical hazards

particularly heavy metals and persistent organic pollutants (POPs) is bioaccumulation and biomagnification

Bioaccumulation

is an increase in the concentration of a chemical in specific organs or tissues over time

Biomagnification

is an increase in concentration of chemicals in organisms at successively higher trophic levels

Minamata Disease

is not a disease but refers to the neurological effects from mercury poisoning.  It was first discovered in 1956 in Minamata, Japan, where methyl mercury from industrial wastewater bioaccumulated in the fish and shellfish that people ate

The median lethal dose (LD50)

is the amount of chemical received in one dose that kills exactly 50% of the subjects in a test population

A poison

is a chemical that has an LD50 of 50 mg or less per kilogram of body weight

The threshold level of toxicity

is the dose below which no toxic effects are observed and/or above which the toxic effects are apparent

Physical Hazard 1

Earthquakes resulting in loss of life and property

Physical Hazard 2

Volcanoes resulting in loss of life and property

Physical Hazard 3

Ionizing Radiation in the form of X-rays, radiation from nuclear sources, and UV radiation from the sun or sun lamps

Nontransmissible diseases

are not caused by living organisms and do not from one person to another

examples of nontransmissible diseases

diabetes, bronchitis, malnutrition, mesothelioma

transmissible diseases

are caused by living organisms and can be spread from one person to another.  The infectious agent is called a pathogen.

examples of transmissible diseases

tuberculosis, HIV, West Nile, cholera, malaria, dysentery, SARS, MERS, COVID

Number of Deaths Worldwide per year (in millions)

• 3.2 - Pneumonia and Flue

• 2.1 – HIV/AIDS

• 1.9 – Diarrheal diseases

• 1.7 – Tuberculosis

• 1.0 – Malaria

• 1.0 – Hepatitis B

• 0.8 - Measles

The Zika virus

first identified in Africa in 1947, is spread primarily through mosquitoes. ___ can cause birth defects and has no cure, though only one in five infected people die. It has been spreading faster in recent years, with a notable outbreak in 2016, in part due to warming global temperature.

Ebola

has killed one person in the U.S. and that person had just returned from Liberia where he contracted the disease.  In comparison, an American dies every 33 seconds from Heart Disease.

Worst Ebola Outbreak

In 2014, about 5,000 died, mostly in West Africa

CoronaVirus (COVID-19)

originated from a live animal market in Wuhan, China in December of 2019 and was declared an outbreak of international concern by the World Heath Organization by January of 2020. Spreading very easily, COVID-19 has infected more than 761 million people, killing more than 1.14 in the U.S. and 6.8 million Worldwide (as of 03/2023).

Leading Causes of Death in the US (CDC 2017)

#1 – heart disease #6 – Alzheimer’s disease

#2 – cancer #7 - diabetes

#3 – accidents (falls/vehicles) #8 – influenza & pneumonia

#4 – respiratory disease #9 – kidney disease

#5 – stroke #10 - suicide

As a country industrializes, it usually makes an epidemiological transition (ET)

where chronic diseases overtake childhood infectious diseases in mortality

ET Phase 1

is characterized by extremely high death rates with peaks due to epidemics, famines, and wars

ET Phase 2

is characterized by less frequent epidemic peaks and a dropping death rate due to medical advances

ET Phase 3

Phase three is characterized by a leveling off of death rate with most death occurring from nontransmissible diseases associated with aging

ET Phase 4

continues with a level death rate and shows an increasing average life span due to medical advances

ET Phase 5

shows an increase in death rate due to the reemergence of new infectious diseases due to urbanization and the overuse of antibiotics and pesticides