Environmental Health and Toxicology

EB

Lecture 10

2008 Spring

• 1.Describe some environmental hazards that you think you may be living with indoors. How do you think you may have been affected by indoor or outdoor environmental hazards in the past? What philosophical approach do you plan to take in dealing with these toxicants in your own life?

• 2.Why is it that research on endocrine disruption has spurred so much debate? What steps do you think could be taken to help establish more consensus among scientists, industry, regulators, policymakers, and the public?

• 3.Do you feel that laboratory-bred animals should be used in experiments in toxicology? Why or why not?

• 4.Describe differences in the policies of the United States and the European Union toward the study and management of the risks of synthetic chemicals. Which do you believe is better, the policies of the United States or the European Union, and why?

• 5. You are the parent of two young children, and you want to minimize the environmental health risks to your family as your kids grow up. Name five steps that you could take in your household and in your daily life that would reduce your children's exposure to environmental health hazards.

• 6. You have just been hired as the office manager for a high-tech startup company that employs bright and motivated young people but is located in an old, dilapidated building. Despite their youth and vigor, the company's employees seem perpetually sick with colds, headaches, respiratory ailments, and other unexplained illnesses. Looking into the building's history, you discover that the water pipes and ventilation system are many decades old, that there have been repeated termite infestations, and that part of the building was remodeled just before your company moved in but there are no records of what was done in the remodel. Your company has all the latest furniture, computers, and other electronics. Most windows are sealed shut. There is an indoor smoking lounge.

What shall I learn?

• Identify the major types of environmental health hazards and explain the goals of environmental health

• Describe the types, abundance, distribution, and movement of toxicants in the environment

• Discuss the study of hazards and their effects, including case histories, epidemiology, animal testing, and dose-response analysis

• Assess risk assessment and risk managementCompare philosophical approaches to risk

• Describe policy and regulation in the United States and internationally

Case study

• Alligators and Endocrine Disruptors at Lake Apopka, Florida

Case Study - Florida Lake

• 1985 scientists noticed a strange defect in alligators

• Their reproductive biology was weird• Fewer eggs were viable

– Male babies were ‘Cross-dressers’– Females were extremely feminine– Both had defective reproductive structures

• WHY?

Case Study - DDT

• Finally concluded that dicofol and DDT were causing the defects

• The lake was receiving lots of farm runoff

• These chemicals were interfering with the developmental biology of these animals

• ENDOCRINE DISRUPTORS– Mimic estrogen - the female sex hormone

Case Study - Atrazine

• Other lake systems also began to show similar biology

• Found a herbicide called atrazine which converts stuff to estrogen.

• Nitrate from fertilizer also acts as an endocrine disruptor

• COULD THE SAME BE HAPPENING TO YOU!!!!!!!!!

Environmental Health

• - Exams impacts of human-made chemicals on wildlife and people

• Both natural factors, and

• Man-made factors

• Contribute to this field of study

• Environmental Health Officials seek to understand and then minimize effects.

Types of Environmental Hazards

• Physical

• Chemical

• Biological

• Cultural

Physical hazards

• Your choice…– Earthquakes– Volcanic eruptions– Fires– Floods– Blizzards– Landslides– Hurricanes– Droughts– Ultraviolet (UV) radiation

Preventing Physical hazards

• We can use technology and natural patterns to minimize the effects of these events.

• Some we can address• others are beyond our control (currently)

• We know many of our practices are INCREASING the risks…

Chemical Hazards

• Natural and Man-made chemicals

• Natural– Bee stings

• Man-made– Bleach– Shampoo– Alligator type chemicals

Biological Hazards• Interaction with other living organisms• Bacterial, viruses, fungi, parasites,

insects, etc.

• Cannot stop entirely

• Can take preventive measures to reduce impact

Cultural Hazards

• Simply from the place we live• Our occupation• Your economic status• Your social status• Choices

– Smoking– Drugs– Drinking, etc.

Disease is a killer

• One of the major factors

• We seem to be going backwards with this one…. Losing ground.

• More people will die of this than anything else in the near future, and it appears to be taking a greater toll…

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By category and within category

Disparity

• Nearly half these deaths are in developing countries are form disease

• Just just a few in developed countries

• WHY?

• Hygiene

• Medicine– Tied to The Wealth factor

However things are changing

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West Nile

Climate change

• Evolution is a great enemy…

• So is global warming…

• And globalization…

• Habitat alteration too…

JOB Description…

• Environ. Health experts

• Job is to predict & prevent disease

• They study EB and try to elicit the relationship between disease and cause

Your home is your CASTLE. No death trap

• We associate hazards to outside our home

• Sorry….

• We spend at least 8 hours or so inside our homes each day

• There are many hazards there too…

Gas me to death

• Radon is a deadly invader

• In some parts of the country this gas traps inside our homes

• It is radioactive.

• Lung cancer

• 1 in 1000 may have cancer

I want more toys from China

• Lead poisoning leads to organ damage– Paint, water pipes, solder– 1 in 6 under 6 years of age

• Asbestos– Inhaled danger– Lung cancer

• PBDEs– Computer and electronics– Accumulate over time

JOB - Toxicologist

• the science that examines the effects of poisonous substances on humans and other organisms

• Toxicologists assess and compare substances to determine their toxicity, – the degree of harm a chemical substance

can inflict.

• A toxic agent is referred to as a toxicant

Facts

• During the past century1. our ability to produce new chemicals has

expanded

2. concentrations of chemical contaminants in the environment have increased, and

3. public concern for health and the environment have grown.

New field has emerged• environmental toxicology,

– which deals specifically with toxic substances that come from or are discharged into the environment.

• Environmental toxicology includes the study of health effects

• on humans• other animals, and • ecosystems,

– and it represents one approach within the broader scope of environmental health.

Live with it or loath it

• These same chemicals which we detest gave us what we have as a society today.

• Agriculture

• Medicines

• Modern conveniences

Toxins in the Environemnt

• Many in the environment

• Natural– Oil– Radon– Toxins in plants

• Synthetic– Man-made chemicals

Outside in

• Most chemicals we use have found their way inside our bodies

• Not all are toxicants• However, just a few of the 100,000s

have been completely tested before deployment.

• Many people use them without second thought…

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SILENT SPRING

• Rachel Carson

• 1962

• DTT - pesticide

• The power of the Ad…..

A cup of toxicant please• Sir would you like that as;

1. Carcinogen1. Know to cause cancer

2. Mutagen1. Cause mutation in DNA

3. Teratogen1. Effect development of the embryo

4. Neurotoxins1. Assault the nervous system

5. Allergens1. Hyper response from immune system

6. Endocrine disruptors1. Interfere with the hormone system

Toxicants in water

• Everything seems to empty out in some water runoff.

• So frogs and other aquatic animals are good indicators of pollution.

• Frogs species are declining.

• What does this tell us????

Toxicants can fly

• Air currents may carry the chemicals to new destinations.

• Found in the most remote places– Antarctic– Artic– Amazon

Forever my toxicant

• They persist for very long times

• They were designed to persist

• Plastics resist breakdown

• DDT breaks down to DDE, also highly toxic and persistent.

I never ordered that!

• The food chain can carry toxicants to you indirectly

• Mercury in fish

• DDT in coffee

• Biomagnification - evident in birds of prey, and all other top predators

How do we study the hazards?

Observations

• What killed sea otters - the cats did!

• A protist called toxoplasma

• Feces of cats enters sewage runoff into ocean

• Kills otters

Sherlock Holmes

• We play detective with each new unexplained disease and we work backwards to discover the history

• Epidemiological studies on large populations reveal patterns.– Lead to discovery of cause– Long lead time– Only on past situations

LD50

• Main method is LD50 analysis

• Testing on lab animals for negative effects

• How much to cause half of the animals to die or show effect.

• ED50 - effective dose

We are all different

• Responses are not identical for all tested subjects

• Variation exist - I can withstand more toxin than you!

• EPA is using a flawed system to protect the young and the light.

Quick and fast, or long and slow

• Acute exposure– High exposure over little time

• Chronic exposure– Less but over longer times– Harder to detect and measure

Who decides?

• FACT• Policy and management decisions

reach beyond the scientific results on health to incorporate considerations about economics and ethics.

• And all too often, they are influenced by political pressure from powerful interests - the special interests

Will it or won’t it!

• Exposure predicts probability of effect

• Risk analysis is weighed to determine the need to deploy that susbtance

Risk it!

• People often worry unduly about negligibly small risks but happily engage in other activities that pose high risks.

• For instance, most people perceive flying in an airplane as a riskier activity than driving a car, but driving a car is statistically far more dangerous…

Risk it too

• The threat of another terrorist attack is much smaller than your child being killed on the way to school by a drunk driver…

• Do we bomb and attack drunks?• The above example is for illustration purposes only.

Control

• Things outside our control scare us.

• We are much more tolerant of things that we can control.

• Risk assessment is complex

• Risk management involves social parameters as well as scientific ones.

Rush it to me!

• Two approaches to introduce new substances to market

• 1) limited testing and then market

• 2) Extensive testing then market

• Manufactures needs to prove safety

• Government needs to prove danger

Europe vs USA

• Europe is adopting the cautionary approach

• US is not!!!!

• I think this tells you who is running the country!!

• THE CORPORATIONS

• And you WILL suffer in the long term.

EPA

• Tasked with regulating pesticides• Now a political force under the Bush

administration• Making decisions that do not seem

logical by all standards, even US!• EUROPE leads once again in

implementation - we all need to move there!

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