Toxicology & Public HealthIn 399 B.C. Socrates was accused of "impiety", of "neglect of the Gods whom the city worships and the practise of religious

novelties" and of the "corruption of the young".Friends were willing to arrange for his escape Socrates, in deference to the rule of law, he took the poison Hemlock in

prison.

Jacque-Louis David

Cicuta maculata Cicutoxin

• On October 5, 1992, a 23-year-old man and his 39-year-old brother were foraging for wild ginseng in the midcoastal Maine woods. The younger man collected several plants growing in a swampy area and – Younger one took three bites from the root of one plant. His brother took

one bite of the same root. Within 30 minutes, the younger man vomited and began to have convulsions; they walked out of the woods, and approximately 30 minutes after the younger man became ill, they were able to telephone for emergency rescue services. He died approximately 3 hours after ingesting the root.

– Although the older brother was asymptomatic when he arrived at the emergency department, he was treated. He began to have seizures and exhibit delirium 2 hours after eating the root; he was stabilized and transferred to a tertiary-care center for observation. No additional adverse effects were reported.

• The root ingested by the two brothers was identified as water hemlock (Cicuta maculata). Cicutoxin, a poisonous substance in water hemlock is the suspected killer

• What are toxic substances?

• How do we know they are toxic?

• What do we do to manage toxic substances?

Toxicity

• Negative effect of a chemical on the health of people and animals– Cancer effects (Carcinogen)

• Leukemias, tumors

– Noncancer effects • immune function, • allergies, • mutagenic, • hormone system

Dose/Response

• The dose = the poison

Any chemical can be toxic at some dose

Dose/Response

• In the lab chemicals are given to test animals at higher levels than are typically in the environment– From different doses a curve is drawn & the amount

that would kill 50% of the study animals is the LD50– ED50 is the level at which 50% of the population is

affected

NOEL – no observed Effect level

LD 50 – lethal dose 50%

ED 50 – effective dose 50%

Precautionary PrincipleA 1998 consensus statement:

"when an activity raises threats of harm to human health or the environment, precautionary measures should be taken even

if some cause and effect relationships are not fully established scientifically"

Four central components:

1. taking preventive action in the face of uncertainty;

2. shifting the burden of proof to the proponents of an activity;

3. exploring a wide range of alternatives to possibly harmful actions; and

4. increasing public participation in decision making.

Innocent until guilty

• Testing for toxicity is a long, long process

• One approach is to put substances out without exhaustive testing

• Benefits advancement of new technologies

• Downside is some things may be more harmful than originally thought.

Studying Toxins - Mercury• Mercury in the environment from dental

work, manufacturing, also used in pesticide formulations in the past

• Methylmercury formed by bacteria• CH3Hg+ U.S. Environmental Protection Agency,

1997

During the last 150 years, human activities have more than doubled natural amounts of mercury in the atmosphere

Source categories

– municipal and medical waste incineration (25% each);

– utility boilers (21%); – commercial/industrial boilers (12%) and (2). – Natural sources: volcanic emissions, degassing from

soils, and volatilization from the ocean.

USEPA Mercury Study Report to Congress, http://www.epa.gov/ttn/oarpg/t3/reports/volume3.pdf

Studying Toxins - CH3Hg+

• Methyl Mercury is the form that is highly toxic and easily assimilated in the body– Transported in red blood cells – Readily penetrates membranes

resulting in widespread distribution in the body

Studying Toxins - CH3Hg+

– Central Nervous System is the target organ. • In the CNS, methyl

mercury remains in the organic form but in other tissues is converted and stored as inorganic mercury

Studying Toxins - CH3Hg+

• LD50 values for various rodent species

range from 21 to 57.6 mg/kg

• Blood mercury level of 200 µg/mL, is a level associated with minimal health effects in humans

(mg = 0.001 L)

Studying Toxins - CH3Hg+

• Contaminated grain- Iraqi flour epidemic– Most severely affected infants had mercury

blood levels ranging from 319 to 422 µg mercury/dL. (dL = 0.1 liter & ug = 1E-06)

– 45% infant mortality rate was reported for pregnant women with signs of mercury poisoning versus a 7% mortality rate for the general population.

Studying Toxins - CH3Hg+

• Rats-changes in liver structure

• Mice-behavioral changes, some tumor development

• Monkeys- visual effects at low doses, decreases in pregnancy & increase in lost pregnancies

• Accumulates in fish tissue

http://risk.lsd.ornl.gov/tox/profiles/methyl_mercury_f_V1.shtml#tehttp://www.atsdr.cdc.gov/toxprofiles/tp46-c2.pdf

Aquatic Studies of the environment

where ocean-derived salts measure less than 0.5 ‰ during the period of average annual low flow

http://www.fcsc.usgs.gov/posters/Ecotoxicology/Mercury_in_Bass/mercury_in_bass.html

Results of these types of studies

• CH3Hg+ Bioaccumulates – (higher concentrations in tissues of aquatic plants and animals than in

water) – factors can influence the bioaccumulation of mercury in aquatic biota.

These include, but are not limited to, the acidity (pH) of the water, length of the aquatic food chain, temperature, and dissolved organic material. Physical and chemical characteristics of a watershed, such as soil type and erosion or proportion of area that is wetlands, can affect the amount of mercury that is transported from soils to water bodies. Interrelationships among these factors are poorly understood and are likely to be site-specific.

• CH3Hg+ Biomagnifies – (higher concentrations at increasingly higher levels in the food chain) – Predatory fish have even more

Managing Toxins in the Environment

• EPA limit of 2 parts of mercury per billion parts of drinking water (2 ppb).

• FDA has set a maximum permissible level of 1 part of methylmercury in a million parts of seafood (1 ppm).

• OSHA has set limits of 0.1 milligram of organic mercury per cubic meter of workplace air (0.1 mg/m³) and 0.05 mg/m³ of metallic mercury vapor for 8-hour shifts and 40-hour work weeks.

http://www.epa.gov/ost/fishadvice/advice.html

Mercury in Fishhttp://www.doh.wa.gov/fish/FishAdvMercury.htm

Duwamish Riverpolychlorinated biphenyls (PCB), arsenic, mercury, tributyltin, and

polycyclic aromatic hydrocarbons

Shiner perch, flounder, English sole, rockfish from Elliot Bay, shellfish, and crab

Consume no more than one meal of any of the above mentioned fish per month.  Do not eat the hepatopancreas of crabs or the livers from above mentioned fish.  Do not eat shellfish (clams, mussels) from the Duwamish River. 

http://www.doh.wa.gov/ehp/mercury/default2.htm

Mercury in Fish 5/06

• advice for women who plan to get pregnant, are pregnant, nursing or children under six:

– For sport caught fish:– Eat no more than two meals per month of largemouth

and smallmouth bass from fresh waterbodies in Washington State. 

– For commercially bought fish:– · Do not eat any shark, swordfish, tilefish, king

mackerel or fresh caught or frozen tuna steaks. – · Limit the amount of canned tuna you eat, based on

your bodyweight.

http://www.doh.wa.gov/ehp/mercury/default2.htm

Types of Tuna

1. Albacore –white meat, highly migratory species2. Yellow fin – canned, fresh, frozen, 2nd in volume and

popularity, at its fishing limits today3. Bonito – smaller fish, moderate fat, fried or canned4. Tongol – canned white meat, not sufficient data on the

catch available5. Southern Bluefin- sashimi, most overexploited6. Northern Bluefin – canned, lives to 20 years,

overexploited7. Bigeye – light grey, fattier, similar to yellowfin8. Skipjack – most popular for consumption, canned, fresh,

frozen,

http://www.atuna.com/index.htm

Chunk Light Tuna5/06

• Women of childbearing age should limit the amount of canned chunk light tuna they eat to two cans of chunk light tuna per week (one can = six ounces, two cans = twelve ounces) based on your body weight. If you weigh 135 pounds you can eat one can (six ounces) per week, plus another fish meal low in mercury (see the list below). This second fish meal can include another serving of chunk light tuna that week.

• Children under six can eat one half can (three ounces) serving of chunk light tuna per week, plus another fish meal low in mercury that week. Specific weekly limits for children under six range from one ounce for a twenty pound child, to three ounces for a child weighing about sixty pounds.

http://www.atuna.com/species/species_datasheets.htm

Canned Albacore (White) Tuna 5/06

• Women of childbearing age should limit the amount of canned albacore (white) tuna to one can per week. If you weigh 135 pounds you can eat up to one can (six ounces) per week, but no other fish should be eaten that week.

• Children under six should eat less than one half a can (three ounces) of canned albacore (white) tuna per week. If your child has eaten canned albacore (white) tuna, your child should not eat any other fish that week. Specific weekly limits for children under six range from one ounce for a twenty pound child, to three ounces for a child weighing about sixty pounds.

To Further Reduce Your Exposure to Mercury:

• Choose canned chunk light tuna over canned albacore (white) to further reduce your exposure to mercury. Chunk light tuna has three times less mercury than canned albacore tuna.

• Eat fish that are low in mercury: light tuna, salmon, cod, flounder, pollock (imitation crab, surimi), catfish, and shrimp are smart choices.

• The major pathway for human exposure to methylmercury is consumption of contaminated fish.

– Fish and Shellfish Consumption Advisories in Washington State 

Web Sites with Information

• EPA’s Web Site -  http://www.epa.gov/mercury/about.htm• Ecology's Web Site - http://www.mercurymess.org• Washington’s Mercury Chemical Action Plan -http://

www.ecy.wa.gov/programs/eap/pbt/hginenv.html• City/County Recycling - http://

www.ecy.wa.gov/programs/swfa/contact/recyclelinks.html• The health impacts of mercury – http://www.doh.wa.gov/fish/• Fish consumption advisories - http://

www.doh.wa.gov/ehp/oehas/EHA_fish_adv.htm• Dental amalgams -

http://www.doh.wa.gov/ehp/oehas/amalgam_dental_fillings_12-2003.htm

• Nationally – bass,

– pike and

– walleye

• have higher levels of mercury than other species.

National Mercury Studies

http://water.usgs.gov/pubs/fs/fs-016-03/

Different kinds of hazards

• Chemical • Physical

– Catastrophic events, explosions

• Political– Decisions favoring development over

environmental health concerns

• Social/Cultural– Environmental justice issues

Issues with Fishing

Some say nearly 70% of the fish are at risk (Monteray Bay Aquarium)

US Commission Study-2004

http://www.oceancommission.gov/documents/prelimreport/welcome.html

Farming

• 20% of seafood farmed• Farm-raised shellfish such as oysters, clams and

mussels. EAT THEM– These shellfish are filter feeders, eating plankton from

the water, and so do not require wild fish for feed. These species can improve water quality.

– Farming shellfish in nets, trays, or racks suspended in the water is an ocean-friendly alternative to dredging

Not so good farming

• Farmed salmon is on the "avoid" list. – Dense living conditions in net pens along

coastal waters lead to disease, requiring use of antibiotics in fish feed.

– Steroids, chemical dips, vaccinations and added coloring also are widely used in farmed salmon.

– Hundreds of thousands of farmed Atlantic salmon have escaped, competing with wild salmon and diluting native genetic stocks.

• The waste from closed systems is easier to process and closed systems can better control pollution and escapes.

• "Open systems" with ponds or nets containing the fish in wetlands or at river mouths are more problematic than closed systems in general. – Then again, some Atlantic salmon farmers in Maine use

"open systems" and rotate their fish-raising pens to give these areas time to recover. This is proving effective in reducing disease and pollution

RED LIST

• Seafood on the "red" list should be avoided because it's over-fished or caught or farmed in ways that harm marine life and the environment.

• Fish in the red category includes – most shark, – Chilean sea bass, – king crab, – orange roughy, – imported shrimp and – Atlantic swordfish.

YELLOW

• Seafood in the "yellow" category is a good choice, but there are some cautionary concerns with the way it may be caught or farmed. – This includes Swordfish from the Pacific Ocean,

– king crab,

– wild clams,

– U.S. farmed shrimp or

– U.S. trawl-caught shrimp.

GREEN

• The best seafood choices always are in a "green" category, which means the fish are abundant, well managed and caught or farmed in environmentally friendly ways. These fish typically include – Alaskan wild Salmon, – wild Halibut, – farmed abalone, – farmed catfish, – farmed oysters, – trap-caught wild shrimp, and – farmed sturgeon.

Genetically Modified

• Ti plasmids in plants that infects the DNA

• Fertilized eggs can be injected with gene of interest, electrify & test for presence of that gene

•U Toronto Zoology Image

Why modify

• Faster growth

• Better taste

• Disease resistence