AQUATIC TOXICOLOGY: AquaticAquatic EcotoxicologyEcotoxicology isis aa NewNew fieldfield

• Rachel Carson, Silent Spring (1962)

Rachel Carson biographer Linda Lear, who tells the story of Carson"s courageous defense of her truths in the face of ruthless assault from the chemical industry in the year following the publication of Silent Spring and before her untimely death in 1964. • Aquatic Toxicology (Published first in 1981)

Pollutant Responses in Marine Organisms (PRIMO) THE BEAT GOES ON Polar Bears Face New Toxic Threat: Flame Retardants By Marla Cone, Times Staff Writer

Flame retardants called polybrominated diphenyls, or PBDEs, are growing at a rapid pace in people and wildlife. Although they have been found in much lower concentrations in the Arctic, scientists say their toxic legacy will persist there for years because they are slow to break down, particularly in cold climates.

PBDEs disrupted thyroid and sex hormones and damaged developing brains, impairing motor skills and mental abilities, including memory and learning. Chemicals with properties similar to PBDEs are already weakening the bears' immune systems, altering their bone structure, skewing their sex hormones and perhaps even causing small numbers of hermaphroditic bears.

Virtually every animal and person tested on Earth contains traces of brominated flame retardants. Americans have the highest levels found so far, and many U.S. women carry concentrations in their breast milk that are close to the amounts that altered the brains of newborn mice in lab tests.

Another flame retardant used in building materials and household furnishings, called HBCD, or hexabromocyclododecane, in Arctic bears. Chemists had thought it had a low potential to migrate long distances but now believe it is spreading globally. AquaticAquatic EcotoxicologyEcotoxicology isis aa ComplexComplex MultidisciplinaryMultidisciplinary ScienceScience Comparisons between Human Toxicology and Ecotoxicology.

Pharmacology/Toxicology Ecotoxicology

To protect humans against toxic exposure Protect the ecosysyem.

Target organism known Susceptible species not known, variable

Mammalian models as human proxy Direct Experiments on indicator species

Most are poikilothermic and many Models are homeothermic and static conformers Administered dosage via a number of Toxin identity, dosage and duration often routes can be measured accurately. known but many additional variables can Dosimetry available. alter dosimetry Less basic research but more empirical to Basic research: to understand mechanisms estimate threshold concentrations necessary for regulation. Methods new and are just now being Test methods well developed standardized. AQUATIC TOXICOLOGY: Some Definitions:

Aquatic: Growing living or found in water

Toxicology: The branch of science concerned with poisons, their nature, effects and antidotes.

Toxicant: Agent that cause deleterious perturbations and responses outside of the “normal” range for a healthy non-perturbed organism.

Pollution: Introduction of foreign material/substances/energy/organisms into the aquatic environment (freshwater/marine) by humans

Pollutant: Introduced foreign toxicants and substances together with physical changes that decrease the quality of the environment.

Xenobiotic: Normally refers to a synthetic, non-natural, man-made chemical that can cause deleterious effects

The Medium: all bodies of water, freshwater, brackish, saline, permanent, transient

Aquatic toxicology: a new multidisciplinary discipline evolved from pharmacology What Constitutes a Toxicant (Assumptions Underlying Toxicity):

1) Causality: Cause-Effect relationship exists (direct or indirect)

2) A dose-response or concentration -response relationship exists

a) The effect or response in question results from the toxic agent interacting with sites of toxic action in the organism

b) The dosage of toxin is related to dosage and possibly duration of exposure

c) above a statistically based threshold value the magnitude of effect is proportional to amount of toxin reaching the sites of action

d) dose and concentration relate more to potency at target site of interaction than administered external concentration

3) Effects can be quantified in an accurate and precise manner However toxic response is complex and predicated upon a number of biological, physical and chemical factors that are often hard to measure and control. ThreeThree PhasesPhases (P(P’’s)s) ofof ToxicToxic ActionAction TYPESTYPES OFOF POLLUTANT:POLLUTANT:

Major classes of pollutant can be broken down into different categories based either upon source, chemistry or effect:

• Oil • Sewage • Chemicals • synthetic organic chemicals e.g. pesticides • inorganic chemicals e.g. metals, fertilizers • Non biodegradable, persistent solid wastes. e.g. plastics, tins, cans • Thermal Pollution – power stations • Nuclear Pollution - radioactive contaminants and irradiation • Biological Pollution – introduction of non-native, alien species • Atmospheric Pollution – particles, volatile compounds, greenhouse effect, ozone depletion and acid rain. Aquatic:Aquatic: GrowingGrowing livingliving oror foundfound inin waterwater

Basic Physical and Chemical Properties of Water and Seawater and important in understanding environmental factors affecting availability toxicity and essentiality (trace essential metals) ImportantImportant PropertiesProperties ofof LiquidLiquid WaterWater