LIST OF POSSIBLE TEST CHEMICALS

boric acid:  An inorganic salt (H3BO3).  An insecticidal powder used indoors for cockroach and ant control.  Occurs in nature as the mineral, sessolite.  Used for weatherproofing wood and fireproofing fabrics.  Used externally on humans as an antiseptic, eye ointment, and antibacterial agent.  Used extensively in industry for cements, glass, leather products, carpet, soaps, cosmetics, dyeing, printing, painting, and photography.  If ingested by humans, may cause many toxic effects: vomiting, cramps, skin lesions, circulatory collapse, speeding up of the heart, and convulsions.  Known to cause reproductive and developmental toxicity effects in mammals.  A good candidate chemical for toxicity effects on worm regeneration.  Very soluble in water.

caffeine:  An alkaloid that occurs naturally in tea and coffee leaves and cola nuts.  Known to stimulate many nervous system functions, heart rate, respiration, and urine flow in mammals.  Present in caffeinated soft drinks. Active ingredient in many over-the-counter anti-sleep drugs.  Very soluble in water. (cf., Lesiuk and Drewes, 1999).

capsaicin:  Main active ingredient in red pepper, or chili pepper (genus Capsicum).  Known to affect nervous system functions and development of sensory neurons.  Creates stinging, burning sensation on skin or mucus membrane.  Used in some cat/dog repellents.  Nearly insoluble in water.  Freely soluble in ethanol.  Example of a commercial source is red pepper powder.

carbonic acid:  Dissolved CO₂ in water = carbonated water = seltzer water.  Toxic to aquatic invertebrates, such as worms.  Sometimes used by microscopists to narcotize invertebrates prior to chemical preservation.

chlorinated water:  Chlorinated water contains chlorine, a purifying agent for drinking water.  Power plant effluents produce high chlorine levels in marine and fresh waters.  Chlorine has short-term stability in water (hours or days).  Chlorinated water also contains varying amounts of chloramine, formed by the reaction of ammonia with chlorinated water.  Chloramine also has disinfectant and sanitizing properties but has longer stability in water than chlorine.  Chlorine and chloramine in water are extremely toxic to aquatic organisms, including invertebrates and fish.  Data regarding the chlorine concentration (and concentrations of other constituents) in municipal water supplies are normally available to the public from water treatment personnel.            

CMA (calcium magnesium acetate):  Used for de-icing highways.  Believed to be less toxic to aquatic life than NaCl.  Effects on many aquatic organisms are unknown.  Commercial formulation of CMA is Chevron Ice-B-Gon Deicer.  Water soluble.

ginseng:  Extracts from roots of ginseng plants (genus Panax) contain ginsenosides (types of saponins).  Used in oriental medicine as a tonic.  Claimed to enhance circulation, heart contraction and revitalization.  Believed to reduce stress and fatigue in humans.  Very water soluble.  Commercial source: Panax Ginseng Extract, available in oriental food stores, consists of a water extract from red ginseng roots that is nicely packaged as ten separate 10-ml vials intended for full-strength human consumption or dilution in other drinks.  This commercial extract, when diluted to 1/50th full strength, appears to be a potent disrupter of locomotor reflexes in Lumbriculus.  Ginsenosides, obtained from water extracts from actual ginseng roots, have potent effects on Lumbriculus blood vessel pulsation rates (S. Wong, personal communication). 

limonene:  A naturally occurring substance in lemon, orange, caraway and dill.  Constitutes about 98% of orange peel oil by weight.  Used as an insecticide and insect repellent.  Widely used for control of fleas, lice, mites and ticks.  Virtually non-toxic to warm-blooded animals, but can cause skin sensitivity and irritation.  Pleasant lemon-like odor.  Practically insoluble in water but miscible with ethanol.  Example of commercial source: “Natures Answer Flea and Tick Dip” contains 78.2% d-limonene and the label recommends diluting the product at a ratio of 3 parts product to 256 parts water (= 0.9%) and then applying directly to the pet.  Major effects, including neural and behavioral toxicity, rapidly occur in Lumbriculus at 0.009%, or less.  This is d1/100th of the recommended concentration for pets and serial dilutions can be made from this concentration.  (see Karr et al., 1990)   

nicotine:  A highly toxic alkaloid.  Principal active ingredient in tobacco products and a controlled substance. Formerly used extensively as an insecticide for home, farm, and orchard.  Nicotine in liquid form is readily absorbed through the skin (example = nicotine patch).  Effects occur at many sites within the central and peripheral nervous systems of vertebrates and invertebrates.  Mimics the action of the neurotransmitter, acetylcholine.  Symptoms of toxicity in humans include salivation, abdominal cramping, headache, loss of coordination, and respiratory failure.  Very water soluble.  An aqueous extract, made by soaking the tobacco contents of one cigarette in 100 ml of water, will provide a potent stock solution from which serial dilutions can be made.  Short-term treatment with these solutions will have major effects on Lumbriculus locomotion and blood pulsations (Lesiuk and Drewes, 1999).  CAUTION: The aqueous extracts from even one cigar or cigarette may cause serious adverse effects in humans if ingestion or prolonged contact with the skin occurs.   

pyrethrum:  An extract from flowers of a chrysanthemum grown in Africa and South America that contains several closely related insecticidal compounds (= pyrethrins).  Dried and crushed flower heads were used as a louse powder in the Napoleonic Wars.  Pyrethrins act on insects and other invertebrates with phenomenal speed, causing temporary paralysis (knock-down) but not always death.  Formulated as household insecticidal sprays and dusts for use on vegetables.  Considered generally safe to humans and domestic animals.  Not very toxic if ingested by humans because pyrethrins are hydrolyzed in the gastrointestinal tract.  Skin contact may cause dermatitis.  Synthetic pyrethrin-like compounds (= pyrethroids) are used in many commercial insecticide formulations because they may be more stable and more active than natural pyrethrins.  Pyrethroids are potent neurotoxins that modify function of voltage-gated sodium channels in neuronal membranes and induce repetitive firing of action potentials.  Practically insoluble in water but very soluble in ethanol.  Example of commercial source:  “Scratchex Power Dip For Dogs and Cats,” designed to kill fleas and ticks on contact.  Scratchex contains 0.54% pyrethrins.  The label recommends diluting 1 part from the bottle with 64 parts of water (= 0.0084%) before application to pets.  Major effects on Lumbriculus rapidly occur at 0.000084%, or less.  This is d1/100th of the recommended concentration for pets.