The Arsenic Project Chemical Measurements in Support of Studies of the Biogeochemistry of Arsenic

The Arsenic Project Chemical Measurements in Support of Studies of the Biogeochemistry of Arsenic Julian Tyson Department of Chemistry UMass Amherst MA 01003 tyson@chem.umass.edu http://courses.umass.edu/chemh01/ Outline of “The Arsenic Project” talk Background to my involvement Background on arsenic: environment and health Pressure treated wood Arsenic in water Other sources of arsenic Middle school and undergraduate researchers Measurement problems: soils and water High tech: HPLC- HG-ICP-OES; low tech: test strips What is research? Background to “The Arsenic Project” Loughborough U 76 - 89: UMass 89 - present J F Tyson , S G Offley, N J Seare, H A B Kibble and C Fellows, "Determination of arsenic in a nickel based alloy by flow injection hydride generation atomic absorption spectrometry incorporating by continuous flow matrix isolation and stopped flow pre-reduction procedures," J Anal At Spectrom., 1992, 7, 315-322 Peter Yehl: my first student to work on issues of arsenic (from pressure-treated wood) obtained his Ph.D in 1996 Since then, at least one Ph.D student has worked on arsenic-related topics every year Background to “The Arsenic Project” Started with trying to answer the question, “What happens to the arsenic that leaches out of wood pressure-treated with chromated copper arsenate?” Three hypotheses: (1) it forms insoluble compounds with soil, (2) it is washed away by surface water runoff, and (3) it evaporates, because soil bacteria convert it to volatile methylated compounds Needed methods to measure the various arsenic compounds in soils Turned out to be very difficult! Background to “The Arsenic Project” This led to my suggestion that tracking the arsenic from PTW as part of an “arsenic in the environment” theme would be a suitable for our GK-12 program Started in summer of 2002 Needed a procedure for the determination of arsenic to support studies by the middle-school student participants Issues: cost, safety, limit of detection (LOD), speed Picked the Hach version of the “Gutzeit” test designed to measure As in drinking water Background to “The Arsenic Project” Awareness of the PTW source led to my suggestion that tracking the arsenic from PTW as part of an “arsenic in the environment” theme would be a suitable for our GK-12 program Started in summer of 2002 Needed a procedure for the determination of arsenic to support studies by the middle-school student participants Issues: cost, safety, limit of detection (LOD), speed Picked the Hach version of the “Gutzeit” test designed to measure As in drinking water But it has limitations Background to “The Arsenic Project” Can we better? This led to a research project, supported by NSF, into the possibility of pervaporation with visible spectrophotometry Started in fall 2003 Also an interest in the general need for inexpensive, reliable, field-deployable, simple, technologies for the determination of arsenic at realistic concentrations i.e with an LOD of < 10 ppb (or ng mL-1 or µg L-1) Fall 2004 Creation of authentic research experiences for first-year undergraduates more info at the arsenic project website: http:://courses.umass.edu/chemh01/ Background to “The Arsenic Project” Mandal and Suzuki, “Arsenic around the world” Talanta, 2002, 58, 201-235 Uses: insecticides, herbicides, desiccant (cotton production), wood preservative, feed additive, medicine, poison, bullets, electronics, glass, paints, wallpapers and ceramics Our quality of life affected by the extent to which we can (a) minimize the harmful effects of naturally occurring chemicals, (b) exploit beneficial effects of chemicals with which we choose to interact Update on “The Arsenic Project” “The World Health Organization (WHO) recommends a tolerable daily intake of 50 µg/kg body weight from food and no more than 20 µg/L in the drinking water (WHO, 1983).” http://www.prn.usm.my/sites/arsenic.html (accessed April 2005) The arsenic project: acknowledgements NSF awards DUE 0139272 Graduate Students in GK-12 Education (GK-12) “STEM Connections”, June 2002 and is currently in a no-cost extension period NSF 0316181 “Integrating Research and Education: tracking arsenic from pressure-treated wood” started in July 2003 UMass Center for Teaching: Faculty Grant for Teaching Sept 2005 Camille and Henry Dreyfus Foundation: Special Grant Program in the Chemical Sciences Feb 2006 The arsenic project: facts and figures CCA Percentage of Type A Component max Type B Type C min CrO3 59 - 69 33 - 38 44 - 51 CuO 16 - 21 18 - 22 17 - 21 As2O5 15 - 20 42 - 48 30 - 38 max max 300,000 metric tons of inorganic arsenic have been used for wood preservation since 1975 The arsenic project: facts and figures PTW As of December 2003 is no longer sold Up till then about x 108 ft3 of wood pressure-treated with CCA was made every year Depending on formulation the material contains 4.0, 6.4 or 13 kg m-3 of CCA The acute lethal oral dose is - 2.5 mg kg-1 For 75 kg adult this is 75 - 188 mg This is, for best case scenario, 313 cm3 or a cube cm on the side Worst case scenario: 2.3 cm cube The arsenic project: facts and figures Total arsenic in PTW was measured to be 0.2% i.e 2,000 ppm i.e 2,000 mg kg-1 or g kg-1 To get a minumum lethal dose: eat 3.8 g of wood If density is 0.5 g cm-3 This is a 2-cm cube Katz and Salem, J Appl Toxicol., 2005, 25, 1-7 The density of arsenic trioxide is 3.74 g cm-3 A 100 mg lethal dose is a cube of side mm The arsenic project: facts and figures About 35 µg cm-2 of As can be dislodged from aged PTW The Hach test kit can detect 500 ng (just) 35 µg in 50 mL is 700 ppb (top end of the scale) Contaminated soil might contain 40 ppm If a 1-g sample is taken, the mass in test kit would be 40 µg (800 ppb) The arsenic project: facts and figures Cost of Hach EZ test kit: $50.60 (100 tests and reaction vessels with caps, plus reagent to eliminate sulfide interference) Reagent set for 100 tests: Reaction vessel (one): Cap (one): $33.00 $5.50 $2.50 Shipping; $14.00 Research: Creation and Dissemination of New knowledge How is research done? By: scientists working in industry, government labs, and universities and colleges Most organizations have a large number of research groups, whose members collaborate Most groups are relatively small (< 10) Groups are dynamic New members join; older members move on Leadership is stable New members learn from the more experienced members Research: Creation and Dissemination of New knowledge New members need training: Background to problem (big picture, what is already known), How to find out (library) Techniques to be used, Hypothesis to be tested, Plan of action (experimental design) Communication skills (written and oral) Research: Creation and Dissemination of New knowledge How is new knowledge communicated? Within members of research group Conference presentations (oral or poster) Scientific literature: reviewed journal articles Researchers write manuscripts, submit to journal editor Editor sends to reviewers Reviewers send back comments (anonymously) Researchers revise Article is published and work is scrutinized Recent work is reviewed periodically by experts who write “review articles” Important stuff eventually finds its way into textbooks Research: Creation and Dissemination of New knowledge Importance of chemical analysis Many investigations need information about chemical composition of relevant materials Often it is difficult to provide this information All researchers need to know about the scope and limitations of chemical measurement methods Often these are set by the instrument that is to be used An authentic research experience involves: Working on a real problem, Over an extended time period, Working in a team with more experienced workers, Finding out about your topic, Devising a plan of work, Conducting experiments and interpreting the results, Devising new experiments, Sharing your findings by writing and talking about what you are doing/have done [...]... Measurement of Arsenic in Hair and Nails 4 Spectrophotometric Determination of Arsenic in Water: Flow injection molybdenum blue method 5 Spectrophotometric Determination of Arsenic in Plants: The Molybdenum Blue Method Student Activities in The Arsenic Project 6 Spectrophotometric Determination of Arsenic in Pressure-Treated Wood: Silver diethyldithiocarbamate method 7 Determination of arsenic in wood by inductively... using oxalic acid extraction: the mapping of copper chromated arsenate wood on the University of Massachusetts Amherst Campus 8 Metabolism of Arsenic in E Coli 9 Analyzing the spatial distribution of arsenic in soil using the Hatch Test Kit and soil from the Amherst area 10 Effectiveness of Solvents in the Removal of Arsenic from Soil 11 Evaluating and Improving a Commercial Test Kit for the Determination... 4aminophenylarsonic acid The end of the metabolic path? trimethylarsine oxide TMAO tetramethylarsonium iodide Arsenosugars: Found in urine and seaweed arsenobetaine AsB Present in high concentrations in seafood arsenocholine AsC Background to The Arsenic Project According to a recent NSF report: About 80% of school students decide, by the time they enter high school, that they are not interested in. .. Mongolia, Peru, Thailand and the United States of America  Adverse health effects documented in: Bangladesh, China, India (West Bengal), Mongolia and the United States of America  Arsenic in drinking-water will cause 200,000 – 270,000 deaths per year from cancer in Bangladesh alone Arsenic contaminated water revealed in 1993 4.5 million tube wells Arsenic contamination in 20% of those tested Environmental... Recent studies estimate that 2-100 children per million exposed to PTW during early childhood may develop lung or bladder cancer later in life as a result of this exposure Consumer Product Safety Commission (2003) Some arsenic compounds are not so bad Some of the good guys Salvarsan: used to treat syphilis until the advent of penicillin in the 1950s Neoarsphenamine: used in the treatment of syphilis... www.nsf.gov/geo/ere/ereweb/acere_synthesis_rpt.cfm (accessed April 2005) Student Activities in The Arsenic Project http://courses.umass.edu/chemh01/ Undergraduates: Now in 5th semester Each group has 2-3 freshmen and 1-2 juniors and a graduate student mentor Final reports from spring semester 2006 1 Removal of Arsenic from Drinking Water: Chemical Means: Arsenic Removal by Iron Precipitation in Alkaline Solutions 2 Arsenic. ..Update on The Arsenic Project Chemical form or speciation is all important E.g Sodium is nasty, chlorine is even worse But swap an electron between them and make sodium chloride, and the resulting compound is essential Not quite the same for As, as there are no known essential compounds (in humans) But there is a very wide range of toxicities Update on The Arsenic Project Chemical form... important The most toxic are arsenite, As(OH)3, arsine AsH3 and the methylated forms of AsIII MMAIII and DMAIII CH3 As OH OH CH3 As OH CH3 These are more toxic than the corresponding +5 species, which in turn are more toxic than arsenate, As(O)(OH)3 Intake of 70 to 300 mg of arsenic trioxide may be fatal Death typically occurs between 12 to 48 hours but can occur within one hour Those who survive arsenic. .. poisoning may develop encephalopathy or severe peripheral neuropathies Symptoms of acute poisoning usually occur within one hour of ingestion but may be delayed for up to 12 hours, particularly in the presence of food The principle toxic effects are hemorrhagic gastro-enteritis, profound dehydration, cardiac arrhythmias, convulsions, muscle cramps, shock and death http://www.gettingwell.com/drug_info/nmdrugprofiles/nutsupdrugs/ars_0... http://www.gettingwell.com/drug_info/nmdrugprofiles/nutsupdrugs/ars_0 026.shtml (accessed April 2005) Toxicity from dietary intake of arsenic up to 60 µg/day daily—is relatively low Intakes of higher amounts of arsenic on a chronic basis may cause hyperkeratosis, especially of the palms and soles, skin pigmentation, eczematous or follicular dermatitis, edema (especially of the eyelids), alopecia, muscle-aching and weakness,