Environmental chemistry and toxicology: Principles and practices

1. Environmental chemistry and toxicology: Principles and practices Barry N Noller Wednesday 29 January 2014

2. OUTLINE OF TALK It is important to understand the principles of toxicology and practices of disciplines that combine in the risk assessment process to enable using Environmental Chemistry and Toxicology for understanding the nature and processes of metals and metalloids in environmental systems and their effects on biota. .

3. Significance of metals and metalloids

4. 1. Heavy metals and metalloids are toxic substances to humans and the environment and usually their effects are well defined by guidelines for soil and sediment using risk based approaches

5. 2. The common heavy metals are chromium, cobalt, copper , cadmium, lead , manganese, mercury, nickel, silver, thallium, vanadium, zinc and uranium. Antimony, arsenic and selenium are metalloids.

6. 3. Heavy metals may arise from natural and man-made sources SMI KT Short Course Practical Monitoring 22 - 24 March 2010, Brisbane

7. TOXICOLOGY Toxicology is the science of the study of poisons. It involves a multi-disciplinary approach to evaluation of the adverse impact of chemical compounds of both natural and anthropogenic origin, on various living systems. Klaassen, C.D., and D.L. Eaton. 1991. Principles of toxicology. Pp. 12-49 in Casarett and Doull’s Toxicology: The Basic Science of Poisons, 4th Ed., M.O. Amdur, J. Doull, and C.D. Klaassen, eds. New York: Pergamon Press.

8. Toxicity TESTING in the 21stCentury National research Council, 2007 The committee’s vision sets the stage for transformative changes in toxicity testing in the regulatory agencies and the larger scientific community. Although advances in the state of the science are indispensable to realization of the vision, corresponding institutional changes are also important. The changes will promote acceptance of the principles and methods envisioned. Acceptance will depend on several factors, some having scientific origins. For example, the new testing requirements will be expected to reflect the state of the science and to be founded on peer-reviewed research, established protocols, validated models, case examples, and other scientific features.

9. Toxicology and Risk Assessment Toxicology involves a multi-disciplinary approach to evaluation of the adverse impact of chemical compounds of both natural and anthropogenic origin, on various living systems. Sub-disciplines of toxicology include, environmental toxicology, (chronic impact from environment on humans), clinical toxicology, (acute impact on humans) and ecotoxicology, (impact on biota and ecological systems). Risk-assessment is a key toxicological tool that enables scientific study of the effects of poisons to proceed.

10. Venn Diagram showing Environmental Toxicology and Ecological Toxicology ENV. TOX - Environmental Toxicology ECO-TOX -Ecological Toxicology CLIN-TOX -Clinical Toxicology ENV. HEALTH-Environmental Health

11. Toxicology involves many disciplines Since there are diverse inter-disciplinary aspects to toxicology it is better displayed in the form of a Venn diagram. This diagram describes the placement of different forms of toxicology, the disciplinary aspects applying to it and associations with it. The disciplinary blocks to the right, are some of those that underpin toxicology including chemistry and are utilised in it. The separation of sub-disciplines of toxicology is clearly identified. Environmental toxicology as a human health topic, allies with public health and the environment. Ecotoxicology is placed at the interface between toxicology and the environment. The link between acute medicine and toxicology identifies clinical toxicology. Although allied to pharmacology, toxicology relates to all potential noxious agents, most having no relevance to therapeutics.

12. Central Role of RISK Assessment The central role of risk-assessment in toxicology is clearly identified when its particular application in regulatory toxicology is examined.

13. Risk Assessment Framework Human Health Risk Assessment Ecological Risk Assessment • Process followed: • Ecological / Aquatic and Agricultural / Livestock • ANZECC • Process followed: • NEPC/NEPMs • NH&MRC • USEPA • ADWG

14. Human health risk assessment (USEPA and enHealth 2012)

15. SOIL CONTAMINATION GUIDELINES Guideline values may be used to assess the Issue Identification step of Health Risk Assessment. However it is assumed that bioavailability of metals and metalloids is 100%

16. NEPM Guideline Values –Soil (< 250 µm) According to the NEPC risk assessment process, exceedances of HILs trigger require a Tier II risk assessment including toxicity assessment. Hence bioaccessibility is used to predict bioavailability and calculated for each site to allow for a site specific risk assessment. (Default is 100% bioavailability) NEPM Soil Investigation Levels (HIL = Health Investigation Levels) Level A – Standard residential with garden/accessible soil Level D – Residential with minimal soil access Level E – Parks, recreational open space and playing fields Level F – Commercial/Industrial

17. NEPM Soil Investigation Levels (HIL = Health Investigation Level and EIL = Ecological Investigation levels)

18. In cases of minor exceedances of investigation levels • or exceedances related to contaminants which have • low human toxicity and limited mobility, a qualitative • risk assessment may be sufficient. • The risk assessment process (enHealth, 2012) may • lead to the development of site-specific response • levels generated by risk assessment and agreed in • consultation between the professionals assessing • the site and the regulatory authorities. • The Tier II risk assessment process described by • NEPC (2013) allows for toxicity assessment when • HILs for the designated category or land use is • exceeded.

19. Bioavailability is defined as the fraction of the administered dose that reaches the systemic circulation of an organism (NRC, 2003). This is determined using animal dosing (in vivo) experiments. In the in vitro system, bioavailability of a contaminant is referred to as bioaccessibility and is an alternative quantitative indicator of in vivo derived bioavailability estimates. Bioaccessibility as a measure of bioavailability has been evaluated by the USEPA (2007). SMI KT Short Course Practical Monitoring 22 - 24 March 2010, Brisbane

20. The measurement of bioavailability via animal uptake is expensive and time consuming. A more practical approach is to use the in-vitro PBET (physiologically based extraction test) (Ruby et al. 1996). PBET measures bioaccessible metal and metalloid concentrations and is an in vitro test that simulates extraction by the gastro-intestinal (GI) tract of a human being (Ruby et al. 1996) to predict the bioavailability (BA) of a substance or its absorption via the gut. PBET considers a range of stomach pH’s to take into consideration varying bioavailabilities resulting from differing stomach conditions (e.g. fasting).

21. Chemical speciation of mine wastes, soils and sediments and its relationship to bioavailability in the context of health risk assessment

22. Media campaign that there was an issue Camberwell NSW

23. QLD Flood Enquiry 2012

24. Key question is how to follow the transfer of metals or metalloids through various environmental pathways

25. Contamination from Mining and Mineral processing In mineral rich countries such as Australia, mine sites are potential source of metals and metalloids Key Issues • If not properly managed, dispersion of metals and metalloids may cause adverse effects on the environment and human health • Major environmental source of metals and metalloids including arsenic, cadmium, copper, lead and zinc through their associations with base metal mineralogy • Contamination can arise from mine processing of ores, overflow from tailings ponds, and run-off from the general mine area which can lead to extensive offsite contamination. • Contamination of soil and water by metals and metalloids from both mining residues and tailings can result in bioaccumulation by terrestrial and aquatic biota and to human uptake

26. Lead from Mining and Mineral Processing • Significant geographical distribution (radially from the smelter) of lead in town receptor (soil, air, and blood lead level) • Port Pirie, SA – BLL following the major wind direction; high risk • area is downstream of the lead smelter (Calder et al., 1994) • Ongoing smelter emission as point source • Trail, Canada – improvement following a new smelter (5.9 µg/dL from 11.5 µg/dL); 3-month shutdown (4.7 µg/dL) (Hilts, 2003) • Exterior soils and interior dusts • Ingestion vs Inhalation • Birmingham, UK – 97% lead from ingestion & 3% from inhalation for 2 year old children (Davies et al., 1990)

27. Example of Lead Sources and Metabolism Mining Food/water House yard Smelter Natural environment (US EPA, 1994)

28. Exposure Pathways • Dermal Absorption – very minimal impact • Inhalation - Air-borne dust (-150 µm soil fraction) inhale, • cough-out then swallow • Ingestion - Hand-to-mouth activity (-250 µm soil fraction) • Adult: 25 mg/day • Child-Youth (>5 -15y): 50 mg/day • Young Child (>0 - 5y): 100 mg/day • Pica: 10 g/day Hand to mouth (<250 µm) Inhalation Dermal Ingestion Thoracic (<10 µm) Respirable (<2.5 µm)

29. Lead via Ingestion Pathway • The Integrated Exposure Uptake Biokinetic (IEUBK) model by US EPA: default value used for children is 30%. • Ingestion: Hand-to-mouth activity (<250 µm soil fraction) • Adult: 25 mg/day • Child-Youth (>5 -15y): 50 mg/day • Young Child (>0 - 5y): 100 mg/day • Pica: 10 g/day Human GI track (US EPA, 1994)

30. Stokes’ Law applied to particles (D>1.5 µm) (Finlayson-Pitts and Pitts Jr, 2000) Where: v is the particle velocity (m/s); g is the gravitational acceleration (9.8 m/s2 at sea level); ρp is the mass density of the particles (kg/m3); ρair is the air density (1.2 × 10-3 g/cm3 at 20 ℃ and 1 atm pressure) D is the particle diameter (m); η is the gas viscosity (0.00001837 Pa s). High wind speed Low density Distance

31. Importance of particle size • PM10 (particulate matter <10 µm ） • PM2.5 (particulate matter <2.5 µm ） • PM250 - ingestion (hand to mouth) Hand to mouth (<250 µm) Thoracic (<10 µm) Respirable (<2.5 µm) (Modified from SKC Inc.)

32. National Environment Protection (Ambient Air Quality) Measure (Air NEPM) standards and EPA Air EPP goal (EPA 2006 and NEPC 2003) # not to be exceeded more than five days per year ;¶ NEPM Advisory Standard

33. Lead in Environment • Lead minerals: galena (PbS) (primary), anglesite (PbSO4), cerrusite (PbCO3), massicot (PbO), litharge (PbO), leadhillite (Pb4(SO4)(CO3)2(OH)2)), Pyromorphite, (Pb5(PO4)3Cl), and Pb silicate. • Artificial lead from smelting: fine galena particles, PbO, Pb • Plumbogummite, plumbojarosite, goethite absorbed lead, and humic acid absorbed Pb in environmental samples.

34. Background to • Environmental • Monitoring

35. Background to Environmental Monitoring • Identify and characterise hazardous chemicals • Assess risks posed by hazardous pollutants on human health and the environment and risk associated with the cycle of hazardous wastes • Apply fundamental principles of waste management and risk management to manage contaminated sites • Develop a fundamental understanding of principles of waste management • Strategies for waste minimisation

36. Mining2 main processes • Mining • Mineral Extraction Process • Other separation process

37. Phases of Mining(plan at the start) • Pre-mining • During mining • Post mining • Rehabilitation • Future land use

38. Waste Production from Mining • Mining • Mine waste dumps • Mineral extraction process • Mine tailings

39. Environmental Sampling at Mine or Contaminated Sites • Monitoring programs involving sampling of water, noise and dust are generally mandatory, at least in the initial stages of the mining venture • Environmental Impact Statement (EIS) initiated programs

40. Environmental Sampling at Mine Sites • Results from monitoring programs assessed by mining company and those regulatory agencies with appropriate expertise as part of the review of the Annual Environmental Management Report (AEMR)

41. Environmental Sampling at Mine Sites • Basic Aims of Sampling • Program objectives • Determinands of interest • When, where and how for sampling • Testing methods to be used • How sample taken and preserved • Reporting of results • What happens to reported results

42. Design of a SamplingProgram (Based on Maher et al., 1994) Sampling hypothesis needs to be stated Consider: Problem/Question Objectives Model Indicators Hypothesis Sampling Scheme relates to the Sampling Objectives and Hypothesis by considering: Cost Effectiveness

43. PROBLEM / QUESTION OBJECTIVES MODEL COST EFFECTIVENESS INDICATORS SAMPLING SCHEME HYPOTHESES replication site selection frequency FIELD COLLECTION storage / transport quality assurance collection device Framework for designing a sampling program

44. Primary SamplingApproaches

45. Environmental Sampling • Results from analysis of samples used to decide exceedances of environmental guidelines • Validity of sample taking/sample analysis • Not possible to transform bad (non - representative sample into good sample • Sampling must be carried out with strict adherence to relevant sampling standards

46. Sampling approaches

47. Standard Methods • AS (1990) AS3580 9.6, Methods for Sampling and Analysis of Ambient Air, Method 9.6: Determination of Suspended Particulate Matter-PM10 High Volume Sampler with Size-Selective Inlet-Gravimetric Method, and 9.7: Determination of Suspended Particulate Matter-PM10 Dichotomous Sampler-Gravimetric Method, Standards Association of Australia, Strathfield NSW. • AS (2000) AS 4874 “Guide to the investigation of potentially contaminated soil and deposited dust as a source of lead available to humans”. Standards Association of Australia, Strathfield NSW.

50. Microvol PM 10 Fall –out collector