DECISION PROTOCOLS FOR CYANOBACTERIAL TOXINS

Transcription

1 Page 1 PART B: Decisin Prtcls fr Cyanbacteria Txins DECISION PROTOCOLS FOR CYANOBACTERIAL TOXINS IN B.C. DRINKING WATER AND RECREATIONAL WATER 1. Purpse The purpse f these prtcls (recreatinal water and drinking water) is t prvide standardized prcesses (steps) fr water suppliers, lcal gvernments and health authrities t fllw when mnitring cyanbacterial blm events. Each prtcl recmmends actins that shuld be taken t address ptential cyanbacterial blms and assciated micrcystin issues. Examples include directing a water supplier t switch t an alternative water surce, issue a D Nt Use ntice r warn recreatinal water users f unacceptable water quality befre it becmes a health hazard. The decisin trees in these prtcls are mdified frm the Health Canada s Guidelines fr Canadian Drinking Water Quality: Supprting Dcumentatin: Annex A: Stepwise Prtcl fr Micrcystin-LR in Water Supplies Used fr Human Cnsumptin, and Cyanbacterial Txins in Drinking Water Dcument fr Public Cnsultatin (prepared by the Federal-Prvincial-Territrial Cmmittee n Drinking Water, 2002).1 This dcument als takes int accunt interim drinking water advice n micrcystins prvided by Health Canada n June 17, This includes the additin f precautinary advice cncerning infants, as a result f the cllabrative assessment undertaken by Health Canada and the United States Envirnmental Prtectin Agency: A seasnal maximum acceptable cncentratin (seasnal MAC) f mg/l (1.5 μg/l) is prpsed fr ttal micrcystins in drinking water. This guideline is cnsidered t be prtective f the general ppulatin, including yung children. Because f the increased expsure f infants relative t bdy weight, as a precautinary apprach during a cyanbacterial blm, r when micrcystins are detected in finished water, drinking water authrities shuld cnsider infrming the public in the affected area that an alternate suitable surce f drinking water (such as bttled water) shuld be used t recnstitute infant frmula. The gal f this dcument is t simplify the steps in the riginal prtcl by separating drinking water and recreatinal water, and incrprating additinal screening indicatrs that may reduce the csts assciated with sampling. It als incrprates screening fr the brader micrcystin txin as risk indicatr rather than the mre specific Micrcystin-LR that is in the current Health Canada advice. These prtcls and the accmpanying decisin trees summarize the imprtant factrs that shuld be cnsidered during blm events and recmmended actins that may be taken t address the issue. 1 Health Canada, Guidelines fr Canadian Drinking Water Quality: Supprting Dcumentatin, Cyanbacterial Txins Micrcystin-LR. Available nline at

2 Page 2 PART B: Decisin Prtcls fr Cyanbacteria Txins 1. Backgrund Infrmatin n Cyanbacteria The grwth f cyanbacteria (als knwn as blue-green algae) in water bdies (generally smaller r shallw lakes, reservirs, slughs r duguts) can ccur thrughut Canada at any time f year, but blms happen predminantly in the summer. In many cases, blms tend t recur within the same water bdies year after year. While mst species f cyanbacteria are capable f prducing nerve and liver txins, nt all d. When present, the amunt f txin can vary dramatically within the bdy f water and ver time. Analytical studies in duguts and ther water supplies in Manitba, Saskatchewan and the Peace River regin f Alberta indicate that cyantxins (i.e., micrcystins) are much mre cmmn in rural water supplies than riginally thught. Althugh there are few quantitative surces f data available, there are indicatins that these txins may als be ccurring in varius water supplies in ther prvinces (e.g., Ontari, British Clumbia, Quebec and PEI). This has led t increasing cncern by gvernment agencies and the public abut the safety f water supplies that may be ptential surces f these txins. The factrs inducing the prductin f txins by cyanbacteria are cmplex. Labratry studies demnstrate that sme envirnmental factrs culd be imprtant, such as temperature, light, nitrgen cncentratins, carbn availability (in the frm f bicarbnate, carbnate and carbn dixide), phsphate cncentratins and ph. As txin prductin varies greatly amng different strains f the same species, genetic differences and metablic prcesses may als be imprtant in the prductin f these secndary metablites. Studies have shwn that the ability t prduce txins can vary temprally and spatially at a particular site. Therefre, different parts f the same water bdy may have different cncentratins, and this shuld be cnsidered when deciding n testing prtcls. Cyanbacterial txins tend t be assciated with cyanbacterial cells and may be membrane-bund r ccur free within the cells. In labratry studies, mst f the txin release ccurs as cells age and die and passively leak their cellular cntents. Sme active release f txins can als ccur frm yung, grwing cells. Txin levels d nt necessarily cincide with maximum algal bimass. There can be a significant variatin in the amunt f txin per unit bimass f cyanbacteria ver time, which is independent f changes in the blue-green algal ppulatin. In ne study, fr example, cncentratins f micrcystins were higher in blm samples taken during the day than at night. In anther study, n significant difference was bserved in txin cncentratins frm cyanbacteria incubated fr 24 hurs at different depths in a reservir. Micrcystins are relatively persistent in the aquatic envirnment. Studies in Australia have shwn that Micrcystin-LR was present up t 21 days fllwing treatment f a Micrcystin aeruginsa blm with an algaecide. 2. Sampling, Prtable Test Kits and Labratries Agencies typically invlved with cyantxin testing f raw and drinking water surces include the Ministry f Envirnment and Climate Change Strategy (reginal ffices), lcal gvernments, water system peratrs and health authrities envirnmental health fficers. These agencies shuld make themselves familiar with these prtcls and wrk tgether t develp lcal cmmunicatin prtcls befre blm events. They shuld ensure each grup understands their rle with respect t bservatin, sampling and decisin-making fr a given surce f drinking r recreatinal water.

3 Page 3 PART B: Decisin Prtcls fr Cyanbacteria Txins This dcument refers t field test kits methds and labratry testing. T limit the ptential fr errr when using the prtcls, field testing fr micrcystins is intended t determine their presence r absence nly within the sample (vs. a specific quantifiable amunt), as field test kits have a range f detectin limits, and levels f accuracy/reliability vary. Subsequent t field tests shwing the presence f micrcystins, samples shuld be frwarded t an analytical labratry t cnfirm whether micrcystin cncentratins exceed the recmmended threshlds. A number f cmmercial micrcystin tests kits suitable fr field use are available. These are discussed in the recent Health Canada reprt Evaluatin f Field Test Kits t Detect Micrcystins. 2 They include technlgies based n ELISA, immunchrmatgraphy, and phsphatase inhibitin. When chsing a prtable test kit, it is imprtant t pick ne that is apprpriate fr the range f txin cncentratins being screened fr (i.e., 0.5 µg/l t 5µg/L fr drinking water, and a higher range fr recreatinal water). In sme cases, where the test kit range is belw threshlds (as in recreatinal water), dilutin f samples with fresh water may be required t prvide results test within the range f interest. Several B.C. labratries are equipped t test specifically fr micrcystins. Sampling agencies shuld determine, in cnsultatin with the lcal health authrity, where and hw t send samples fr analysis well befre any blm event ccurs. A descriptin f apprpriate labratry techniques is discussed in the supprting dcumentatin fr Health Canada s guidance n cyanbacterial txins. 3 2 Rdriguez, R. Evaluatin f Field Test Kits t Detect Micrcystins. Envirnmental Prtectin Agency, Available nline at 3 Health Canada, Guidelines fr Canadian Drinking Water Quality: Supprting Dcumentatin, Cyanbacterial Txins Micrcystin-LR. Available nline at

4 Page 4 PART B: Decisin Prtcls fr Cyanbacteria Txins Decisin Tree fr Drinking Water: Cyanbacterial Txins

5 Page 5 PART B: Decisin Prtcls fr Cyanbacteria Txins Decisin Tree fr Drinking Water: Cyanbacterial Txins Step Descriptins STEP A: Initial screening fr suspected blms: Examine the water fr ne r mre f ttal nitrgen and phsphrus. Check fr blm frmatin. Test fr nitrgen/phsphrus: Spring turnver typically results in an increase in water nutrients cycled t the surface. This nutrient cycling cupled with increased sunlight and temperature can prvide the cnditins that lead t an algae blm. Testing fr phsphrus and/r nitrgen may serve as an alert fr impending algal blms and increasing the frequency f visual checks. Visually check fr blm frmatin: As blms tend t recur in the same water supplies, water bdies that have histrically exhibited algal blms shuld be visually mnitred fr blm frmatin. As well, water bdies that experience changes in variables such as temperature, size, water depth and nutrient cntent may be susceptible t algal blms and shuld be cnsidered fr increased mnitring. Public enquiries/cmplaints may als serve as a flag t check fr blms. A visual blm is identified by the appearance f supy water. Clurs can range frm grey r tan, t blue-green r bright blue, t reddish. The appearance f blms may als be described as fine grass clippings r small clumps. Changes in secchi (cludiness/turbidity) depth readings may be a sign f an impending blm. STEP B: If yes t any f: nitrgen (N)>658 µg/l; phsphrus (P)> 26µg/L; an N:P rati < 23; changes in secchi depth; r blms bserved, g t Step C. If n, return t Step A. High levels f nitrgen and phsphrus, as well as lw rati f nitrgen t phsphrus, can cntribute t algal blms and the presence f micrcystins. Accrding t Orihel et al., 95% percent f the cases where micrcystin cncentratins exceed the WHO drinking water guideline ccur with phsphrus cncentratins abve 26 µg/l and nitrgen cncentratins abve 658 µg/l. Maximum cncentratins f micrcystins ccur in hypereutrphic lakes at mass ratis f N:P belw 23. The prbability f micrcystin cncentratins exceeding all txin threshlds is highest when N:P ratis are less than 20, and drp t near zer abve N:P rati f As grwth cnditins and nutrient cntent f each water bdy are unique, these numbers are prvided as a screening reference fr anticipating the risk f a blm. They are nt intended t be exact threshlds. Fr a ratinale n blm bservatin, see step A, secnd bullet (abve). STEP C: Sample the raw water. Use a prtable field kit t test fr the presence f micrcystins. Raw water samples shuld be cllected befre any treatment. Sampling frm a reservir shuld be dne as clse t the inlet/shre and/r the blm frmatin as pssible. When chsing a sampling 4 Orihel, Diane M. High micrcystin cncentratins ccur nly at lw nitrgen-t-phsphrus ratis in nutrient-rich Canadian lakes. Canadian Jurnal f Fisheries and Aquatic Sciences. NRC Research Press, August 14, 2012.

6 Page 6 PART B: Decisin Prtcls fr Cyanbacteria Txins lcatin, be aware that cyanbacterial species/cell abundance and bimass vary spatially within a water bdy (e.g., cells may be transprted by wind currents). Fr the purpse f this decisin prtcl, the presence f micrcystins means >1.0µg/L using a prtable test kit. See Evaluatin f Field Test Kits t Detect Micrcystins regarding hw t select a prtable test kit. 5 Be aware that txins may persist fllwing the cllapse f blms. This can happen particularly in the late summer and early fall, when clder temperatures and a decrease in light intensity result in decreased rates f txin degradatin. This may indicate a need fr sampling fr txins during and after cllapse f the blm. Further sampling (ptinal) fr algal identificatin may als be helpful. Species identificatin, especially frm sites psitive fr txin, can prvide additinal infrmatin regarding the surce, cnditins and type f ther txins that might be present. STEP D: If the presence f micrcystins is detected (>1.0µg/L ) with a field test kit, g t step E, and alert the health authrity f a ptential issue. If micrcystins are absent, return t step A. STEP E: Use a prtable test kit t test the treated water supply fr micrcystins. Samples shuld be taken at a tap lcated after treatment frm the water plant r frm within the distributin system. STEP F: If the prtable test kit indicates micrcystins are present (>1.0µg/L) in the treated water, send a sample t the lab fr cnfirmatin and immediately ntify the health authrity. The presence f micrcystins indicates there is a ptential cncern fr infants wh use frmula recnstituted frm that water. Cnsult the health authrity abut infrming the public that an alternate surce f drinking water shuld be used fr recnstituting infant frmula. Cntact the health authrity t cnfirm an apprpriate labratry fr micrcystin testing. Samples fr lab analysis shuld be cllected in glass cntainers r as directed by the lab, as studies indicate that the txin, if present, can be adsrbed t plastic. STEP G: If the lab results indicate the seasnal MAC f 1.5µg/L has been exceeded, immediately cntact the health authrity fr cnsultatin and decisin-making. Where lab analysis indicates that levels f micrcystin are near r exceed the seasnal MAC f 1.5µg/L, the health authrity shuld be cnsulted t determine a shrt-term and lng-term curse f actin. Health agencies, municipal cuncils and water supply system peratrs shuld be included in these discussins. Factrs t cnsider may include the site histry, size and lcatin f the blm, available treatment technlgy, uses f the surce water (recreatinal vs. dmestic uses) and mnitring f the envirnmental cnditins that might affect 5 Rdriguez, R. Evaluatin f Field Test Kits t Detect Micrcystins. Envirnmental Prtectin Agency, Available nline at

7 Page 7 PART B: Decisin Prtcls fr Cyanbacteria Txins the blm (e.g., wind). Water system peratrs may be able t prvide infrmatin abut the histrical ccurrence f blms/micrcystins fr a given system. In respnse, the water supplier may need t d ne r mre f the fllwing: Resample the treated water supply using a field kit r labratry, r d ther mnitring. Use an alternate water surce r supply. Discussins regarding alternative supplies shuld be reviewed with the health authrity. Adjust treatment (if ding s will be effective). Discussins regarding treatment adjustments shuld be reviewed with the health authrity. Issue a D Nt Use ntice. See appendix B fr suggested messaging. As blms may be f shrt duratin (ranging frm days t weeks), the health authrity may recmmend that a D Nt Use ntice be issued, and that cnsumers seek alternative supplies f safe drinking water until the risk passes. Any D Nt Use ntice shuld remain in effect until tw cnsecutive water samples (fr bth raw and treated supplies) are tested and cnfirmed t be less than their respective threshlds fr micrcystins. Maintain the status qu (cntinue mnitring). Take ther actins as required by the health authrity. Lng-term issues and/r recurrence f cyanbacteria blms may require planning t incrprate specific treatment t crrect the prblem, and the use f an alternate surce f water in the interim.

8 Page 8 PART B: Decisin Prtcls fr Cyanbacteria Txins Decisin Tree fr Recreatinal Water: Cyanbacterial Txins

9 Page 9 PART B: Decisin Prtcls fr Cyanbacteria Txins Decisin Tree fr Recreatinal Water: Cyanbacterial Txins Step Descriptins STEP A: Initial screening fr suspected blms: Examine the water fr ne r mre f ttal nitrgen and phsphrus. Check fr blm frmatin. Test fr nitrgen/phsphrus: Spring turnver typically results in an increase in water nutrients cycled t the surface. This nutrient cycling cupled with increased sunlight and temperature can prvide the cnditins that lead t an algae blm. Testing fr phsphrus and/r nitrgen may serve as an alert fr impending algal blms and increasing the frequency f visual checks. Visually check fr blm frmatin: As blms tend t recur in the same water supplies, water bdies that have histrically exhibited algal blms shuld be visually mnitred fr blm frmatin. As well, water bdies that experience changes in variables such as temperature, size, water depth and nutrient cntent may be susceptible t algal blms and shuld be cnsidered fr increased mnitring. Public enquiries/cmplaints may als serve as a flag t check fr blms. A visual blm is identified by the appearance f supy water. Clurs can range frm grey r tan, t blue-green r bright blue, t reddish. The appearance f blms may als be described as fine grass clippings r small clumps. Changes in secchi (cludiness/turbidity) depth readings may be a sign f an impending blm. Be aware that txins may persist fllwing the cllapse f blms. This can happen particularly in the late summer and early fall, when clder temperatures and a decrease in light intensity result in decreased rates f txin degradatin. This may indicate a need fr sampling fr txins during and after cllapse f the blm. STEP B: If yes t any f: nitrgen (N)>658 µg/l; phsphrus (P)> 26µg/L; an N:P rati < 23; changes in secchi depth; r blms bserved, g t Step C. If n, return t Step A. High levels f nitrgen and phsphrus, as well as a lw rati f nitrgen t phsphrus, can cntribute t algal blms and the presence f micrcystins. Accrding t Orihel et al., 95% percent f the cases where micrcystin cncentratins exceed the WHO drinking water guideline ccur with phsphrus cncentratins abve 26 µg/l and nitrgen cncentratins abve 658 µg/l. Maximum cncentratins f micrcystins ccur in hypereutrphic lakes at mass ratis f N:P belw 23. The prbability f micrcystin cncentratins exceeding all txin threshlds is highest when N:P ratis are less than 20, and drp t near zer abve N:P rati f As grwth cnditins and nutrient cntent f each water bdy are unique, these numbers are prvided as a screening reference fr anticipating the risk f a blm. They are nt intended t be exact threshlds. Fr a ratinale n blm bservatin, See step A, secnd bullet (abve). 6 Orihel, Diane M. High micrcystin cncentratins ccur nly at lw nitrgen-t-phsphrus ratis in nutrient-rich Canadian lakes. Canadian Jurnal f Fisheries and Aquatic Sciences. NRC Research Press, August 14, 2012.

10 Page 10 PART B: Decisin Prtcls fr Cyanbacteria Txins STEP C: Sample raw water. Use a prtable field kit t test fr micrcystins. Samples shuld be taken as clse t beaches r recreatinal sites as pssible. Hwever, if sampling agency resurces are available, it is suggested that samples frm several sites be taken and tested fr the presence f micrcystins, as cyanbacterial bimass varies spatially within a water bdy (e.g., cells may be transprted by wind currents). See Evaluatin f Field Test Kits t Detect Micrcystins regarding hw t select a prtable test kit. 7 Further (ptinal) sampling fr algal species identificatin may als be helpful. Species identificatin especially frm sites psitive fr txin identificatin can prvide additinal infrmatin abut the surce, cnditins and type f ther txins that might be present. STEP D: If the presence f micrcystins is detected with a field test kit (>1µg/L), send a sample t the lab fr quantitative analysis. Fr the purpse f this prtcl, presence f micrcystins means >1.0µg/L using a prtable test kit. See Evaluatin f Field Test Kits t Detect Micrcystins regarding hw t select a prtable test kit. Cntact the health authrity t cnfirm an apprpriate labratry fr micrcystin testing capability. Samples shuld be sent (in clers) t the labratry fr analysis and cllected in glass cntainers r as directed by the lab, as studies indicate that the txin, if present, can be adsrbed t plastic. STEP E: Health authrity cnsultatin and decisin-making. Where the labratry analysis indicates that levels f micrcystins are near r exceeding the threshld f 20 µg/l, the health authrity shuld be cnsulted t determine a shrt-term and lng-term curse f actin. Health agencies, municipal cuncils and water supply system peratrs shuld be included in these discussins. Factrs t cnsider may include the site uses (e.g., swimming), size and lcatin f the blm, envirnmental cnditins (e.g., wind) and histry f the water bdy. The authrity respnsible fr the recreatinal water bdy may need t d ne r mre f the fllwing: Resample the water immediately and send the resample t lab fr cnfirmatin f result. Take apprpriate actin(s), which may include: Pst Beach Clsed and ntify the cmmunity. See appendix B fr suggested messaging. Making available the B.C. HealthLink fact sheet entitled Blue-green Algae (Cyanbacteria) Blms t prvide cmmunities with infrmatin.. It is available nline at Any beach clsure shuld remain in effect until tw cnsecutive water samples are tested and cnfirmed t be less than 20 µg/l fr ttal micrcystins. Ntify the lcal water supply peratr that txins have been fund in the area. 7 Rdriguez, R. Evaluatin f Field Test Kits t Detect Micrcystins. Envirnmental Prtectin Agency, Available nline at

11 Page 11 PART B: Decisin Prtcls fr Cyanbacteria Txins Take any ther actins recmmended by the health authrity.

12 Page 12 PART B: Decisin Prtcls fr Cyanbacteria Txins APPENDIX A: CYANOBACTERIA PREPARATION CHECKLIST AND SAMPLE CONTACT LIST Cyanbacterial Blm Preparatin Checklist Preparatin is key t an effective respnse t cyanbacterial blms. Establishing relatinships with ther agencies and practising cllecting and analyzing samples are imprtant. Water suppliers and/r lcal gvernments shuld establish a plan fr recreatinal and drinking water surces that may be vulnerable t cyanbacterial blms, befre the anticipated blm seasn. This plan shuld lay ut what t d in case a cyanbacterial blm is visually detected in the water surce. It shuld: Identify agencies respnsible fr sampling (establish clear respnsibility fr water surces requiring sampling). Describe the sampling strategy (parameters, frequency, timing, lcatins) t be fllwed fr the duratin f the blm with respect t bth rutine sampling and resampling when micrcystins are detected. Identify the analytical labratry r labratries that can d micrcystin analysis. Ensure that agreement(s) and prtcl(s) are in place with lab(s) fr receiving and prcessing samples in a timely manner, and fr cmmunicating results frm the lab t the apprpriate cntact peple. Outline individual respnsibilities fr hw samples will be cllected and delivered t the labratry. Specify the methd(s) f micrcystin detectin/analysis that can be used. Identify the apprpriate cntact peple t receive the results frm the lab and wh they must ntify if micrcystins are detected. Identify which authrity r authrities are respnsible t decide further ntificatins and actins. Identify which authrity will take the lead rle in ntifying cmmunities and ther apprpriate agencies r authrities. Set ut a cmmunicatins plan describing the circumstances and target grups fr ntificatins, including when an advisry is issued r rescinded. Include sample messages and Qs & As t deal with different situatins (e.g., micrcystins level abve guideline, micrcystins detected belw guideline level but still f cncern fr infants) and prvide clear guidance t the public. Identify any crrective actins (e.g., treatment adjustments) and the triggers fr such actins. Sample Cntact List f Relevant Agencies Organizatin Rle Cntact Name Phne Health Authrity Water Supplier ME Lcal Gvernment

13 Page 13 PART B: Decisin Prtcls fr Cyanbacteria Txins Labratry Media

14 Page 14 PART B: Decisin Prtcls fr Cyanbacteria Txins APPENDIX B: SUGGESTED MESSAGING Micrcystins Detected in Drinking Water Ntice: D Nt Use Water fr Recnstituting Infant Frmula Use the frmat f appendix 13 f the Drinking Water Officers Guide. Suggested Messaging This ntice is being issued because blms f blue-green algae (cyanbacteria) have been detected in the water supply. The Drinking Water Officer, in cnsultatin with the Medical Health Officer, advises that the seasnal maximum acceptable cncentratin f mg/l (1.5 μg/l) has nt been exceeded, and there is n reasn fr a health warning fr the general ppulatin, including yung children. Hwever, because f the increased expsure f infants relative t bdy weight, anther suitable surce f drinking water (e.g., bttled water) shuld be used t recnstitute infant frmula. D Nt Use Ntice Ntice: D Nt Use Water Use the frmat f appendix 13 f the Drinking Water Officers Guide Suggested Messaging This ntice is being issued because blms f blue-green algae (cyanbacteria) have been detected in the water supply, and the seasnal maximum acceptable cncentratin f mg/l (1.5 μg/l) has been exceeded. Cnsumers shuld seek ther supplies f safe drinking water. Biling is nt effective in reducing r remving these txins, althugh sme pint-f-use devices may be effective. Dialysis treatment units in the cmmunity shuld als be ntified, especially if it is a first-time ccurrence fr blms n this supply. A HealthLinkBC fact sheet entitled Blue-green Algae (Cyanbacteria) Blms is available nline at Recreatinal Water Ntice: Beach Clsed, Issued by: Suggested Messaging: This ntice is being issued because blms f blue-green algae (cyanbacteria) have been detected in the water supply, and the recmmended Health Canada guideline f 20µg/L fr recreatinal water has been exceeded. Expsure t blue-green algae may cause nausea, vmiting, diarrhea and/r fever in humans and pets. Peple and pets shuld nt drink r swim in the water until further ntice. Anyne wh cmes in cntact with blue-green algae shuld rinse ff with fresh water.