heavy metals contamination in davao region

8/8/2019 Heavy Metals Contamination in Davao Region

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HEAVY M ETALS CON TAM I N ATI ON I NDAVAO R EGI ON

Ed. B . P rant il la*and

Carmeli ta M art inez ***RECORD Foundation and School of Applied Economics, USEP**School of Government and Management, USEP



Introduction

The relevance of heavy metalscontamination in Davao Region toCaraga Region is due to the fact thatNaboc River, which drains the gold rusharea at Diwalwal, is a tributary of

Agusan River. The Diwalwal gold rusharea uses about 6 metric tons of mercury annually.



Objectives of the Study

Using available monitoring reports andstudies, present a consolidated reporton:The extent of heavy metalscontamination of rivers and lake inDavao Region.



Objectives (cont’d)

Extent of heavy metals contaminationof fish and shellfish in Davao Gulf andin Lake Leonard.Effects of mercury contamination inhuman population, andRecommends possible actions.



Sources of Heavy MetalsContamination in Davao Region

Mercury – mainly from gold processing:Estimated annual mercury consumption

by gold rush area:Diwalwal --- 5,724 kgs.Boringot ---- 720 kgs.Biasong ---- 600 kgs.Diat --------- 2,388 kgs.



Sources of heavy metalscontamination (cont’d)

Panganason ----- 588 kgs.Gumayan -------- 1,980 kgs.Bango ------------ 888 kgs.Lumanggang, Maco – 84 kgs.Lumanggang, Pantukan – 252 kgs.

Inopuan-Saravan -------- 300 kgs.Total annual Hg consumption = 13,524 kgs.

Source of Basic Data: MGB, DENR XI



Sources of heavy metalscontamination (cont’d)

Lead – possible sources are from thenatural deposits of this metal in rocksleached through weathering processand from small-scale mining.Cadmium – same as lead.



Extent of heavy metalscontamination in rivers and lake

Naboc River – A tributary of Agusan River,heavily contaminated with mercury. Water inall nine sampling stations reported mercury

contents much higher that standard set byDAO 34 for Class C water in 2006. Leadcontent of 5 out of 9 sampling stationsregistered lead content higher that standardset by DAO 34. Cadmium content belowcritical level for Class C water.



Extent of heavy metals contamination inrivers and lake (cont’d)

Kingking River – Discharges directly toDavao Gulf. Six (6) sampling stationsregistered mercury content higher that

the standard set by DAO 34 for Class Cwater in 2006. Cadmium is belowcritical level, but lead registered highlevel over the standard in 2004 for all 6sampling stations. Lead analysis is notavailable for 2006.




Hijo River – Mercury content of waterfrom 9 sampling stations exhibitedbelow critical level for Class C water in2005. No sediment study conducted.Lead content of water was very high in

sampling stations 4 to 9 in 2001 and in6 to 9 in 2003. Below critical level from2004 to 2005 in all sampling stations.




Matiao River – Water from onesampling station registered mercurycontent higher that the limit set by DAO34 in 2006. Cadmium content below thelimit, lead analysis is not available.




Batoto River – Mercury content of waterfrom 6 sampling stations exhibitedmercury content below the limit set byDAO 34. No analysis for lead andCadmium available.




Masara River – Water monitoringreports cover only lead and cadmium.Cadmium content was below the limitset by DAO 34. Lead content of waterfrom 7 stations in 2005 gave an

unambiguous result, i.e. they could behigher or lower than the limit set byDAO 34.




Manat River – the 2005 available reportshowed that cadmium, lead andmercury content of water from 6sampling stations were all below thelimits set by DAO 34.




Lake Leonard – water samples from 12stations revealed the following: Hgbelow critical level; Pb beyond criticallevel in 2001, and Cd beyond criticallevel for stations 3, 5, 7 and 10. Soil

samples registered Pb content beyondtolerable level in all stations; Cd instations 7, 8, 9, 10 and 12.




Lake Leonard (cont’d) – an analysis of fish captured in the lake in 2001showed lead, cadmium and coppercontents higher than the criticaltolerable limits (standard used was EU

guidelines for fish).



Mercury in Davao Coastal Waters(cont’d.)

The 1982 study (cont’d)Mercury levels in Fish – found mercurylevels in Tangigue; Barilis; Tulingan;and Diwit exceeded the 0.500 ppm limitset by WHO.



Mercury in Davao Coastal Waters(cont’d)

The 1982 study (cont’d):Mercury level in Shellfish – Hg level inshellfish caught in Tibungko (Anadaracepoides; Gafrarium tumidium;Terebralia sp.; Turbo sp.; Nerita sp.)

have mercury content higher than thelimit set by WHO.




Mercury levels in shellfish (cont’d) –shellfish (Tivela sp.) caught at Bucana,and shellfish (Haliotis sp.) caught atGodo registered mercury content higherthan the limit set by WHO.




The DOH XI study (2006):Examined fish samples from Davao delSur, Davao Oriental and Davao Citymarkets and found out that “talakitok;

“mayamaya”, “bariles” and “malasugue”

have methyl mercury content higherthan the allowable limit of 0.3 microgram per gram.



Mercury Levels in Human Population(cont’d)

The Maramba-Dablo study (cont’d):Examined 70 miners, field healthpersonnel and residents in Diwalwal,results of laboratory analysis showed 6respondents with blood mercury levels

greater than 20 ppb, and 3 respondentswith urinary mercury levels greater than50 ppb.



Mercury Levels in Human Population(cont’d)

The DOH XI study (2006)Total blood mercury level ranges from 3.51to 299.99 micro gram per liter with anaverage of 21.44 micro gram per liter.Forty-five individuals or 60% of thoseindividuals directly involved in gold miningwere found to have high levels of mercury

at more than 15 ug/L while three individualsor 12% of those with no direct exposurewere also found to have high levels of mercury at more than 15 ug/L.



Mercury in Pregnant Women

The Ramirez, et al studies (2000,2003): The study was conducted at Apokon, Tagum City. Observed that “the problem of exposure to Hg in thisarea is particularly serious for the

pregnant women because there are nobarriers to the transfer of Hg from themother to the fetus”



Mercury in Pregnant Women (cont’d)

The Ramirez, et al study (2000, 2003)(cont’d): “The prevalence of Hg in cord bloodwas significantly related to the prevalence in

the mothers' blood. Regression analysis of levels of Hg in cord blood showed asignificant relation to levels in mothers' blood

(.0001), prevalence in infants' hair (.0126),gestational age (GA) (.0091), and headcircumference (HC) (.0469)”



Mercury in Pregnant Women (cont’d)

The Ramirez, et al study (2000, 2003)(cont’d): The 2000 study concluded that “Adverse effects may not be evident atbirth but sub-clinical toxicity of the fetusis a possibility. Therefore, long-term

developmental and neurobehavioralassessments are needed”



Mercury in Pregnant Women(cont’d)

The Ramirez, et al follow-up 2003study:The study used 47 of the originalinfants from Tagum and 88 infants of the same age from Sarangani as

control. The tests used are: cognitiveadaptive test and clinical linguisticauditory milestone scale (CAT/CLAMS)




The Ramirez, et al follow-up 2003 study(cont’d): The following were found higher inthe control group compared to Tagum infants

(a) expressive language quotient; (b) CLAMS,and (c) Full-scale developmental quotient.Fifteen percent of Tagum infants had global

delay (full-scale developmental quotient).




The Ramirez, et al follow-up 2003 study(cont’d): The study concluded that “thatprenatal Hg exposure is correlated withlower scores in neuro-developmentalscreening, but more so in the linguistic

pathway. Other confounding factorscannot be eliminated”.



Recommendations (cont’d)

Eradication of illegal trade of mercuryin the region. Mercury could only beused by licensed users with thegovernment imposing strictcompliance with environmental laws

concerning the use of mercury.




The use of mercury in gold processing isprevalent only with small scale miners orartisanal miners. If the government will opt

therefore to maintain the operation of smallscale or artisanal mining, it should impose acondition that small scale or artisanal

miners should use an alternative goldextraction technology that does not involvemercury.



Recommendations (cont’d)The presence of high mercury level in the rivers of Compostela Valley province needs immediateattention, not only in controlling or completelystopping the use of mercury in the mining areas of

the province, but also to determine the extent of the damage suffered by the environment and theaffected population. Accordingly, appropriateremediation process should be undertaken by the

government including the compensation of thepopulation whose health have been compromisedor affected by mercury contamination.



Recommendations (cont’d)Government action on the presence of high levelsof mercury in certain species of fish caught inDavao Gulf is long overdue. This inaction of thegovernment may have very serious healthimplications because those fishes with high level of mercury are eaten by a large portion of the DavaoRegion population. It is therefore recommendedthat the government immediately warn the public

about the danger of eating Tangigue, Barilis,Tulingan, Diwit, Talakitok, Mayamaya, andMalasugui.



Recommendations (cont’d)It has been observed that the population at large isinadequately informed on the dangers of heavymetals pollution and in particular the effect of mercury on the health status of a person. It istherefore recommended that a broad-basedintensive information, education andcommunication program be formulated andimplemented by the local government units and

national government agencies, the academe andnon-government organizations in the region.




Include heavy metals as priorityparameter in calculating wastewaterdischarge fee.

heavy metals contamination in davao region

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