wwwelseviercomlocatewasman

Waste Management 27 (2007) 792ndash801

Comparative analysis of hazardous household waste in twoMexican regions

Otoniel Buenrostro Delgado a Sara Ojeda-Benıtez b Liliana Marquez-Benavides a

a Instituto de Investigaciones sobre los Recursos Naturales (INIRENA)Research Centre for Natural Resources Studies Universidad Michoacana

de San Nicolas de Hidalgo Apartado Postal 12 CP 58190 Admon de Leon Romero No 413-A Morelia Michoacan Mexicob Instituto de IngenierıaEngineering Institute Universidad Autonoma de Baja CaliforniaAutonomous University of Baja California Blvd Benito Juarez y

Calle de la Normal SN Col Insurgentes Este 21280 Mexicali BC Mexico

Accepted 30 March 2006Available online 3 July 2006

Abstract

Household hazardous waste (HHW) generation in two Mexican regions was examined a northern region (bordering with the USA)and a central region The aim of this work was to determine the dynamics of solid waste generation and to be able to compare the resultsof both regions regarding consumption patterns and solid waste generation rates

In the northern region household solid waste was analysed quantitatively In order to perform this analysis the population was cat-egorized into three socioeconomic strata (lower middle upper)

Waste characterization revealed the presence of products that give origin to household hazardous waste In the northern region (Mex-icali city) household hazardous waste comprised 37 of municipal solid waste the largest categories in this fraction were home careproducts (292) cleaning products (195) and batteries and electronic equipment (157) In the central region HHW comprised103 of municipal solid waste the main categories in this fraction were represented by cleaning products (39) self care products(273) and insecticides (144)

In Mexicali the socioeconomic study demonstrated that the production of HHW is independent of the income level Furthermore thecomposition of the solid waste stream in both regions suggested the influence of another set of variables such as local climate migrationpatterns and marketing coverage Further research is needed in order to establish the effect of low quantities of HHW upon the envi-ronment and public health 2006 Elsevier Ltd All rights reserved

1 Introduction

Mexico is facing acute environmental and public healthdeterioration processes Hazardous waste (HW) produc-tion is considered to represent one of the main causesMoreover the growing modernization of the economyentailing a higher goods and services demand increasesthe quantity of hazardous waste HW may be generatedfrom residential and non-residential sources hence the

0956-053X$ - see front matter 2006 Elsevier Ltd All rights reserved

doi101016jwasman200603022

Abbreviations CB Cuitzeo Basin HHW household hazardous wasteMSW municipal sold waste HMIS hazardous materials identificationsystem HW hazardous waste

Corresponding author Tel +52 443 3272351 fax +52 443 3272350E-mail addresses otonielbzeusumichmx (OB Delgado) sojedab

uabcmx (S Ojeda-Benıtez)

need to study the amount and categories of this type ofwaste This information is fundamental to the design ofappropriate management strategies to avoid current mix-ing and codisposal with non-hazardous waste Howeverthe variety of products and the heterogeneity of sourcesmake the quantification of this type of waste difficult Thusthe characterization of containers packaging and wrap-ping materials of products that contained hazardous prod-ucts by composition might be used as an indicator toestimate the amount of hazardous waste mixed and dis-posed with the municipal solid waste

There are items used regularly in houses trade centersadministrative centers and institutions such as cleaningproducts self care products medicines home care productsautomotive maintenance products electronic equipment

1 CRETIB CODE Identifies corrosive reactive explosive toxic flam-mable and biologic-infectious characteristics

OB Delgado et al Waste Management 27 (2007) 792ndash801 793

and general maintenance products for machinery Theforementioned types of products are formulated with sub-stances that by themselves or when reacting with othersproduce additional compounds that when attaining certainconcentration levels might be capable of causing severeenvironmental and public health damage

In developing countries one of the problems with dailyhousehold products is that their chemical formulation islargely unknown both quantitatively and qualitatively Itis reasonable to expect that the chemical brew producedin a landfill matrix is altogether difficult to stabilize andable to produce substances with stronger damaging effectsMoreover in developing countries the synergistic effect ofmixtures of HW in the environment occurs without theawareness of local authorities since in general legislationdoes not consider separate solid waste disposal Mexicanlegislation considers as minimal the amount of householdhazardous waste generated nonetheless the cumulativeand synergistic effect of containers and packaging contain-ing remnants of HW are well able to exert a negativeimpact in landfills and open dumps A chronic effect shouldbe expected and measures are urgent

In Mexico open dumps are common place and pollutedsites are rampant across the country It is well known thatpluvial water and the water from biological breakdown orwater already contained in the solid waste leaches chemi-cals suspended solids and the like and carry a heavyorganic load to underground streams The leachate con-tains dissolved or suspended components originated inthe waste matrix Uncontrolled leachate migration fluxesdownwards and in addition to unpredictable concentra-tion levels is capable of producing permanent damage tothe public health water soil flora and fauna (Ejlertssonet al 2003)

11 Discussion on the topic of hazardousness of waste and

the confusion on the meaning of lsquolsquocontaminantrsquorsquo and

lsquolsquohazardousrsquorsquo

There is a wide-reaching discussion about the name andcharacteristics that should be applied to categorize house-hold hazardous waste (HHW) The clarification of thistopic is essential to determine suitable solid waste manage-ment strategies When discussing the term lsquolsquocontaminantrsquorsquoRushbrook and Pugh (1999) stated that contaminant wasteincludes a broad range of products considered hazardousfor a variety of factors one of them being the toxicitygrade where the cumulative effects of subproducts areexerted upon living organisms On the other hand Rest-repo et al (1991) suggests a categorization stating thatlsquolsquo contaminant waste originate from residues of explo-sive corrosive and radioactive productsrsquorsquo Restrepo andcoworkers (1991) estimate as contaminants paints insecti-cides lubricants etc mainly based in the amount of rem-nant disposed

In the USA the Environmental Protection Agency(USEPA) classifies as contaminants residues of domestic

use house care products garden and automotive mainte-nance and medicines (EPA 1993) Similarly Montanes(2001) classifies as contaminant waste those generatedfrom using cleaning products solvents aerosols pesticidespaints etc produced in small quantities in houses andthat may cause serious health problems due to toxic reac-tive corrosive and flammable characteristics

It is clear then that wastes are classified according to com-position and the effect that they exert on public health and tothe environment (Cortinas and Vega 1999 Merizalde et al2003 SEMARNAT 2001) In Mexico the legislationdefines a contaminant as lsquolsquoall matter and energy that in anyof their physical states and forms when incorporated or act-ing upon the atmosphere water soil flora or fauna or anynatural element that alters or modifies its composition andnatural conditionrsquorsquo (LEGEEPA 1988) In the same wayhazardous waste has been defined as lsquolsquothose wastes in anyphysical state that by any characteristic (corrosive toxicpoisonous reactive explosive flammable biological-infec-tious and irritant) represent a hazard to the ecologic or envi-ronment balancersquorsquo (LEGEEPA 1988)

In Mexico to categorize a waste as hazardous it has to beanalyzed according to the Mexican Official Norms (NOM)to determine if it presents certain characteristics or if it hasbeen mentioned in the hazardous waste list and to state thepermitted concentration limits Mexican regulation alsoincludes the lsquolsquoGeneral Law for Prevention and IntegratedSolid Waste Managementrsquorsquo a new legislation that may bethe access to include HHW based on the evidence of its haz-ardousness and risks involved (SEMARNAT 2003)

Hence a technical problem the categorization of a haz-ardous waste based on its hazardousness characteristicscan be misleading or a semantic problem Contaminant isan adjective and a noun that in general terms refers tothe lsquolsquoagentrsquorsquo that modifies or alters a condition and pro-duces an environmental impact (contamination) On theother hand the word hazardous is also a noun and anadjective but it denotes a characteristic It might be con-fusing when referring to a solid waste as a contaminantbased on the amount to treat or dispose because bothterms (residue and contaminant) are agents that producean alteration on the environment

Finally when referring to domestic solid waste it mightbe useful to clearly designate it as hazardous instead ofmerely a contaminant This designation should be pre-sented especially after the waste has undergone physico-chemical and biological degradation and fits the criteriaestablished by the CRETIB1 code

12 Variables that influence household hazardous waste

generation

The consumption of goods and products lead to thegeneration of HHW This condition is influenced by

794 OB Delgado et al Waste Management 27 (2007) 792ndash801

socioeconomic variables such as technological develop-ment (Galdames 2000) Income level determines the capac-ity of buying and the choice of brands and products suchas cleaning and maintenance products Similarly educationlevel influences the choice of purchasing specific productssuch as books and leisure activities Other variables suchas the weather and the season are known to influencethe purchasing of insecticides (Ojeda 1999 Consoni2002 Buenrostro and Israde 2003) The overall effect ofthe mentioned variables creates a complex mixture thatreflects new consumption patterns and lifestyles both con-tributing to increase the use of products that lead to thegeneration of HHW especially in developing countries

Concerning HHW generation Gaxiola (2003) reportedthat Mexicali City produced 185ndash326 tonnes HHWdayThe author pointed out the influence of variables onHHW production He found that HHW production isinversely proportional to the income level the lowerincome stratum produced 32 of HHWper capitadaywhereas the middle and upper strata produced 26 and104 respectively On the other hand Restrepo et al(1991) carried out a comparative study of the HHW amongtwo areas in the United States (New Orleans Louisianaand Marin County California) and Mexico City Theyfound that even though the income level was higher inthe north American households the three areas revealedsimilar HHW generation percentages 035 for NewOrleans 04 for Marin County and 034 for MexicoCity

The aim of this work was to collect data in the field andto compare results from two HHW generation studies in

Fig 1 Northern Baja California in the border zone wi

Mexico seeking to find similarities andor discrepanciesin the determinant variables The results will be relevantto provide a basis for integrated solid waste management

13 Description of the study area

The present work studied two different Mexican regionsOne of the study cases represented an urban settlement andwas carried out in Mexicali city in Northern Baja Califor-nia bordering with the USA Mexicali city has a popula-tion of 765 thousand people which is 33 of the totalpopulation of the state (INEGI 2000) The second casewas a rural settlement located in the municipalities aroundCuitzeo Lake in Michoacan The area comprises 23municipalities and according to the population densitysix of them were selected Chucandiro Copandaro Zina-pecuaro Santa Ana Maya Querendaro and Charo Itwas thought that the chosen municipalities were as repre-sentative as possible of the Basin area Fig 1 shows thegeographic location of both states in Mexico

2 Materials and methods

This work was carried out in four phases

1 Selection of sampling areas according to income rangeof households

2 Survey study to determine socioeconomic parameters3 Solid waste generation analysis4 Hazardous waste characterization

th the USA and Michoacan state in central Mexico

OB Delgado et al Waste Management 27 (2007) 792ndash801 795

21 Selection of sampling areas according to dwellings

income range

Areas were selected according to a socioeconomic classi-fication This classification is defined by the National Insti-tute of Statistics and Geography (INEGI 2000) Thepopulation is divided into three socioeconomic strata alower stratum with an income up to US$90week a middlestratum with an income up to US$235week and an upperstratum with an income of at least US$360week Threerepresentative neighborhoods for each stratum wereselected

22 Survey study to determine socioeconomic parameters

After representative socioeconomic sectors were selectedamong the city population dwellings in each sector wereselected first at random but at the end only houses whosehomeowners agreed to participate were included in thisstudy The applied survey included aspects such as monthlyearnings type of employment education level of familyheads age sex and aspects of waste management

23 Solid waste generation analysis

In Mexicali a solid waste generation analysis was car-ried out during a 7-day period In the Cuitzeo Basin sixmunicipalities were sampled 1 day each Bin bags werehanded out to participants and then were collected dailyOnce bin bags were gathered from the area each bag wasindividually weighed and characterized The procedure tosort individual components was adapted from the MexicanOfficial Norm NOM-AA-22-1985 (SECOFI 1985) Thebin bag content was emptied in a shallow tray(50 middot 40 cm) and single components were categorized man-ually by placing them in a pre-weighed and appropriatelylabeled tray Categories and sub-categories correspondedto the format described elsewhere (Buenrostro et al

Table 1Household hazardous waste categories

Home cleaning Automotivemaintenance

Batteries Medicines

Laundry detergentpowder or liquid

Oil Car batteries Oral

Dishwashing detergentpowder or liquid

Antifreeze agents Batteries Injections

Laundry aids Brake fluid SyrupBleach Lubricants LotionFabric softener Windshield

wiper solutionSuppositories

Oven cleaners Transmissionfluid

Foodsupplements

Soap barsAll-purpose cleanersWood protectorsDrain openersAir fragrances

2001) Once each part was categorized each tray wasweighed taking care to note if the final sum correspondedto the total weight (kg) of the bin bag The procedure wasperformed for each individual bin bag

For each household the weight of solid waste was aver-aged throughout the whole period After that each valuewas re-averaged among households from a given stratumThe result indicated the average solid waste generationper dwelling per stratum (kgdwellingstratum)

24 Hazardous waste characterization

Parallel to the solid waste generation analysis packag-ing and containers of hazardous wastes were selected andsorted according to the classification proposed by Rest-repo et al (1991) HHW was classified according to eightcategories as shown in Table 1 After categorization eachgroup was weighed including the weight of the containersper product plus any product remaining inside the con-tainer In the case of Mexicali results from each fraction(containers only and product separately) are also avail-able but are presented elsewhere (Lozano 2004)

3 Results

31 Solid waste generation analysis

Solid waste generation analysis in Mexicali covered atotal of 174 dwellings allowing the recovery of 970 samples(7215 kg) during a 7-day period (Ojeda et al 2003) In thestate of Michoacan sampling was carried out for 290dwellings (426 kg) Table 2 compares the results of solidwaste subproducts found in Mexicali and in the CuitzeoBasin (CB) zone Both regions similarly show the organicfraction as the largest component

Values shown in Table 2 revealed the quantitative andqualitative differences in waste production according toeach region These variations come as a result of diverse

Biological-infectious

Gardening Self care Others

Dialysis Insecticides Cosmetics andbeauty products

Oil base paint

Latex gloves Pesticides Hair care Water base paint

Syringes Soil fertilizers Lotion SolventsCondoms Perfume Shoe polishGauzebandages

Deodorant Printer toner

Soap bar Photography material

Talcum powder CDKetone GlueTooth pasteAcrylic nails

Table 2Domestic solid waste composition in Mexicali city compared with the Cuitzeo Basin zone ( wet basis)

Subproduct Mexicali Cuitzeo Basin Subproduct Mexicali Cuitzeo Basin

Organics Paper and cardboard

Food waste 169 426 Newspaper 15 NDGarden waste 78 163 Magazines 04 NDAnimal faeces 038 04 Bond paper 02 01Wood 031 04 Paper 12 NDCow hide 014 005 Cardboard 79 175Plant fibre 015 08 Sanitary waste

Textiles 206 187 Paper 39 31Inorganics Diapers 17 41Metallic paper 10 01 Inerts

Paper and wax-coated cardboard 001 28 Dirt 10 21Plastic bags 06 ND Stones 02 02Plastic 167 113 Tiles and ceramic 005 06Rigid plastic 09 ND Construction debris 06 02Glass 17 45 Other residues

Non Ferrous material 10 12 Shoes 045 009Tins 66 02 Electric material 01 001Ferrous material 07 10 Others 228 46Foam 05 005Tetrapack packages 06 NDRubber 01 01Aluminium foil 005 ND

ND not determined

Table 3Socioeconomic characteristics of dwellings in the Mexicali area

Socioeconomicstratum

PopulationdensityNo inhabitantsdwelling

Inhabitants witha remuneratejobfamily

Weekly incomedwelling(US dollars)

Lower 518 265 90Middle 402 274 235Upper 379 192 360

796 OB Delgado et al Waste Management 27 (2007) 792ndash801

lifestyles and consumption and generation patterns (Bue-nrostro et al 2001 Buenrostro and Israde 2003 Buenrostroand Bocco 2003) Results showed that in the zone borderingthe USA (Mexicali) the percentage of food waste was only40 of that generated in the rural area (Cuitzeo Basin) Atthe same time Mexicali yielded a 9 increase in the packag-ing category (plastics polyethylene bags and tetrapackboxes) comparable to the consumption patterns of theneighboring country (USA) Additionally the quantity oftins in both streams showed an important disparity (66in Mexicali and 02 in the Cuitzeo Basin) suggesting thatMexicali has a stronger buying power andor a lower price incanned products probably obtained in the USA Oftenproducts packed in aluminum or tin cans are at least 30more expensive when compared with the same product thatcomes in a glass container soft drinks and beers being thebest example To confirm this situation the Cuitzeo wastestream contained almost three times the amount of glassfound in Mexicali pointing out that the use of glass as apackaging material still has predominance

Mexicali in not only highly urbanized its climate isextremely dry and hot whereas the Cuitzeo Basin is locatedin the countryside with a much more benign weather pat-tern Despite this both places are disposing similar quanti-ties of animal feces wood textiles toilette paper andstones On the other hand disposable diapers in Cuitzeowere found to be twice the amount found in the city inaccordance to the national tendency where the highestbirth rates belong to rural and lower-income populations

Socioeconomic indicators of studied households revealthat in Mexicali population density was inversely propor-tional to income (Table 3) similar to other Mexican

regions (Bernache et al 1998 Buenrostro et al 2001)The socioeconomic analysis carried out in Cuitzeo revealeda population density of 41 inhabitantsdwelling corrobo-rating the national tendency of income being inversely pro-portional to population density Additionally a strongmigratory phenomenon was observed as nearly every fam-ily has a member that is lsquolsquotrying luckrsquorsquo in the USA

4 Household hazardous waste (HHW) characterization

studies

41 Mexicali area

The analysis of packaging and containers of productsthat contain HHW yielded different results for each regionTable 4 shows HHW daily generation produced typicallyby a family in different socioeconomic strata It is interest-ing to point out that on average the three largest catego-ries of HHW were home maintenance products (292)home cleaning products (195) and batteries and electrod-omestics (157) HHW generation varied according to thesocioeconomic stratum For families with the lowest

Table 4Household hazardous waste found in solid waste from residential sources in Mexicali ( ww)

Hazardous waste (group product) Socioeconomic strata Total (northernregion)Lower Middle Upper

kg kg kg kg

Automotive 94 191 88 62 58 74 240 89Home maintenance 67 135 669 473 52 65 787 292Insecticides 12 25 21 15 03 04 37 14Home cleaning 92 186 192 135 244 30 9 527 195Medicines 35 71 55 39 13 8 174 228 84Self care 78 158 121 85 160 203 359 133Batteries and small home appliances 103 208 220 156 101 128 424 157Others 12 25 50 35 33 42 95 35Total (HW) 493 100 1415 100 790 100 2698 100

Total (municipal waste kg) 12874 36896 22385 72154a 383 383 352 372

a Referred to the total stream of MSW

OB Delgado et al Waste Management 27 (2007) 792ndash801 797

income the three largest categories were batteries andsmall home appliances (208) automotive maintenanceproducts (19) and home cleaning products (186) Inthe middle stratum the bulk of HHW (75) is the sumof home maintenance products (473) batteries andelectrodomestics (156) and home cleaning products(135) Yet the upper stratum is mainly represented byhome cleaning products (309) self care products(203) and medicines (174)

42 Cuitzeo Basin (CB) area

In the CB zone a total of 447 kg of HHW was foundthe mentioned amount represented 105 of the solid wastestream Non-residential sources yielded 295 kg in totalequivalent to 119 of the total solid waste produced bythis source

Table 5 shows the proportions of HHW found in each ofthe six studied municipalities On the whole the threemajor contributing categories were home cleaning products(39) self care products (273) and insecticides (144)

Table 5Household hazardous waste from residential sources in the Cuitzeo Basin are

Household hazardous waste (category) (ww)

1 2

Automotive maintenance 00 00Home maintenance 00 00Insecticides 00 00Home cleaning 155 585Medicines 687 148Self care 00 71Batteries and small home appliances 158 198Others 00 00

Total HHW (kg) 01 04Total MSW (kg) 477 573 HHW 023 073

1 Copandaro 2 Charo 3 Chucandiro 4 Querendaro 5 Santa Ana Mayaonly

However HHW generation varied across municipalitiesand all of them had at least one category where no wastewas detected

In the Cuitzeo Basin hazardous waste from residentialsources averaged 103 of the total solid waste generationstream However percentages of HHW in each municipal-ity are highly variable ranging from 023 to 166HHW generation in Mexicali was 372 of the solid wastestream 22 times of that obtained in the Cuitzeo Basin

Fig 2 shows the differences in the composition of ofHHW in both areas studied In Mexicali the largest frac-tion is represented by house maintenance products 10 timesthe amount found in the Cuitzeo fraction Even more signif-icant the bulk of the hazardous fraction in Cuitzeo (67) isrepresented by home cleaning and beauty or self care prod-ucts while the composition in Mexicali was distributedmore evenly It is important to point out that medicineswere represented by similar percentages in both regionsand that the only other component that is bulkier in theCuitzeo Basin are the insecticides probably explained bythe rural location and the nearby presence of a lake

a

Total

3 4 5 6

87 00 00 00 2800 84 00 00 21

376 82 05 02 143345 257 401 534 386110 00 72 119 9969 555 384 320 27111 23 139 26 5200 00 00 00 00

15 11 04 09 44875 750 632 948 4256166 152 065 091 103

6 Zinapecuaro Each category percentage refers to the fraction of HHW

Fig 2 Comparative figures of HHW in Cuitzeo and Mexicali areas (1)Home cleaning products (2) Self-care products (3) Insecticides (4)Medicines (5) Batteries (6) Automotive maintenance (7) House main-tenance (8) Others ( related to the fraction of HHW found in solid wastestream)

798 OB Delgado et al Waste Management 27 (2007) 792ndash801

5 Discussion

Results revealed that the share of HHW found in Mex-icali (urban settlement) was 37 of the total MSW streamwhereas the share in the CB (rural area) was on averageonly 103 Several statements should be clarified aboutthese results The method used takes into account theweight of packages wrappings and containers of hazard-ous products therefore it overestimates the contributingpercentages of HHW Nonetheless even when makingthe assumption that containers and packages hold less than5 of leftover product the presence of packages and con-tainers plus any remnant suggest an impact on the environ-ment Hence the presence of them in the MSW streamshould be taken into account by local authorities

Table 6 shows a list of several reports on the contribu-tion of HHW to the total waste stream Except for the Sta-nek et al (1987) report our findings were significantlyhigher than those from developed countries Differencesmight be due to diverse methodologies separation and col-lection processes Even more our results correspond onlyto waste originated from households (residential source)

Table 6Household hazardous waste concentration reports

Study of theMSW stream

Reference

Mexicali Mexico 37 This workCuitzeo Basin Mexico 103 This workTijuana BC Mexico 11 Luna (2002)Mexico DF 01ndash10 Rosas and

Gutierrez (1998)Argentina 10 Altolaguirre (2004)Albuquerque New Mexico USA 05 Dorian (1988)US 0ndash05 Reinhart (1993)Albuquerque New Mexico USA lt05 Freeman (1989)Massachussets USA 40 Stanek et al (1987)UK 0ndash10 Slack et al (2004)

whereas other authors refer to the total amount found inthe MSW stream

A second consideration is the need to recognize that theimpact of the resulting chemical mixture on the publichealth (or the environment) is difficult to establish withoutmore data and the availability of reliable risk assessmentmethods To overcome the difficulties several consider-ations need further research such as interactions synergis-tic and antagonistic effects (Guhl 1999 Sabater et al2001) in addition to the chemical nature and concentrationranges existing in a landfill Furthermore when consideringpublic health it is difficult to assign to each HHW type (ormixture) a representative value to denote the lsquolsquorisk poten-tialrsquorsquo The risk level due to the exposure to insecticides isclearly higher than the the exposure to self-care productseven though both categories apparently constitue a similarpercentage of the waste stream (Table 7) from Mexicaliand from the CB region

Insecticides or pesticides can be absorbed by the skindigestive and respiratory systems but the greater risk iscutaneous Their liposoluble nature makes them a serioushealth problem due to accumulation (Romero et al2000) In the meantime self-care products have a chemicalcomposition similar to detergents (Daughton and Ternes1999) The ingredients used in personal care products dis-play a potential harm as they are ubiquitous in the environ-ment and are directly exposed to the human bodySynthetic musks have been found in aquatic environmentsseemingly innocuously but prudence dictates that theiraccumulation in various organisms of several trophic levelsin the aquatic ecosystems is unacceptable and that this sit-uation should be ameliorated

As discussed before it is crucial to establish coherentlabels when referring to the hazardousness of waste andto be able to assess the health risk that vulnerable groups(scavengers waste collectors and the like) are facing How-ever this task is extremely intricate because of the hetero-geneous nature of the mixture and all of the processes thattake place inside the landfill matrix Nonetheless evenwhen the Mexican Legislation describes how to assess thehazardousness of materials (CRETIB code) only industrialsources are under obligation to do so In the case of HHWeven though they originate from hazardous materials thelegislation does not consider them as hazardous due tothe small concentrations per product In developed coun-tries the aforementioned does not apply There are some

Table 7Risk values for typical household products according to the HMIS

Product Health rating Flammability Reactivity

House maintenance 2 4 1Insecticides 4a 4 4Self care 0 1 0Cleaning 3 1 1

HMIS 0 minimal 1 slight 2 moderate 3 serious 4 severea Cancer risk

Fig 2 Comparative figures of HHW in Cuitzeo and Mexicali areas (1)Home cleaning products (2) Self-care products (3) Insecticides (4)Medicines (5) Batteries (6) Automotive maintenance (7) House main-tenance (8) Others ( related to the fraction of HHW found in solid wastestream)

798 OB Delgado et al Waste Management 27 (2007) 792ndash801

5 Discussion

Results revealed that the share of HHW found in Mex-icali (urban settlement) was 37 of the total MSW streamwhereas the share in the CB (rural area) was on averageonly 103 Several statements should be clarified aboutthese results The method used takes into account theweight of packages wrappings and containers of hazard-ous products therefore it overestimates the contributingpercentages of HHW Nonetheless even when makingthe assumption that containers and packages hold less than5 of leftover product the presence of packages and con-tainers plus any remnant suggest an impact on the environ-ment Hence the presence of them in the MSW streamshould be taken into account by local authorities

Table 6 shows a list of several reports on the contribu-tion of HHW to the total waste stream Except for the Sta-nek et al (1987) report our findings were significantlyhigher than those from developed countries Differencesmight be due to diverse methodologies separation and col-lection processes Even more our results correspond onlyto waste originated from households (residential source)

Table 6Household hazardous waste concentration reports

Study of theMSW stream

Reference

Mexicali Mexico 37 This workCuitzeo Basin Mexico 103 This workTijuana BC Mexico 11 Luna (2002)Mexico DF 01ndash10 Rosas and

Gutierrez (1998)Argentina 10 Altolaguirre (2004)Albuquerque New Mexico USA 05 Dorian (1988)US 0ndash05 Reinhart (1993)Albuquerque New Mexico USA lt05 Freeman (1989)Massachussets USA 40 Stanek et al (1987)UK 0ndash10 Slack et al (2004)

whereas other authors refer to the total amount found inthe MSW stream

A second consideration is the need to recognize that theimpact of the resulting chemical mixture on the publichealth (or the environment) is difficult to establish withoutmore data and the availability of reliable risk assessmentmethods To overcome the difficulties several consider-ations need further research such as interactions synergis-tic and antagonistic effects (Guhl 1999 Sabater et al2001) in addition to the chemical nature and concentrationranges existing in a landfill Furthermore when consideringpublic health it is difficult to assign to each HHW type (ormixture) a representative value to denote the lsquolsquorisk poten-tialrsquorsquo The risk level due to the exposure to insecticides isclearly higher than the the exposure to self-care productseven though both categories apparently constitue a similarpercentage of the waste stream (Table 7) from Mexicaliand from the CB region

Insecticides or pesticides can be absorbed by the skindigestive and respiratory systems but the greater risk iscutaneous Their liposoluble nature makes them a serioushealth problem due to accumulation (Romero et al2000) In the meantime self-care products have a chemicalcomposition similar to detergents (Daughton and Ternes1999) The ingredients used in personal care products dis-play a potential harm as they are ubiquitous in the environ-ment and are directly exposed to the human bodySynthetic musks have been found in aquatic environmentsseemingly innocuously but prudence dictates that theiraccumulation in various organisms of several trophic levelsin the aquatic ecosystems is unacceptable and that this sit-uation should be ameliorated

As discussed before it is crucial to establish coherentlabels when referring to the hazardousness of waste andto be able to assess the health risk that vulnerable groups(scavengers waste collectors and the like) are facing How-ever this task is extremely intricate because of the hetero-geneous nature of the mixture and all of the processes thattake place inside the landfill matrix Nonetheless evenwhen the Mexican Legislation describes how to assess thehazardousness of materials (CRETIB code) only industrialsources are under obligation to do so In the case of HHWeven though they originate from hazardous materials thelegislation does not consider them as hazardous due tothe small concentrations per product In developed coun-tries the aforementioned does not apply There are some

Table 7Risk values for typical household products according to the HMIS

Product Health rating Flammability Reactivity

House maintenance 2 4 1Insecticides 4a 4 4Self care 0 1 0Cleaning 3 1 1

HMIS 0 minimal 1 slight 2 moderate 3 serious 4 severea Cancer risk

OB Delgado et al Waste Management 27 (2007) 792ndash801 799

tools to solve one aspect of this problem by estimating val-ues of risk for individual products An example is the haz-ardous materials identification system (HMIS) whichprovides a format for hazard determinations by standard-izing the presentation of chemical information to estimatevalues of health risk flammability and reactivity Table 7shows typical values for individual products according tothe HMIS Even though the HMIS offers informationon a wide range of products the problem remains in thatthe effects due to mixtures cannot be recognized by thistool

It is of crucial importance to be able to recognize solidwaste composition when designing waste managementand disposal strategies and to decide about sanitary pub-lic health and environmental impact policies (Robinsonet al 2003) However in developing countries there is alarge void of reliable data concerning waste compositionmanagement and infrastructure thus the decision makingprocess often relies in generalization of non-local large-scale data (Buenrostro and Bocco 2003) An appropriateillustration would be the lack of knowledge of real quanti-ties and organic waste composition and then estimatingmethane emissions only on a theoretical basis (Smith andBogner 1997)

Moreover the generation analyses in the Cuitzeo Basinrevealed that in the municipalities studied income is repre-sented homogeneously in the region but individual com-munities consume different products This might beexplained by external factors such as migration patternsFamilies or individuals make their way back and forth tothe USA and in the process become influenced by urbanlifestyles and exposed to advertising media An additionalfactor might be the education level causing the influenceof massive means of communication to be a strong influ-ence when consuming or using goods (Featherstone1991) Data extracted from the survey in the Cuitzeo Basinshowed that families regularly have at least one member inthe USA otherwise studying or working in nearby citiesconfirming the concept that migration plays a key role inregional consumer patterns (Buenrostro and Israde2003) Similarly in Mexicali it was commonly observedthat disposed products were made or originated in theUSA

On the other hand even though in the CB there is a pre-dominant lower income population compared to Mexicalithe fact that the presence of disposable diapers is larger inCuitzeo confirms similar reports (Buenrostro et al 2001)Disposable diapers have moved from an exclusive itemfrom a wealthy sector to a basic need item and confirmsthe INEGI report (2000) that birth rates in Mexico arehigher in rural areas

In Mexicali the concentration of HHW found wasgreater than in the CB region confirming the influence ofincome upon consuming products that originate that typeof waste However climate and migratory phenomenaare variables independent of income that determine theconsumerism of certain products to fulfill new basic needs

such as the use of diapers or insecticides in Cuitzeo Theuse of self care products was similar in the two regionsstudied showing that the marketing influence has modifiedregional consuming patterns due to new lifestyles expo-sure The presence of cheaper brands or smaller productpresentation containers was detected in the lower incomestratum and in the CB area indicating the growing influ-ence of marketing above income or climate

Additionally the organic fraction differed according tothe region studied The explanation for this may be dueto the influence from urban and rural patterns whereasthe difference in the rest of the waste stream may possiblybe a result of separate geographic locations Mexicali beinga border zone

In Mexicali the differences among the three strata werean indication of lifestyles and of the relationship betweensolid waste generation rates and income Seemingly thelower stratum is not able to carry out bulk purchases con-firmed by the notable presence of small containers andbudget batteries that although they are cheaper usuallydo not comply with minimal quality standards and haveshorter useful lives Something similar was observed withelectrodomestics that in addition to being refurbishedand second hand products they turn into disposable mate-rial sooner On the other hand the upper stratum includedas main categories self care products and medicines con-firming the economic means of this sector The HHW sam-ples obtained were 25 (lower) 130 (middle) and 348(upper) kgday however the environmental and publichealth risk is not represented entirely by the weight butby the specific properties of the resultant mixture (corro-sive flammable irritant and poisonous) and the effect ofits co-disposal with MSW

It is of crucial importance to start running programmesto separate hazardous domestic waste from the MSWstream as it is known that HHW might have a detrimentaleffect on the MSW degradation process (Ejlertsson et al2003) In Mexico a rapid evolution of open dumps to san-itary landfills is taking place (Robinson et al 2003) andthe production of greenhouse gases (CH4 and CO2) shouldbe controlled In addition organic pollutants coming frompaints plastics pesticides solvents and the like undergo arange of biotic and abiotic processes These reactions pro-duce organic and inorganic compounds in the liquid andgaseous phases of the anaerobic decomposition and affectnot only MSW mineralization (Ejlertsson et al 2003) butthe atmosphere and public health (Oman and Hynning1993)

Domestic HW represented by the mentioned contain-ers contributes to the environment with chemical sub-stances but specific formulations or quantities areunknown and so it is the synergistic effect they producewhen co-disposed The studied regions lack sustainableprogrammes to lessen HW generation or to manage ithence it might be more feasible to make a firstapproach by establishing collection centres Neverthelessalthough source separation is a fairly cheap strategy its

800 OB Delgado et al Waste Management 27 (2007) 792ndash801

implementation in the Cuitzeo Basin is difficult because ofa mixture of urban semi urban and rural waste the formerlacking even a proper collection system because of poor ornon-existant means of communication

Packaging and containers of HHW found in the twoMexican regions may at first sight not represent a seriousproblem as concentrations were 37 and 17 for Mexi-cali and the Cuitzeo Basin respectively However obtainedresults offer a platform to calculate HW production in opendumps and landfills in Mexico Because MSW amounts toseveral thousand tonnes per day in the country it is easy tosee HW production as a problem that has to be addressedin the short or medium term

6 Conclusions

1 HHW concentrations of 37 and 17 were detected in

the northern region (Mexicali) and in the CB arearespectively These percentages correspond to the shareof the total municipal solid waste stream

2 The study in Mexicali confirmed that income is inverselyproportional to the production of HHW

3 Significant differences in the HHW composition werefound suggesting the influence of a complex range ofvariables eg climate migratory phenomena market-ing etc

4 In Mexicali the largest HHW categories detected werehome maintenance products (292) cleaning products(195) and batteries and electrodomestics (157) Inthe Cuitzeo area the main categories were representedby cleaning products (39) self care products (273)and insecticides (144)

References

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Ejlertsson J Karlsson A Lagerkvist A Hjertberg T Svensson B2003 Effects of co-disposal of wastes containing organic pollutantswith municipal solid waste-a landfill simulation reactor studyAdvances in Environmental Research 7 949ndash960

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Freeman HM (Ed) 1989 Standard Handbook of Hazardous WasteTreatment and Disposal McGraw-Hill Book Co New York NYUSA

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Guhl W 1999 Safety evaluation of detergent formulations relevant tothe environment Tenside Surfantacs and Detergents 36 (6) 360ndash363

HMIS Implementation Manual JJ Keller and Associates Inc 3003 WBreezwood lane PO Box 368 WI USA Available fromltwwwjjkellercomgt

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LEGEEPA (Ley General del Equilibrio Ecologico y Proteccion alAmbienteGeneral Law for Ecological Equilibrium and Environmen-tal Protection) 1988 Official Federal Newspaper 28 of January of1988 completes applied reform 13 of June of 2003 (in Spanish)Available from ltwwweconomia-leyesyreglamentosgobmxgt

Lozano OG 2004 Generacion de Desechos Domesticos Contaminantesen la Familia y su Diferenciacion por Estrato Socioeconomico(Generation of Polluting Domestic Waste in the Family and itsdifferentiation by Socioeconomic Strata) Tesis de Maestrıa enSistemas Universidad Autonoma de Baja California Mexico 127 p

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Oman C Hynning P 1993 Identification of organic compounds inmunicipal landfill leachates Environmental Pollution 80 265ndash271

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Reinhart DR 1993 A review of recent studies on the sources ofhazardous compounds emitted from solid waste landfills a USexperience Waste Management and Research 11 257ndash268

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Rosas A Gutierrez C 1998 Estudio de Generacion de ResiduosPeligrosos Domesticos en una Zona Habitacional (Study of HazardousDomestic Wastes in a Neighborhood) Facultad de IngenierıaUniversidad Nacional Autonoma de Mexico

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SECOFI (Secretarıa de Comercio y Fomento Industrial)1985Relacion deNormas Oficiales Mexicanas Aprobadas por el Comite de Proteccional Ambiente-Contaminacion del suelo Mexico 104 pp

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Slack RJ Gronow JR Voulvoulis N 2004 Hazardous componentsof household waste Critical Reviews in Environmental Science andTechnology 34 419ndash445

Smith K Bogner J 1997 Measurement and modelling of methanefluxes from landfills IGACtivities Newsletter No 10 September

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US EPA 1993 Options for Reducing Methane Emissions InternationallyEPA 430--93-006 US Environmental Protection Agency July