Artículo en PDF
How to cite
Complete issue
More information about this article
Journal's homepage in redalyc.org
Sistema de Información Científica
Red de Revistas Científicas de América Latina y el Caribe, España y Portugal
Rev. Int. Contam. Ambient. 21 (1) 17-22, 2005
FLUORIDE LEVELS IN MÉXICO CITY’S WATER SUPPLIES
Juan Carlos HERNÁNDEZ-GUERRERO
1
, Constantino LEDESMA-MONTES
1
, Maritza CARDIEL-
NIEVES
1
, Javier DE LA FUENTE-HERNÁNDEZ
2
and Dolores JIMÉNEZ-FARFÁN
1
1
Laboratorio de Inmunología, División de Estudios de Posgrado e Investigación. Facultad de Odontología, Uni-
versidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Coyoacán 04510, D.F., Méxi-
co. Correo electrónico: jcarlosh@servidor.unam.mx
2
Facultad de Odontología, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria,
Coyoacán 04510 D.F., México
(Recibido junio 2004, aceptado octubre 2004)
Key words: caries, fluoride, prevention, fluoridated water, water supplies
ABSTRACT
The purpose of this study was to assess the fluoride concentration in water supplies of
México City. Since Lerma-Cutzamala and Acuífero del Valle de México Water Supply
Systems distribute water to the México City’s Metropolitan Area (MCMA) we have
analyzed their water fluoride concentration using 44 different sampling wells from the
four geographical zones of the MCMA during 2002. The water sampling was monthly
made during one year. All collected data showed a mean fluoride concentration of 0.70
± 0.20 mg/L. Our results showed minor variability of fluoride concentrations in the water
available in México City. The fluoride content of the different analyzed zones showed
statistical differences. Although Mexican Health authorities have defined that fluoride
concentration in water should be from 0.70 to 1.50 mg/L, cases of dental fluorosis have
been reported in México City (Juárez-López
et al
. 2003). It is important to have a reliable
evaluation of fluoride concentration in México City’s natural water supplies prior to
implementing any caries-prevention program and to avoid novel cases of dental fluorosis.
Palabras clave: caries, fluoruro, prevención, agua fluorada, pozos de abastecimiento
RESUMEN
El propósito de este estudio fue conocer la concentración de fluoruros en los pozos de
agua de la ciudad de México. Debido a que los sistemas Lerma-Cutzamala y Acuífero del
Valle de México distribuyen el agua potable al Área Metropolitana de la ciudad de México
(AMCM), se analizó la concentración de fluoruros en 44 pozos de las cuatro zonas
geográficas del AMCM durante el 2002. El muestreo del agua se realizó cada mes durante
un año. Los datos obtenidos mostraron un promedio de concentración de fluoruros de
0.70±0.20 mg/L. Se encontraron diferencias estadísticamente significativas entre las con-
centraciones de fluoruros de las diferentes zonas analizadas. A pesar de que las
autoridades mexicanas del Sector Salud tienen bien definido que la concentración de
fluoruro en el agua potable es entre 0.70 mg/L y 1.5 mg/L, se han reportado casos de
fluorosis dental en la ciudad de México (Juárez-López
et al
. 2003). Es importante realizar
una evaluación confiable de la concentración de fluoruros en las fuentes naturales de
J.C. Hernández-Guerrero
et al.
18
agua potable de la ciudad de México antes de implementar cualquier programa de preven-
ción de caries e impedir la aparición de nuevos casos de fluorosis dental.
INTRODUCTION
Fluoride is an ion that appears in combination with
other elements forming fluorides in rocks and soil.
When water passes through and over the soil and
rock formations containing fluoride, it dissolves these
compounds resulting in small amounts of soluble fluo-
ride present in virtually all water sources (Evans
1997).
México City is located in the central part of
México and it is situated within a valley. Its altitude
is 2235 meters above the sea level. There are no
water fluoridation programs and fluoride from natu-
ral sources is in the drinking water. Due to fluoride
effectiveness in prevention of dental decay, several
countries have developed many alternatives to add
this ion in toothpastes, mouth rinses, tablets, foods
and drinks for children who live in not optimally–fluo-
ridated communities (Keyes and Englander 1975,
Levy 1986, Ismail 1994, Riordan 1999). As a result
of the increasing in fluoride ingestion it has been ob-
served an increased incidence of dental fluorosis
(Dean
et al
. 1942, Aasenden and Peebles 1974,
Pendrys
et al
. 1994, Wong and Gropen 1997, Clark
1998, Villa
et al
. 1998).
México City population receives naturally fluori-
dated water from two water systems known as
Lerma-Cutzamala and Acuífero del Valle de México.
To help the prevention of dental decay, in 1993 a salt
fluoridation program in México was established
(NOM-040-SSA-1-1993). Since 1993, some children
of México City have shown dental fluorosis lesions
(Juárez-López
et al
. 2003). This study was focused
to determine the fluoride content in México City water
supplies.
MATERIALS AND METHODS
The Lerma-Cutzamala and the Acuífero del Valle
de México water supply systems provide water to
México City. The supply systems have been divided
in four geographical zones by the México City’s gov-
ernment (
Fig. 1
). Forty four different wells distrib-
uted through the city were analyzed. Thirty three
wells are part of the Acuífero del Valle de México
and eleven wells compose the Lerma-Cutzamala
System. Water samples were directly collected from
the wells in plastic bottles. Which were washed sev-
eral times with distilled water before taking the
sample. All samples were stored at 4 ºC until their
analysis. Four water samples were taken per month,
per well (n = 48 samples per well).
Fluoride content in the water samples was quan-
tified using the fluoride selective ion method (Orion
Research 1991). A calibration curve was prepared
using standard solutions from 0.01 to 10 mg/L. From
each sample, 25 mL aliquots were taken and 1 mL
of TISAB (total ionic strength adjustment buffer)
was added. Readings were taken in mV by tripli-
cate and the fluoride concentrations were calcu-
lated with the calibration curve (r = 0.9999). Data
were analyzed with the SPSS software (version
11.0) applying the ANOVA and the Student’s t test.
RESULTS AND DISCUSSION
Fluoride concentration was measured during one
year and the results appear in
table 1
, the mean fluo-
ride concentration was 0.70 ± 0.20 mg/L (range from
0.26 to 1.38 mg/L). Fluoride content from the 44 ana-
lyzed wells showed significant statistical differences
(p < 0.001).
Data indicated that 59.1 % of the analyzed wells
(26 wells) had a mean fluoride concentration below
0.70 mg/L. Of them, water from 12 wells (27.3 %)
showed mean fluoride concentrations less than, but
close to, 0.70 mg/L. Water from the other 18 wells
(40.9 %) showed mean fluoride concentrations above
of 0.70 mg/L. Three wells showed values above 1.0
mg/L.
México City is divided in four geographical zones:
Northeast (NE), Northwest (NW), Southeast (SE)
and Southwest (SW). According to this division we
have found that the NW and SW zones showed the
widest range in the fluoride content followed by the
SE and NE zones. Significant statistical differences
(p < 0.001) were found when comparing fluoride
concentrations obtained from the four geographical
zones.
The monthly mean fluoride concentration in the
water samples of the individual wells did not show
statistically significant differences when they were
compared (
Table 2
).
We have analyzed fluoride concentrations dur-
FLUORIDE LEVELS IN MÉXICO CITY’S WATER SUPPLIES
19
ing the rain (May to October) and the drought peri-
ods (November to April). Mean fluoride concen-
tration during the rain period was 0.71 ± 0.20 mg/L
(range from 0.26 to 1.38 mg/L) and during the
drought period it was 0.69 ± 0.20 mg/L (range from
0.33 to 1.37 mg/L). No statistical differences were
found.
Mexican Normativity establishes that fluoride con-
centration should not exceed 1.5 mg/L (NOM-OF-
127-SSA1-1994). Our results showed that water
from all the analyzed wells were within this rule.
However, this normativity also establishes that when
water fluoride concentration is over 0.70 mg/L, the
use of fluoridated salt and fluoridated supplements
should be avoided (NOM-OF-040-SSA1-1993).
Our data, which indicate that NW and SW areas
of México City have wells with water fluoride con-
centrations above of 1.00 mg/L, are a possible cause
of the results from recent studies reporting dental
fluorosis cases in children living in these areas of
México City (Molina-Frechero
et al.
2000, Jiménez-
Farfán
et al
. 2001, Juárez-López
et al
. 2002, Juárez-
López
et al.
2003).
According to our results, México City’s water
wells showed variations in their fluoride concentra-
tions. This could be related with other associated
factors as temperature, the kind of soil, the altitude
or the depth of wells (Manji
et al
. 1986, Rwenyonyii
et al
. 1999). However, there were no differences
among the monthly concentrations and the seasons.
Other studies reported variations in the water fluo-
ride concentrations during the year (Richards
et al
.
1967). Although our results differ with them, it is
important to consider that the water consumption in-
creases during hot seasons (Lima and Cury 2003),
increasing the fluoride consumption by individuals
Lerma-Cutzamala
Water Supply System
Ajusco (23)
San Fernando Tlalpan (16)
Belizario Domínguez (17)
Miguel Hidalgo (18)
Peña Pobre (19)
Primavera
(15)
El Partidor
(27)
La Providencia
(26)
Bosques de Tetlameya (12)
Almoloya
(28)
Col. Olímpica (20)
Caracol (21)
C.U. (22)
El Venado
(29)
Viveros del Reloj (14)
Sta. Úrsula (13)
Irrigación (32)
Caída del Borracho
(41)
Las Palmas
(42)
San Joaquín
(43)
Periodistas (31)
Río San Joaquín (30)
Dolores
(44)
La Piruleta (34)
Lago Ginebra (35)
El Cartero
(24)
Sta. Lucía
(25)
Chapultepec Morelos (36)
Jardín Morelos (37)
Benjamín Franklin (38)
Viaducto (39)
Alamema Tacubaya (33)
Mártires de Tacubaya (40)
Agrícola Oriental (1)
Craudas (2)
San Sebastian (3)
Iztapalapa 2 (4)
Sta. Cruz Meyehualco 1 (5)
Sta. Cruz Meyehualco 2 (6)
S. 2 (7)
S. 4 (8)
Panteón San Lucas (9)
Reclusorio Sur 1 (10)
Reclusorio Sur 2 (11)
N
C
E
S
W
Fig. 1.
Acuífero del Valle de México Water Supply System is drawn as individual wells. Lerma-Cutzamala Water Supply System is
shown by a ramified, curved, thick line since it is a duct system
J.C. Hernández-Guerrero
et al.
20
(Horowitz
et al
. 1984, Levy
et al
. 1995, Kiritsy
et
al.
1996).
Recent studies in México have found different
fluoride concentrations in foods and beverages
(Maupomé-Carvantes
et al.
1995, Amato
et al
. 1997,
Loyola-Rodríguez
et al
. 1998, Alanís-Tavira
et al
.
1999). Unlike other countries, México does not have
studies to correlate the consumption of these prod-
ucts with the prevalence of dental fluorosis. The pres-
ence of dental fluorosis lesions could be related to
the consumption of diverse products naturally or ar-
tificially fluoridated. Up to the time that Mexican
Health authorities will establish adequate normativity
to regulate the distribution and supplementation of
fluoridated sources (drinking water, salt, supplements,
drinks, foods and so on), taking in mind the require-
ments of our population, the necessary consequence
will be that these prevention programs for dental
decay will be more effective and the rate of novel
dental fluorosis cases could decrease.
Zone
Mean
±
SD
Well
Mean
±
SD
Range
NE
0.77 ± 0.07
Agrícola Oriental No. 5
0.75
±
0.02
0.73 – 0.79
Gracidas
0.80
±
0.05
0.75 – 0.94
San Sebastián
0.69
±
0.03
0.63 – 0.73
SE
0.63 ± 0.14
Iztapalapa 2
0.86
±
0.05
0.77 – 0.91
Pozo Santa Cruz Meyehualco 1
0.79
±
0.03
0.71 – 0.84
Santa Cruz Meyehualco 2
0.68
±
0.07
0.61 – 0.88
Pozo S2
0.69
±
0.02
0.65 – 0.71
Pozo S4
0.56
±
0.04
0.51 – 0.60
Panteón San Lucas
0.69
±
0.03
0.67 – 0.79
Reclusorio Sur 1
0.76
±
0.11
0.42 – 0.89
Reclusorio Sur 2
0.53
±
0.05
0.47 – 0.67
Bosques de Tetlameya
0.40
±
0.14
0.33 – 0.82
Pozo Santa Úrsula 1
0.78
±
0.08
0.52 – 0.82
Viveros del Reloj
0.41
±
0.11
0.26 – 0.71
Tanque Primavera
0.69
±
0.03
0.60 – 0.71
San Fernando Tlalpan
0.62
±
0.04
0.52 – 0.71
SW
0.69
±
0.22
Belisario Domínguez
0.45
±
0.05
0.37 – 0.54
Miguel Hidalgo
0.52
±
0.04
0.47 – 0.59
Pozo Peña Pobre
0.41
±
0.02
0.38 – 0.47
Red Colonia Olímpica
0.69
±
0.03
0.62 – 0.72
Pozo Caracol
0.67
±
0.04
0.57 – 0.69
Pozo C.U.
0.64
±
0.05
0.53 – 0.69
Ajusco
0.74
±
0.11
0.40 – 0.82
Pozo El Cartero
0.68
±
0.02
0.65 – 0.72
Pozo Santa Lucía
0.74
±
0.02
0.68 – 0.77
Pozo Sifón La Providencia
0.59
±
0.02
0.55 – 0.61
Caída El Partidor
1.32
±
0.05
1.25 – 1.38
Almoloya
0.69
±
0.05
0.60 – 0.76
El Venado
0.06
±
0.02
0.57 – 0.65
Río San Joaquín
0.89
±
0.01
0.87 – 0.91
NW
0.76
±
0.23
Periodistas
0.77
±
0.02
0.73 – 0.81
Pozo Irrigación
1.29
±
0.08
1.04 – 1.37
Alameda Tacubaya
0.67
±
0.03
0.57 – 0.69
La Pirulera
0.78
±
0.02
0.75 – 0.81
Lago Ginebra
0.79
±
0.02
0.75 – 0.81
Chapultepec Morelos
0.79
±
0.02
0.72 – 0.81
Jardín Morelos
1.19
±
0.15
0.78 – 1.38
Pozo Benjamín Franklin
0.55
±
0.08
0.38 – 0.62
Pozo Viaducto
0.44
±
0.25
0.33 – 1.22
Mártires de Tacubaya
0.72
±
0.01
0.70 – 0.75
Caída del Borracho
0.78
±
0.02
0.75 – 0.81
Las Palmas
0.58
±
0.07
0.38 – 0.62
San Joaquín
0.67
±
0.02
0.63 – 0.69
Tanque Dolores
0.68
±
0.03
0.61 – 0.71
TABLE 1.
FLUORIDE CONCENTRATION (mg/L)
OF WATER SUPPLIES IN MÉXICO CITY. SAM-
PLING PERIOD: JANUARY-DECEMBER 2002
*
*
Each well was sampled four times each month (n = 48)
FLUORIDE LEVELS IN MÉXICO CITY’S WATER SUPPLIES
21
REFERENCES
Aasenden R. and Peebles T. (1974). Effects of fluoride
supplementation from birth on human deciduous and
permanent teeth. Arch. Oral. Biol. 19, 321-326.
Alanís-Tavira J., Rosas-Ceballos A. and Avendaño-
Nieves. (1999). Concentración de fluoruro en bebidas
envasadas. Pract. Odont. 20, 25-34.
Amato D., Maravilla A., García-Contreras F. and Paniagua
R. (1997). Soft drinks and health. Rev. Invest. Clin. 49,
387-395.
Clark D.C. (1998). Trends in prevalence of dental fluoro-
sis in North America. Comm. Dent Oral Epidemiol. 22,
148-152.
Dean H.T., Arnold F. and Elvove E. (1942). Domestic wa-
ters and dental caries. V. Additional studies of the re-
lation of fluoride domestic waters to dental caries ex-
perience in 4,425 white children aged 12-14 years in 13
cities in 4 states. Public Health Report 57, 1155-1161.
Evans R.W. (1997).The critical period of susceptibility to
enamel fluorosis in developing human maxillary and
mandibular teeth. J. Dent. Res. 76, 393-397.
Horowitz H., Dricoll W., Mayers R., Heifetz S.H. and
Kingman A. (1984). Excessive consumption of fluo-
ride while teeth are developing cause dental fluorosis.
(A new method for assessing the prevalence of dental
fluorosis –the tooth surface index of fluorosis-). J. Am.
Dent. Assoc. 109, 37-41.
Ismail A.I. (1994). Fluoride supplements: current effec-
tiveness, side effects, and recommendations. Comm.
Dent. Oral Epidemiol. 22, 164-172.
Jiménez-Farfán M.D., Sánchez-García S., Ledesma-Mon-
tes C., Molina-Frechero N. and Hernández-Guerrero
J.C. (2001). Fluorosis dental en niños radicados en el
suroeste de la ciudad de México. Rev. Mex. Pediatr.
68, 52-55.
Juárez-López L.A., Hernández–Guerrero J.C., Ledesma-
Montes C. and Galicia-Sosa A. (2002). Excreción
urinaria de flúor en niños de 11-12 años de edad
residentes en la zona oriente de la Ciudad de México.
Bol. Med. Hosp. Infan. Mex. 59, 356-364.
Juárez-López L.A., Hernández-Guerrero J.C., Jiménez-Farfán
D. and Ledesma-Montes C. (2003). Prevalencia de fluo-
rosis y caries dental en escolares de la ciudad de la
ciudad de México. Gaceta Med. Mex. 139, 221-225.
Keyes P. and Englander H.R. (1975). Fluoride therapy in
the treatment of dentomicrobial plaque diseases. J. Am.
Soc. Prev. Dent. 5, 16-21.
Kiritsy M.C., Levy S.M., Warren J.J., Guha–Chowdhury
N., Heilman J.R. and Marshall T. (1996). Assessing fluo-
ride concentrations of juices and juice–flavored drinks.
J. Am. Dent. Assoc. 127, 895–902.
Levy S. (1986). Expansion of the proper use systemic fluo-
ride supplements. J. Am. Dent. Assoc. 112, 30-34
Levy S.M., Kiritsy M.C. and Warren J.J. (1995). Sources of
fluoride intake in children. J. Pub. Health Dent. 55, 39–52.
Lima Y. and Cury X. (2003). Seasonal variation of fluoride
intake by children in a subtropical region. Caries Res.
37, 335-338.
Loyola-Rodríguez J.P., Pozos-Guillén A.J. and Hernández-
Guerrero J.C. (1998). Bebidas embotelladas como
fuentes adicionales de exposición a flúor. Salud Pública
Mex. 40, 438-441.
Manji F., Baelum V. and Fejerskov O. (1986) Fluoride, alti-
tude and dental fluorosis. Caries Res. 20, 473-480.
Maupomé-Cervantes G., Sánchez-Reyes V., Laguna-Ortega
S., Andrade-Delgado L. and Bonilla-Calderón J. (1995).
Patrón de consumo de refrescos en una población
mexicana. Salud Pública Mex. 37, 323-328.
Molina-Frechero N., Irigoyen M.A., Castañeda E.R.,
Hernández J.C. and Bologna R.E. (2000). Fluorosis
dental en la zona del Distrito Federal con baja con-
centración de flúor en agua. In: Generando cono-
cimientos. La investigación científica y humanística
en la UAM-Xochimilco (C. Cortéz-Ruiz, J. Reséndiz-
Téllez and M.A. Zepeda-Zepeda, Eds.). México, UAM-
X, pp. 341-345.
Orion Research (1991). Electrode instruction manual, USA.
Pendrys D., Katz R. and Morse D. (1994). Risk factors of
fluorosis in a fluoridated population. Am. J. Epidemiol.
140, 461-471.
Richards L.F., Westermoreland W.W., Tashiro M., McKay
C. and Morrison J. (1967). Determining optimum fluo-
ride levels for community water supplies in relation to
temperature. J. Am. Dent. Assoc. 74, 389-397.
Riordan P.J. (1999). Fluoride supplements for young chil-
dren: an analysis of the literature focusing on benefits
and risk. Comm. Dent. Oral Epidemiol. 27, 72-82.
Rwenyonyii C.M., Bjorvtn J.M., Birkeland J.M. and
Haugejorden O. (1999). Altitude as risk indicator of
Month
Mean
Range
January
0.70
±
0.21
0.33 to 1.37
February
0.70
±
0.19
0.34 to 1.31
March
0.70
±
0.21
0.33 to 1.37
April
0.70
±
0.20
0.33 to 1.37
May
0.70
±
0.20
0.26 to 1.25
June
0.71
±
0.20
0.41 to 1.33
July
0.71
±
0.20
0.38 to 1.29
August
0.72
±
0.21
0.40 to 1.33
September
0.72
±
0.21
0.40 to 1.38
October
0.71
±
0.21
0.37 to 1.31
November
0.71
±
0.21
0.33 to 1.33
December
0.68
±
0.21
0.33 to 1.29
TABLE 2.
MONTHLY MEAN FLUORIDE CONCENTRA-
TIONS (mg/L) IN WATER SAMPLES
J.C. Hernández-Guerrero
et al.
22
dental fluorosis in children residing in areas with 0.5
and 2.5 mg fluoride per liter in drinking water. Caries
Res. 33, 267-274.
Secretaría de Salud (1995). Norma Oficial Mexicana NOM-
040-SSA-1-1993. Sal yodatada y sal fluorada. Diario
Oficial de la Federación, México, marzo de 1995, pp.
12-27.
Secretaría de Salud (1996). Norma Oficial Mexicana NOM-
127-SSA1-1994. Salud ambiental. Agua para uso y
consumo humano. Límites permisibles de calidad y
tratamientos a que debe someterse el agua para su
potabilización. Diario Oficial de la Federación, México,
enero de 1996, pp. 41-46.
Villa A.E., Guerrero S., Icaza G., Villalobos J. and Anabalon
M. (1998). Dental fluorosis in Chilean children: evalu-
ation of risk factors. Comm. Dent. Oral Epidemiol. 26,
310-315.
Wong N.J. and Gropen A.M. (1997). Risk factors associ-
ated with fluorosis in monofluoride population in Nor-
way. Comm. Dent. Oral Epidemiol. 25, 396-401.
logo_pie_uaemex.mx