Table 1
Actual Guidelines and Standards for Arsenic and Fluoride in Water, Food, Dentifrice, and Soil.
| Water | |||
|---|---|---|---|
| Toxicant | Guideline, Criteria (year of evaluation) | Value mg/L | Ref |
| Arsenic | Drinking water quality (2004) | 0.01 | WHO, 2011 [5] |
| Drinking water quality (2000) | 0.025 | SSA, 2000 [6] | |
| MCL (2002) | 0.01 | EPA, 2002 [7] | |
| Fluoride | MCL, Drinking water (2003) SMCL, Drinking water (2003) | 4.0 2.0 | EPA, 201 [8] |
| Drinking water quality (2004) | 1.5 | WHO, 2011 [5] | |
| Recommendation, Drinking water (2015) | 0.7 | US SHHS, 2015 [9] | |
| PL, fluoride in tap drinking water (2000) | 1.5 | SSA, 2000 [6] | |
| MPL, fluoride in bottled water (2015) | 0.7 | SSA, 2015 [10] | |
| ML, fluoride in bottled natural mineral water (2015) | 2.0 | SSA, 2015 [10] | |
| Food and toothpaste | |||
| Toxicant | Product, Guideline (year of evaluation) | Value mg/Kg | Ref |
| Arsenic | Action level for inorganic arsenic in apple juice (2011) | 0.01 | FDA, 2013 [11] |
| ML, salt, food grade (1985) | 0.5 | FAO/WHO, 2011 [12] | |
| ML, animal fats and vegetable oils (1981 and 1999). | 0.1 | FAO/WHO, 2011 [12] | |
| ML, polished rice, rice cereals (2014) | 0.2 | FAO/WHO, 2014 [13] | |
| Raw milk, pasteurized milk, sterilized milk, modified milk, fermented milk (2014) | 0.1 | MOPH, 2014 [14] | |
| Milk powders (2014) | 0.5 | MOPH, 2014 [14] | |
| Maximum Level of inorganic arsenic in infant rice-based products (2015) | 0.1 | US. 2015 [15] | |
| Action level for inorganic arsenic in infant rice cereals (2016) | 0.1 | FDA, 201 [16] | |
| Fluoride | ML, infant formula (1981) | 100 µg/100 kcal | FAO/WHO, 2007 [17] |
| MML, dentifrice for children (1996) | 850–1150 | FDA, 1996 [18] | |
| MML, salt (2010)a | 200–250 | SSA, 2010 [19] | |
| Soil | |||
| Toxicant | Guideline, Residential Use, Dry Weight (year of evaluation) | Value mg/Kg | Ref |
| Arsenic | Action level for As in contaminated soil (2004) | 22 | SEMARNAT, 2004 [20] |
| SGV (2009) | 32 | UKEA, 2009 [21] | |
| SQG (2007) | 12 | CCME, 2007 [22] | |
| Fluoride | Non-Establishedb | — | — |
[i] Abbreviations: MCL, maximum contamination level; MAL, maximum acceptable limit; ML, maximum level; RSL, regional screening. evel; THQ, target hazard quotient; SGV, soil guideline value; SQG, soil quality guideline; SSA, secretaria de salud; PL, permissible limit; MML, minimum and maximum level.
*Noncancer Child Hazard Index (HI) = 1.
aIn regions with fluoride concentration under 0.7 mg/L in drinking water.
bNo international or national guideline for soil are established. However, a mean concentration of 321 mg of fluoride per kilogram of soil has been reported as baseline criteria for soils [23].
Figure 1
Sites with presence of arsenic, fluoride, or its co-presence in well water in Mexico. Squares: arsenic ≥10 µg/L and fluoride ≤ 1.5 mg/L. Circles: localities where fluoride was ≥1.5 mg/L and arsenic <10 µg/L. Stars: localities with co-presence of arsenic and fluoride that exceeded the levels mentioned.
Table 2
Exposure Guidelines Values for Oral Exposure to Arsenic and Fluoride.
| Organization Ref | Guideline, Criteria (year of evaluation) | Study Description | Endpoint and Dose | Value | Experimental Doses (mg/Kg-day) |
|---|---|---|---|---|---|
| Arsenic Non-Cancer Endpoints | |||||
| US EPA Health Canada [66] | RfD (1993), TDI (2008) | Human cohort exposed to arsenic in drinking water | Hyperpigmentation, keratosis, and ar complications | 0.0003 mg/Kg-d | NOAEL: 0.0008 LOAEL: 0.014 |
| ATSDR [66] | MRL, chronic (2007) | Human cohort exposed to arsenic in drinking water | Dermal effects in a farming population | 0.0003 mg/Kg-d | NOAEL: 0.0008 |
| ATSDR [67] | MRL, acute (2007) | Human cohort exposed to contaminated soy sauce | Facial edema and gastrointestinal effects | 0.005 mg/Kg-d | LOAEL: 0.05 |
| US EPA [68] | Ingestion SL Child THQ = 1 (2017)* | _ | _ | 0.39 mg/Kg | _ |
| Arsenic Cancer Endpoints | |||||
| US EPA [66] | OSF (2007) | Human cohort exposed to arsenic in drinking water | Skin cancer | 1.5 mg/Kg-d | _ |
| Fluoride Non-Cancer Endpoints | |||||
| US EPA [69] | RfD, chronic (2010) | Cross-sectional study in children exposed to fluoride in drinking water | Severe dental fluorosis | 0.08 mg/Kg-d | NOAEL: 0.08 |
| ATSDR [70] | MRL, chronic (2003) | Cross-sectional study in adult Chinese population exposed to fluoride in drinking water | Risk of bone fractures | 0.05 mg/Kg-d | NOAEL: 0.15 |
| Health Canada [71] | TDI, chronic (2010) | Cross-sectional study in children exposed to fluoride from fluids and food | Moderate dental fluorosis | 0.105 mg/Kg-d | NOAEL: 0.105 |
| IOM [72] | UL, children under 8 years (1997) | Studies in children exposed to fluoride from dietary sources | Moderate dental fluorosis | 0.1 mg/Kg-d | LOAEL: 0.1 |
| UL, children ≥ 8 years (1997) | Early signs of skeletal fluorosis | 10 mg/day | NOAEL: 10 mg/day | ||
[i] Abbreviations: RfD, reference dose; TDI, total daily intake; MRL, minimum risk level; SL, screening level; THQ, target hazard quotient; OSF, oral slope factor; UL, upper intake; NOAEL, non-observable adverse effect level; LOAEL, low-observable adverse effect level.
* Non-Cancer Child Hazard Index (HI) = 1.
Table 3
Human Biomonitoring Data of Arsenic and Fluoride in Urine from Surveys in Children from Non-endemic/Reference Populations.
| Arsenic Biomonitoring | ||||||||
|---|---|---|---|---|---|---|---|---|
| Country/Ref | n | Age (years) | Total As | SumAs | iAs | MAs | DMAs | Urine Dilution Adj. |
| Canada, Health 2014–2015 [71] | 513 | 6–11 | 95th: 18 µg/L 50th: 5.5 µg/L | 95th: 1.4 µg/L 50th: <LOD | 95th: 14 µg/L 50th: 3.7 µg/L | None | ||
| Germany [85] | 1734 | 3–14 | 95th: 14 µg/L 50th: 4.5 µg/L | None | ||||
| Asaluyeh City, Iran [86] | 368 | 6–12 | C: 3.0 µg/gCr R: 2.2 µg/gCr | Urinary Creatinine | ||||
| Yucatán, México [87] | 36 | 6–9 | 7.5 µg/L | None | ||||
| Yucatán, México [88] | 107 | 6–9 | 2.9 µg/L | None | ||||
| Montevideo, Uruguay [89] | 327 | 5–9 | 9.9 µg/L | 1.0 µg/L | 0.9 µg/L | 1.9 µg/L | Specific Gravity | |
| Asturias, Gipuzkoa, Sabadell and Valencia, Spain [90] | 400 | 4 | 0.3 µg/L | 0.4 µg/L | 3.9 µg/L | Specific Gravity | ||
| Huelva, Spain [91] | 261 | 6–9 | 95th: 20.8 µg/gCr 50th: 3.4 µg/gCr | Urinary Creatinine | ||||
| US, NHANES 2011–2014 [92] | 397 | 6–12 | 95th: 17.8 µg/gCr 50th: 6.7 µg/gCr | 95th: 1.7 µg/gCr 50th: <LOD | 95th: 13.3µg/gCr 50th: 4.6µg/gCr | Urinary Creatinine | ||
| US, NHANES 2003–2008 [93] | 2323 | 6–17 | C: 8.9 µg/g Cr R: 5.5 µg/g Cr | C: 6.0 µg/gCr R: 3.6 µg/gCr | Urinary Creatinine | |||
| US, NHANES 2003–2004 [94] | 290 | 6–11 | 95th: 38.2 µg/gCr 50th: 7.1 µg/gCr | 95th: 14.7 µg/gCr 50th: 6.0 µg/gCr | 95th: 13.9µg/gCr 50th: 4.0µg/gCr | Urinary Creatinine | ||
| Fluoride Biomonitoring | ||||||||
| Country/Ref | n | Age/years | Source of Exposure | F Drinking water | F in urine | Urine Dilution Adj | ||
| Trinidad and Tobago 2001 [95] | 500 | 6–14 | NR | NR | Mean: 0.57 mg/L | None | ||
| Iztapalapa, Mexico City [96] | 205 | 4–5 11–12 | Various | 0.27 mg/L | Mean: 0.84 mg/L Mean: 0.58 mg/L | None | ||
| China 2008–2009 [97] | 26931 | 8–12 | Drinking Water | 0.54 mg/L | 50th: 0.90 mg/L 75th: 1.51 mg/L | None | ||
| Health Canada 2014–2015 [71] | 533 | 6–11 | Various | NR | 95th: 1.6 mg/L 50th: 0.47 mg/L | None | ||
| United Kingdom 2002–2014 [98] | 158 | 1.5–7 | Various | NR | Mean: 1.21 ± 0.6 mg/gCr | Urinary Creatinine | ||
[i] Abbreviations: SumAs, sum of arsenic; C, case; R, reference; F, fluoride; NR, non-reported
Notes: Total As includes all As species, organic and inorganic, whereas SumAs are: As(III) + As(V) + MAs + DMAs.
Table 4
Summary of Recent Human Biomonitoring Data and Health Effects Associated with Arsenic and Fluoride Exposure in Children from Endemic Regions in Mexico.
| Arsenic Biomonitoring | ||||||||
|---|---|---|---|---|---|---|---|---|
| Region/Ref | n | Age (years) | SumAs | iAs | MAs | DMAs | Urine Dilution Adj. | Health Effect(s) |
| Torreón, Coahuila [76] | 591 | 6–8 | 52.1 µg/L | 7.3 µg/L | 6.4 µg/L | 38.2 µg/L | None | Reducing As Methylation Capacity |
| Torreón, Coahuila [27] | 526 | 6–7 | 55.2 µg/L | 7.5 µg/L | 6.7 µg/L | 39.3 µg/L | None | Poor Behavior |
| Torreón, Coahuila [26] | 591 | 6–8 | 58.1 µg/L | 8.7 µg/L | 7.7 µg/L | 41.7 µg/L | None | Cognitive Deficits |
| Ciudad Juárez, Chihuahua [119] | 135 | 6–12 | 95th: 48.9 µg/gCr 50th: 17.6 µg/gCr | Urinary Creatinine | Biomonitoring | |||
| La Laguna, Durango [32] | 358 | 6–12 | H: 294.0 µg/L M: 143.7 µg/L L: 84.9 µg/L | H: 51.6 µg/L M: 23.9 µg/L L: 18.4 µg/L | H: 40.7 µg/L M: 19.6 µg/L L: 10.8 µg/L | H: 189.9 µg/L M: 96.2 µg/L L: 53.3 µg/L | None | Decreased Lung Function |
| Taxco, Guerrero [99] | 50 | 6–10 | 16.5 µg/L | None | Biomonitoring | |||
| Zimapán, Hidalgo [41] | 195 | 3–14 | 59.1 µg/L | 5.4 µg/L | 5.4 µg/L | 46.7 µg/L | None | Early Cardiovascular Effects |
| Zimapán, Hidalgo [100] | 87 | 6–10 | 194.6 µg/gCr | 20.4 µg/gCr | 30.1 µg/gCr | 144.1 µg/gCr | Urinary Creatinine | Oxidative Stress |
| Zimapán, Hidalgo [29] | 90 | 6–10 | 186.7 µg/L | 19.9 µg/L | 28.5 µg/L | 135.7 µg/L | None | Immunosu-ppression |
| Villa de la Paz and Morales, San Luis Potosí [40] | 84 | 6–12 | 26.44 µg/gCr | Urinary Creatinine | Epigenetic Imbalance | |||
| Villa de Reyes, San Luis Potosí [43] | 83 | 5–12 | 37.4 µg/L | Urinary Specific Gravity | Early Kidney Damage | |||
| Highlands and Centre regions, San Luis Potosí [34] | 85 | 4–11 | H: 44.5 µg/gCr M: 16.8 µg/gCr L: 12.8 µg/gCr | Urinary Creatinine | DNA Damage | |||
| Yaqui and Mayo Valleys, Sonora [101] | 165 | 6–12 | 30.9 µg/L | None | Biomonitoring | |||
| Fluoride Biomonitoring | ||||||||
| Country/Ref | n | Age (years) | Source of Exposure | F Drinking water | F in urine | Urine Dilution Adj. | Health Effect(s) | |
| Hermosillo, Sonora [102] | 31 | 8–9 | Drinking Water and Food | L: 0.54 mg/L M: 0.78 mg/L H: 2.77 mg/L | L: 0.93 mg/L M: 1.04 mg/L H: 3.1 mg/L | None | Risk Assessment | |
| L: Moctezuma, San Luis Potosí M: Salitral, San Luis Potosí H: 5 de Febrero, Durango [28] | 132 | 6–10 | Drinking Water | L: 0.8 mg/L M: 5.3 mg/L H: 9.4 mg/L | L: 1.8 mg/gCr M: 6.0 mg/gCr H: 5.5 mg/gCr | Urinary Creatinine | Cognitive Deficits | |
| Fluoride Biomonitoring | ||||||||
| Region/Ref | n | Age (years) | Source of Exposure | F Drinking water | F in urine | Urine Dilution Adj. | Health Effect(s) | |
| Soledad de Graciano Sánchez, San Luis Potosí [103] | 20 | 6–12 | Drinking Water | 0.67 mg/L | 1.94 mg/gCr | Urinary Creatinine | Increased Apoptosis in PBMC | |
| Villa de Ramos, San Luis Potosí [104] | 72 | 6–12 | Drinking Water | 2.3–5.4 mg/L | 1.0–8.0 mg/L | Specific Gravity | Inflammatory Expression Genes | |
| Salinas de Hidalgo, San Luis Potosí [105] | 111 | 6–12 | Driking Water | 4.54 mg/L | 3.14 ± 1.09 mg/L | Specific Gravity | Dental Fluorosis Prevalence (95%) | |
| Villa de Reyes, San Luis Potosí [43] | 83 | 5–12 | Drinking Water | 2.47 mg/L | 50th: 2.18 mg/L | None | None | |
[i] Abbreviations: SumAs, sum of arsenic; H, high; M, medium; L, low; NR, non-reported; PBMC, peripheral blood mononuclear cells.
Notes: Arsenic levels were quantified in urine samples. SumAs: As(III) + As(V) + MAs+ DMAs.