Nitrate and trace elements in municipal and bottled water in Spain

In vitro bioassays for monitoring drinking water quality of tap water, domestic filtration and bottled water

BACKGROUND

Location-specific patterns of regulated and non-regulated disinfection byproducts (DBPs) were detected in tap water samples of the Barcelona Metropolitan Area. However, it remains unclear if the detected DBPs together with undetected DPBs and organic micropollutants can lead to mixture effects in drinking water.

OBJECTIVE

To evaluate the neurotoxicity, oxidative stress response and cytotoxicity of 42 tap water samples, 6 treated with activated carbon filters, 5 with reverse osmosis and 9 bottled waters. To compare the measured effects of the extracts with the mixture effects predicted from the detected concentrations and the relative effect potencies of the detected DBPs using the mixture model of concentration addition.

METHODS

Mixtures of organic chemicals in water samples were enriched by solid phase extraction and tested for cytotoxicity and neurite outgrowth inhibition in the neuronal cell line SH-SY5Y and for cytotoxicity and oxidative stress response in the AREc32 assay.

RESULTS

Unenriched water did not trigger neurotoxicity or cytotoxicity. After up to 500-fold enrichment, few extracts showed cytotoxicity. Disinfected water showed low neurotoxicity at 20- to 300-fold enrichment and oxidative stress response at 8- to 140-fold enrichment. Non-regulated non-volatile DBPs, particularly (brominated) haloacetonitriles dominated the predicted mixture effects of the detected chemicals and predicted effects agreed with the measured effects. By hierarchical clustering we identified strong geographical patterns in the types of DPBs and their association with effects. Activated carbon filters did not show a consistent reduction of effects but domestic reverse osmosis filters decreased the effect to that of bottled water.

IMPACT STATEMENT

Bioassays are an important complement to chemical analysis of disinfection by-products (DBPs) in drinking water. Comparison of the measured oxidative stress response and mixture effects predicted from the detected chemicals and their relative effect potencies allowed the identification of the forcing agents for the mixture effects, which differed by location but were mainly non-regulated DBPs. This study demonstrates the relevance of non-regulated DBPs from a toxicological perspective. In vitro bioassays, in particular reporter gene assays for oxidative stress response that integrate different reactive toxicity pathways including genotoxicity, may therefore serve as sum parameters for drinking water quality assessment.

Lifetime exposure to brominated trihalomethanes in drinking water and swimming pool attendance are associated with chronic lymphocytic leukemia: a Multicase-Control Study in Spain (MCC-Spain)

BACKGROUND

Chronic lymphocytic leukemia (CLL) etiology is poorly understood, and carcinogenic chemicals in drinking and recreational water are candidates.

OBJECTIVE

To evaluate the association between drinking-water exposure to trihalomethanes (THMs) and nitrate as well as lifetime swimming pool attendance and CLL.

METHODS

During 2010-2013, hospital-based CLL cases and population-based controls were recruited in Spain, providing information on residential histories, type of water consumed and swimming pool attendance. Average THMs and nitrate levels in drinking water were linked to lifetime water consumption. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models.

RESULTS

Final samples for residential tap water analyses and swimming pool attendance analyses were 144 cases/1230 controls and 157 cases/1240 controls, respectively. Mean (SD) values for average lifetime residential brominated THMs and chloroform in tap water (μg/L), and ingested nitrate (mg/day) were 48.1 (35.6), 18.5 (6.7) and 13.7 (9.6) respectively in controls; and 72.9 (40.7), 17.9 (5.4), and 14.1 (8.8) in CLL cases. For each 10 μg/L increase of brominated THMs and chloroform lifetime-average levels, the ORs (95% CI) were 1.22 (1.14, 1.31) and 0.54 (0.34, 0.87), respectively. For each 5 mg/day increase of ingested nitrate, the OR of CLL was 0.91 (0.80, 1.04). The OR of lifetime pool users (vs. non-users) was 2.38 (1.61, 3.52). Upon performing annual frequency of attending pools analysis through categorization, the second and third categories showed an ORs of 2.36 (1.49, 3.72) and 2.40 (1.51, 3.83), respectively, and P-trend of 0.001.

IMPACT STATEMENT

This study identifies an association of long-term exposure to THMs in drinking water, at concentrations below the regulatory thresholds and WHO guidelines, and swimming pool attendance, with chronic lymphocytic leukemia (CLL). These unprecedented findings are highly relevant since CLL is an incurable cancer with still unknown etiology and because the widespread exposure to chlorination by-products that remain in drinking and recreational water worldwide. Despite the demonstrated carcinogenicity in animals of several chlorination by-products, little is known about their potential risks on human health. This study makes a significant contribution to the search for environmental factors involved in the etiology of CLL and to the evidence of the health impact of these high prevalent water contaminants.

Metabolomic Signatures of Exposure to Nitrate and Trihalomethanes in Drinking Water and Colorectal Cancer Risk in a Spanish Multicentric Study (MCC-Spain)

We investigated the metabolomic profile associated with exposure to trihalomethanes (THMs) and nitrate in drinking water and with colorectal cancer risk in 296 cases and 295 controls from the Multi Case-Control Spain project. Untargeted metabolomic analysis was conducted in blood samples using ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry. A variety of univariate and multivariate association analyses were conducted after data quality control, normalization, and imputation. Linear regression and partial least-squares analyses were conducted for chloroform, brominated THMs, total THMs, and nitrate among controls and for case-control status, together with a N-integration model discriminating colorectal cancer cases from controls through interrogation of correlations between the exposure variables and the metabolomic features. Results revealed a total of 568 metabolomic features associated with at least one water contaminant or colorectal cancer. Annotated metabolites and pathway analysis suggest a number of pathways as potentially involved in the link between exposure to these water contaminants and colorectal cancer, including nicotinamide, cytochrome P-450, and tyrosine metabolism. These findings provide insights into the underlying biological mechanisms and potential biomarkers associated with water contaminant exposure and colorectal cancer risk. Further research in this area is needed to better understand the causal relationship and the public health implications.

Long-Term Exposure to Nitrate and Trihalomethanes in Drinking Water and Prostate Cancer: A Multicase-Control Study in Spain (MCC-Spain)

BACKGROUND

Nitrate and trihalomethanes (THMs) in drinking water are widespread and are potential human carcinogens.

OBJECTIVE

We evaluated the association between drinking-water exposure to nitrate and THMs and prostate cancer.

METHODS

During the period 2008-2013, 697 hospital-based incident prostate cancer cases (97 aggressive tumors) and 927 population-based controls were recruited in Spain, providing information on residential histories and type of water consumed. Average nitrate and THMs levels in drinking water were linked with lifetime water consumption to calculate waterborne ingestion. Odds ratios (OR) and 95% confidence intervals (CI) were estimated using mixed models with recruitment area as random effect. Effect modification by tumor grade (Gleason score), age, education, lifestyle, and dietary factors was explored.

RESULTS

Mean (±standard deviation) adult lifetime waterborne ingested nitrate (milligrams per day), brominated (Br)-THMs (micrograms per day), and chloroform (micrograms per day) were 11.5 (±9.0), 20.7 (±32.4), and 15.1 (±14.7) in controls. Waterborne ingested nitrate >13.8 vs. <5.5mg/d was associated with an OR of 1.74 (95% CI: 1.19, 2.54) overall, and 2.78 (95% CI: 1.23, 6.27) for tumors with Gleason scores ≥8. Associations were higher in the youngest and those with lower intakes of fiber, fruit/vegetables, and vitamin C. Waterborne ingested THMs were not associated with prostate cancer. Residential tap water levels of Br-THMs and chloroform showed, respectively, inverse and positive associations with prostate cancer.

CONCLUSIONS

Findings suggest long-term waterborne ingested nitrate could be a risk factor of prostate cancer, particularly for aggressive tumors. High intakes of fiber, fruit/vegetables and vitamin C may lower this risk. Association with residential levels but not ingested chloroform/Br-THM may suggest inhalation and dermal routes could be relevant for prostate cancer. https://doi.org/10.1289/EHP11391.

Quantifying the nitrate levels in bottled water in New Zealand

OBJECTIVE

There is growing epidemiological evidence linking nitrate contamination to adverse health outcomes. Health concerns may drive consumers towards bottled water, however, nitrate levels in bottled water are not readily available.

METHODS

We tested water samples from the 10 most popular brands using a TriOS OPUS UV optical nitrate sensor.

RESULTS

Overall, all bottled water brands tested returned nitrate levels below 4.4 mg/L NO3.

CONCLUSIONS

The growing health concerns associated with nitrate contamination suggest that increased reporting of water quality is required. Implications for public health: Mandatory reporting of water quality laboratory reports by bottled water producers would improve transparency to consumers and help public health researchers track potential threats to water quality as new evidence emerges.

Exposure to widespread drinking water chemicals, blood inflammation markers, and colorectal cancer

BACKGROUND

Trihalomethanes (THMs) and nitrate are widespread chemicals in drinking water associated with colorectal cancer risk but mechanisms are not well understood.

OBJECTIVES

We explored the association between exposure to THMs and nitrate in drinking water and inflammation markers, and the link with colorectal cancer risk.

METHODS

A subset of 198 colorectal cancer cases and 205 controls from the multicase-control study MCC-Spain were included. Average concentration of THMs (chloroform, bromodichloromethane, dibromochloromethane, bromoform) and nitrate in tap water at the residence was estimated from age 18 until 2 years before the interview ("long term") and for a recent period (3 years before diagnosis). Serum levels of EGF, eotaxin, G-CSF, IL-17E, IL-1rA, IL-8, IP-10, MDC, MPO, periostin, VEGF, and C-reactive protein (CRP) were measured. We estimated the linear association between inflammation markers and exposure among controls, and the odds ratio of colorectal cancer associated with THM and nitrate exposure, and inflammation markers. A mediation analysis was conducted to identify inflammation markers in the pathway between THM/nitrate exposure and colorectal cancer.

RESULTS

Serum concentrations of EGF, IL-8, IL-17E and eotaxin increased with recent residential levels of brominated THMs, chloroforom and/or total THM. No associations were observed for nitrate and for long-term residential THM levels. All residential exposures except chloroform were positively associated with colorectal cancer. Serum concentrations of VEGF and periostin were positively associated with colorectal cancer, while EGF was inversely associated. One protein-exposure combination (periostin-recent ingested brominated THMs) slightly mediated the association with colorectal cancer risk.

DISCUSSION

Results suggest that estimated THM exposure is involved in inflammation processes. However, the study design was limited to stablish etiologically relevant associations between the protein levels and colorectal cancer risk. The lack of association between nitrate exposure and inflammation markers suggests other biological mechanisms are involved in the link with colorectal cancer.

Exposure to drinking water trihalomethanes and nitrate and the risk of brain tumours in young people

Brain tumours (BTs) are one of the most frequent tumour types in young people. We explored the association between tap water, exposure to trihalomethanes (THM) and nitrate and neuroepithelial BT risk in young people. Analysis of tap water consumption were based on 321 cases and 919 appendicitis controls (10-24 years old) from 6 of the 14 participating countries in the international MOBI-Kids case-control study (2010-2016). Available historical residential tap water concentrations of THMs and nitrate, available from 3 countries for 86 cases and 352 controls and 85 cases and 343 for nitrate, respectively, were modelled and combined with the study subjects' personal consumption patterns to estimate ingestion and residential exposure levels in the study population (both pre- and postnatal). The mean age of participants was 16.6 years old and 56% were male. The highest levels and widest ranges for THMs were found in Spain (residential and ingested) and Italy and in Korea for nitrate. There was no association between BT and the amount of tap water consumed and the showering/bathing frequency. Odds Ratios (ORs) for BT in relation to both pre- and postnatal residential and ingestion levels of THMs were systematically below 1 (OR = 0.37 (0.08-1.73)) for postnatal average residential THMs higher than 66 μg/L. For nitrate, all ORs were above 1 (OR = 1.80 (0.91-3.55)) for postnatal average residential nitrate levels higher than 8.5 mg/L, with a suggestion of a trend of increased risk of neuroepithelial BTs with increasing residential nitrate levels in tap water, which appeared stronger in early in life. This, to our knowledge, is the first study on this topic in young people. Further research is required to clarify the observed associations.

Health risk assessment of nitrate and fluoride in bottled water: a case study of Iran

Bottled water use has become widespread in recent years. Many Iranian cities are located in regions with a hot and semi-hot climate, and the quality of drinking water is low in most of these areas. Nitrate and fluoride are chemical constituents of drinking water with significant health concerns since they can be harmful in concentrations higher than drinking water standards. This study aims to determine nitrate and fluoride concentrations in different bottled water brands in the study region; evaluate the non-carcinogenic health risks posed by nitrate and fluoride exposure via the ingestion of bottled water; and compare the measured nitrate and fluoride concentrations with the amounts reported on the bottle labels. Twenty bottled water brands were sampled, and their nitrate and fluoride amounts were determined using the spectrophotometry method. The results revealed that 100% of nitrate and 70% of fluoride in samples had concentrations greater than the levels reported on bottle labels. Minimum, maximum, and mean concentrations for nitrate were, respectively, 1.1, 28, and 8.37 mg/L, and for fluoride were 0.014, 2.36, and 0.63 mg/L. The hazard quotient (HQ) values due to nitrate intake were > 1 in 10% of the samples (n = 2) for both infants and children, indicating potential adverse non-carcinogenic health effects upon consumption. For fluoride intake, the potential adverse health effects (HQ > 1) for infants, children, teenagers, and adults were respectively high in 30, 20, 10, and 10% of the samples. For nitrate, the 95th centile for infants was 1.547, and for fluoride, it was 2.62, 2.19, 1.15, and 1 for infants, children, teenagers, and adults, respectively.

Chemical and in vitro bioanalytical assessment of drinking water quality in Manhiça, Mozambique

BACKGROUND

The chemical quality of drinking water is widely unknown in low-income countries.

OBJECTIVE

We conducted an exploratory study in Manhiça district (Mozambique) to evaluate drinking water quality using chemical analyses and cell-based assays.

METHODS

We measured nitrate, fluoride, metals, pesticides, disinfection by-products, and industrial organochlorinated chemicals, and conducted the bioassays Ames test for mutagenicity, micronuclei assay (MN-FACS), ER-CALUX, and antiAR-CALUX in 20 water samples from protected and unprotected sources.

RESULTS

Nitrate was present in all samples (median 7.5 mg/L). Manganese, cobalt, chromium, aluminium, and barium were present in 90-100% of the samples, with median values of 32, 0.6, 2.0, 61, 250 μg/l, respectively. Manganese was above 50 μg/l (EU guideline) in eight samples. Arsenic, lead, nickel, iron, and selenium median values were below the quantification limit. Antimony, cadmium, copper, mercury, zinc and silver were not present. Trihalomethanes, haloacetic acids, haloacetonitriles and haloketones were present in 5-28% samples at levels ≤4.6 μg/l. DDT, dieldrin, diuron, and pirimiphos-methyl were quantified in 2, 3, 3, and 1 sample, respectively (range 12-60 ng/L). Fluoride was present in one sample (0.11 mg/l). Trichloroethene and tetrachloroethene were not present. Samples were negative in the in vitro assays.

SIGNIFICANCE

Results suggest low exposure to chemicals, mutagenicity, genotoxicity and endocrine disruption through drinking water in Manhiça population. High concentration of manganese in some samples warrants confirmatory studies, given the potential link to impaired neurodevelopment.

Ecological risk assessment of hexavalent chromium and silicon dioxide in well water in Maros Regency, Indonesia

OBJECTIVE

This paper assesses the potential ecological risk of hexavalent chromium (Cr(VI)) and silicon dioxide/silica (SiO₂) in well water. Both of pollutants have been classified as carcinogenic compound. The ecological risk assessment of drinking water is an effective tool to evaluate drinking water quality to reduce further risk.

METHOD

Fourteen well water samples were collected around the residential area near cement industrial activity and karst mining area. Estimating the ecological risk of well water which consumed daily evaluated based on Hazard Quotient (HQ) ratio.

RESULTS

The mean values of Cr(VI) and SiO₂ in well water samples were 0.0017mg/L and 12.94mg/L, respectively. Drinking water in this area are unacceptable. HQ values for SiO₂ at all stations are more than 1 (moderate level).

CONCLUSIONS

Cr(VI) and SiO₂ are discoverable within well water surrounding the research location. This finding is used as scientific data and references for ecological protection of drinking water in Maros.

Inorganic arsenic exposure and neuropsychological development of children of 4-5 years of age living in Spain

Early-life exposure to inorganic arsenic (iAs) may adversely impact health later in life. To date, evidence of iAs adverse effects on children's neurodevelopment comes mainly from populations highly exposed to contaminated water with conflicting results. Little is known about those effects among populations with low iAs exposure from food intake. We investigated the cross-sectional association between exposure to iAs and neurodevelopment scores among children living in Spain whose main route of exposure was diet. Arsenic species concentrations in urine from 400 children was determined, and the sum of urinary iAs, dimethylarsinic acid, and monomethylarsonic acid was used to estimate iAs exposure. The McCarthy Scales of Children's Abilities was used to assess children's neuropsychological development at about 4-5 years of age. The median (interquartile range) of children's sum of urinary iAs, MMA, and DMA was 4.85 (2.74-7.54) μg/L, and in adjusted linear regression analyses the natural logarithm transformed concentrations showed an inverse association with children's motor functions (β, [95% confidence interval]; global scores (-2.29, [-3.95, -0.63])), gross scores (-1.92, [-3.52, -0.31]) and fine scores (-1.54, [-3.06, -0.03]). In stratified analyses by sex, negative associations were observed with the scores in the quantitative index (-2.59, [-5.36, 0.17]) and working memory function (-2.56, [-5.36, 0.24]) only in boys. Our study suggests that relatively low iAs exposure may impair children's neuropsychological development and that sex-related differences may be present in susceptibility to iAs related effects; however, our findings should be interpreted with caution given the possibility of residual confounding.

Drinking Water Nitrate and Human Health: An Updated Review

Nitrate levels in our water resources have increased in many areas of the world largely due to applications of inorganic fertilizer and animal manure in agricultural areas. The regulatory limit for nitrate in public drinking water supplies was set to protect against infant methemoglobinemia, but other health effects were not considered. Risk of specific cancers and birth defects may be increased when nitrate is ingested under conditions that increase formation of N-nitroso compounds. We previously reviewed epidemiologic studies before 2005 of nitrate intake from drinking water and cancer, adverse reproductive outcomes and other health effects. Since that review, more than 30 epidemiologic studies have evaluated drinking water nitrate and these outcomes. The most common endpoints studied were colorectal cancer, bladder, and breast cancer (three studies each), and thyroid disease (four studies). Considering all studies, the strongest evidence for a relationship between drinking water nitrate ingestion and adverse health outcomes (besides methemoglobinemia) is for colorectal cancer, thyroid disease, and neural tube defects. Many studies observed increased risk with ingestion of water nitrate levels that were below regulatory limits. Future studies of these and other health outcomes should include improved exposure assessment and accurate characterization of individual factors that affect endogenous nitrosation.

Does nitrite and nitrate levels in drinking water impact the health of people in Dakahlia governorate, Egypt?

A total of 1291 drinking water samples were examined for nitrite and nitrate during 6 months from December, 2015 to May, 2016 at 17 cities of Dakahlia governorate (Nile Delta, north of Egypt), and the results were utilized for assessment of health risk of the exposure from drinking water by calculating average daily intake (ADI), hazard quotient (HQ), and the hazard index (HI). The nitrite and nitrate in drinking water had a concentration range of 0.030-0.113 and 2.41-8.70 mg L^-1, with mean values of 0.059 ± 0.014 and 5.25 ± 1.61 mg L^-1, respectively. Nitrite and nitrate levels in rural areas and ground water samples were significantly higher than that in the urban ones. None of the analyzed samples exceeded WHO guideline values that set out to prevent methemoglobinemia. The values of HQ and HI for all age groups do not exceed unity indicating a low risk of methaemoglobinaemia for the population in this area. Results of the present study indicate that there is no health risk of residents from nitrite and nitrate through drinking water in the studied area. However, the other sources of exposure to nitrite and nitrate should be investigated in further studies.

Concentrations of urinary arsenic species in relation to rice and seafood consumption among children living in Spain

Inorganic arsenic (i-As) has been related to wide-ranging health effects in children, leading to lifelong concerns. Proportionally, dietary i-As exposure dominates in regions with low arsenic drinking water. This study aims to investigate the relation between rice and seafood consumption and urinary arsenic species during childhood and to assess the proportion of urinary i-As metabolites. Urinary arsenic species concentration in 400 4-year-old children living in four geographical areas of Spain, in addition to repeated measures from 100 children at 7 years of age are included in this study. Rice and seafood products intake was collected from children's parents using a validated food frequency questionnaire (FFQ). At 4 years of age, children's urine i-As and monomethylarsonic acid (MMA) concentrations increased with rice product consumption (p-value = 0.010 and 0.018, respectively), and urinary arsenobetaine (AsB) with seafood consumption (p = 0.002). Four-year-old children had a higher consumption of both rice and seafood per body weight and a higher urinary %MMA (p-value = 0.001) and lower % dimethylarsinic acid (DMA) (p-value = 0.017). This study suggests increased dietary i-As exposure related to rice product consumption among children living in Spain, and the younger ones may be especially vulnerable to the health impacts of this exposure also considering that they might have a lower i-As methylation capacity than older children. In contrast, seafood consumption did not appear to influence the presence of potentially toxic arsenic species in this population of children.

Chemical quality of tap water in Madrid: multicase control cancer study in Spain (MCC-Spain)

Chronic consumption of water, which contains contaminants, may give rise to adverse health effects. The Madrid region, covered by the population-based multicase-control (MCC-Spain) study, includes two drinking water supply areas. The different sources of the water, coupled together with the possible differences in water management, mean that there may be differences in drinking water quality. In the context of the MCC study, our aims were to describe contaminant concentrations in tap water drawn from various sampling points distributed around the region, assess these concentrations by reference to guideline values and study possible differences between the two supply areas. Tap water samples were collected from 34 sampling points in 7 towns in the Madrid region (19-29 April 2010), and 23 contaminants (metals, nitrates, disinfection by-product and Mutagen X levels) were quantified. We undertook a descriptive analysis of the contaminant concentrations in the water and compared them between the two water supply areas (Wilcoxon test). We created maps representing the distribution of the concentrations observed at water sampling points and assessed the correlations (Spearman's coefficient) between the different parameters measured. The concentrations of the contaminants were below guideline values. There were differences between the two supply areas in concentration of nitrates (p value = 0.0051) and certain disinfection by-products. While there were positive correlations (rho >0.70) among some disinfection by-products, no correlations were found in metals or nitrates. The differences in nitrate levels could be linked to differences in farming/industrial activities in the catchment areas and in disinfection by-products might be related to the existence of different treatment systems or bromine content in source waters.

Ingested Nitrate and Breast Cancer in the Spanish Multicase-Control Study on Cancer (MCC-Spain)

BACKGROUND

Ingested nitrate leads to endogenous formation of N-nitroso compounds that are breast carcinogens in animals, but human evidence is limited.

OBJECTIVE

We evaluated ingested nitrate as a risk factor for breast cancer (BC) in a multicase-control study.

METHODS

Hospital-based incident BC cases and population-based controls were recruited in eight Spanish regions in 2008-2013; participants provided residential and water consumption from 18 years of age and information on known BC risk factors. Long-term nitrate levels (1940-2010) were estimated and linked with residential histories and water consumption to calculate waterborne ingested nitrate (milligrams/day). Dietary ingested nitrate (milligrams/day) was calculated using food frequency questionnaires and published dietary nitrate contents. Interactions with endogenous nitrosation factors and other variables were evaluated. A total of 1,245 cases and 1,520 controls were included in the statistical analysis.

RESULTS

Among the study regions, average ± SD waterborne ingested nitrate ranged from 2.9 ± 1.9 to 13.5 ± 7.5 mg/day, and dietary ingested nitrate ranged from 88.5 ± 48.7 to 154 ± 87.8 mg/day. Waterborne ingested nitrate was not associated with BC overall, but among postmenopausal women, those with both high nitrate (> 6 vs. < 2.6 mg/day) and high red meat intake (≥ 20 vs. < 20 g/day) were more likely to be cases than women with low nitrate and low red meat intake (adjusted odds ratio = 1.64; 95% confidence interval: 1.08, 2.49; overall interaction p-value = 0.17). No association was found with dietary nitrate.

CONCLUSIONS

Waterborne ingested nitrate was associated with BC only among postmenopausal women with high red meat consumption. Dietary nitrate was not associated with BC regardless of the animal or vegetable source or of menopausal status.

CITATION

Espejo-Herrera N, Gracia-Lavedan E, Pollan M, Aragonés N, Boldo E, Perez-Gomez B, Altzibar JM, Amiano P, Zabala AJ, Ardanaz E, Guevara M, Molina AJ, Barrio JP, Gómez-Acebo I, Tardón A, Peiró R, Chirlaque MD, Palau M, Muñoz M, Font-Ribera L, Castaño-Vinyals G, Kogevinas M, Villanueva CM. 2016. Ingested nitrate and breast cancer in the Spanish Multicase-Control Study on Cancer (MCC-Spain). Environ Health Perspect 124:1042-1049; http://dx.doi.org/10.1289/ehp.1510334.

Colorectal cancer risk and nitrate exposure through drinking water and diet

Ingested nitrate leads to the endogenous synthesis of N-nitroso compounds (NOCs), animal carcinogens with limited human evidence. We aimed to evaluate the risk of colorectal cancer (CRC) associated with nitrate exposure in drinking water and diet. A case-control study in Spain and Italy during 2008-2013 was conducted. Hospital-based incident cases and population-based (Spain) or hospital-based (Italy) controls were interviewed on residential history, water consumption since age 18, and dietary information. Long-term waterborne ingested nitrate was derived from routine monitoring records, linked to subjects' residential histories and water consumption habits. Dietary nitrate intake was estimated from food frequency questionnaires and published food composition databases. Odd ratios (OR) were calculated using mixed models with area as random effect, adjusted for CRC risk factors and other covariables. Generalized additive models (GAMs) were used to analyze exposure-response relationships. Interaction with endogenous nitrosation factors and other covariables was also evaluated. In total 1,869 cases and 3,530 controls were analyzed. Average waterborne ingested nitrate ranged from 3.4 to 19.7 mg/day, among areas. OR (95% CIs) of CRC was 1.49 (1.24, 1.78) for >10 versus ≤5 mg/day, overall. Associations were larger among men versus women, and among subjects with high red meat intake. GAMs showed increasing exposure-response relationship among men. Animal-derived dietary nitrate was associated with rectal, but not with colon cancer risk. In conclusion, a positive association between CRC risk and waterborne ingested nitrate is suggested, mainly among subgroups with other risk factors. Heterogeneous effects of nitrate from different sources (water, animal and vegetables) warrant further research.

[Nitrate concentrations in tap water in Spain]

OBJECTIVE

To determine nitrate concentrations in drinking water in a sample of Spanish cities.

MATERIAL AND METHODS

We used ion chromatography to analyze the nitrate concentrations of public drinking water in 108 Spanish municipalities with more than 50,000 inhabitants (supplying 21,290,707 potential individuals). The samples were collected between January and April 2012. The total number of samples tested was 324.

RESULTS

The median nitrate concentration was 3.47 mg/L (range: 0.38-66.76; interquartile range: 4.51). The water from 94% of the municipalities contained less than 15 mg/L. The concentration was higher than 25mg/L in only 3 municipalities and was greater than 50mg/L in one.

CONCLUSIONS

Nitrate levels in most public drinking water supplies in municipalities inhabited by almost half of the Spanish population are below 15 mg/L.

Nitrate in drinking water and bladder cancer risk in Spain

BACKGROUND

Nitrate is a widespread contaminant in drinking water and ingested nitrate under conditions resulting in endogenous nitrosation is suspected to be carcinogenic. However, the suggested association between nitrate in drinking water and bladder cancer remains inconsistent. We evaluated the long-term exposure to drinking water nitrate as a risk factor for bladder cancer, considering endogenous nitrosation modifiers and other covariables.

METHODS

We conducted a hospital-based case-control study of bladder cancer in Spain (1998-2001). Residential histories and water consumption information were ascertained through personal interviews. Historical nitrate levels (1940-2000) were estimated in study municipalities based on monitoring records and water source. Residential histories of study subjects were linked with nitrate estimates by year and municipality to calculate individual exposure from age 18 to recruitment. We calculated odds ratios (OR) and 95% confidence intervals (CI) for bladder cancer among 531 cases and 556 controls with reliable interviews and nitrate exposure information covering at least 70% of years from age 18 to interview.

RESULTS

Average residential levels ranged from 2.1mg/L to 12.0mg/L among regions. Adjusted OR (95%CI) for average residential levels relative to ≤ 5 mg/L were 1.2 (0.7-2.0) for >5-10mg/L and 1.1 (0.6-1.9) for >10mg/L. The OR for subjects with longest exposure duration (>20 years) to highest levels (>9.5mg/L) was 1.4 (0.9-2.3). Stratification by intake of vitamin C, vitamin E, meat, and gastric ulcer diagnosis did not modify these results. A non-significant negative association was found with waterborne ingested nitrate with an OR of 0.7 (0.4-1.0) for >8 vs. ≤ 4 mg/day. Adjustment for several covariables showed similar results to crude analyses.

CONCLUSION

Bladder cancer risk was inconsistently associated with chronic exposure to drinking water nitrate at levels below the current regulatory limit. Elevated risk is suggested only among subjects with longest exposure duration to the highest levels. No evidence of interaction with endogenous nitrosation modifiers was observed.

Population-based multicase-control study in common tumors in Spain (MCC-Spain): rationale and study design

INTRODUCTION

We present the protocol of a large population-based case-control study of 5 common tumors in Spain (MCC-Spain) that evaluates environmental exposures and genetic factors.

METHODS

Between 2008-2013, 10,106 subjects aged 20-85 were enrolled in 23 hospitals and primary care centres in 12 Spanish provinces including 1,112 cases with a new diagnosis of prostate cancer, 1,738 of breast cancer, 2,140 of colorectal cancer, 459 of gastro-oesophageal cancer, 559 cases with chronic lymphocytic leukaemia and 4,098 population controls frequency matched to cases by age, sex and region of residence. Participation rates ranged from 57% (stomach cancer) to 87% (CLL cases) and from 30% to 77% in controls. Participants completed a face-to-face computerized interview on sociodemographic factors, environmental exposures, occupation, medication, lifestyle, and personal and family medical history. In addition, participants completed a self-administered food-frequency questionnaire and telephone interviews. Blood samples were collected from 76% of participants while saliva samples were collected in CLL cases and participants refusing blood extractions. Clinical information was recorded for cases and paraffin blocks and/or fresh tumor samples are available in most collaborating hospitals. Genotyping was done through an exome array enriched with genetic markers in specific pathways. Multiple analyses are planned to assess the association of environmental, personal and genetic risk factors for each tumor and to identify pleiotropic effects.

DISCUSSION

This study, conducted within the Spanish Consortium for Biomedical Research in Epidemiology & Public Health (CIBERESP), is a unique initiative to evaluate etiological factors for common cancers and will promote cancer research and prevention in Spain.

Pharmacology and therapeutic role of inorganic nitrite and nitrate in vasodilatation

Nitrite has emerged as an important bioactive molecule that can be biotransformed to nitric oxide (NO) related metabolites in normoxia and reduced to NO under hypoxic and acidic conditions to exert vasodilatory effects and confer a variety of other benefits to the cardiovascular system. Abundant research is currently underway to understand the mechanisms involved and define the role of nitrite in health and disease. In this review we discuss the impact of nitrite and dietary nitrate on vascular function and the potential therapeutic role of nitrite in acute heart failure.