Evaluation of carcinogenic risks related to nitrate exposure in drinking water in Iran

Hydrogeochemical characterization and geospatial assessment of groundwater quality in the alluvial aquifer of southwestern Punjab in association with health risk assessment due to nitrate and fluoride pollution

Groundwater contamination is a significant threat to human health and hygiene, particularly when high levels of nitrate and fluoride are present. Punjab is currently experiencing a crisis of groundwater depletion and contamination, particularly severe in the southwestern region due to the limited availability of surface water. So, the present study was planned in the Mansa district of Punjab to know the status of groundwater with special reference to nitrate and fluoride and its associated health risks. The study found that all drinking water parameters in the district exceeded the desirable limits. The order of cations found was Na+  > Mg2+  > Ca2+  > K+, and the anions were ordered as HCO3-  > SO42-  > Cl-  > NO3-  > F-. The variation in Na+, K+, Mg2+, and HCO3- levels is attributed to processes such as silicate weathering, evaporation, and direct ion exchange. The dominant types of groundwater in the area are mixed type and Na-Cl type. The concentration of NO3- varied from 13.3 to 56.9 mg L-1 with mean 33.3 mg L-1, while F- ranged from 0.09 to 1.81 mg L-1 with mean 1.07 mg L-1. The study revealed that 23.2% and 12.6% of water samples in the district exceeded the acceptable limits for nitrate and fluoride, respectively. According to the water quality index (WQI), the majority of groundwater in the study area is categorized as very poor (36.6%) for drinking, with the largest contribution from the Budhlada (43.9%) and Sardoolgarh (41.1%) blocks. The hazard quotient (HQ) for NO3- was below 1 for adults. However, HQ was greater than 1 for children in all blocks except for the Bhikhi. Similarly, for fluoride, HQ was less than 1 in all blocks for both children and adults, except for children in Sardoolgarh block. The cancer risk due to nitrate exceeded acceptable limits in all blocks. Conclusively, the study results indicate that the Mansa district of Punjab is facing severe groundwater contamination due to nitrate and fluoride, with the highest contamination levels in Jhunir (47.4% of samples exceeded the acceptable limit of NO3-) and Sardoolgarh (87.18% samples exceeded the desirable limit of F-) blocks of the district. The study recommends implementing strict policies to regulate the use of agrochemicals in fields to mitigate nitrate pollution in groundwater and reduce associated risks.

Monitoring of urinary nickel and chromium in metal industries workers in Alborz, Iran

Heavy metal contamination from occupational sources is a cause for concern due to its potential accumulation in the environment and the body of living organisms, which leads to long-term toxic effects. There is limited evidence on the concentration of heavy metals in the body fluids of welding workers. This study aimed to measure the concentration of nickel (Ni) and chromium (Cr) as two main toxic heavy metals in the urine samples of welders and determine the potential relationship of various environmental factors on their concentration levels. This study was conducted in Iran in 2022-2023. Eighty-five urine samples were collected from the studied welding workers. Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to measure the concentration of Ni and Cr. Data related to socio-demographic characteristics (education level, income, work experience, age, and body mass index (BMI)), lifestyle profile (consumption of seafood and canned food, smoking, physical activity), type of ventilation and preventive devices at work, and suffering from underlying diseases (cardiovascular and high blood pressure) were collected using valid questionnaires. Ni and Cr were present in 100% of urine samples with mean concentrations of (1.09 ± 0.294) and (11.45 ± 16.751) µg/g creatinine, respectively. A significant correlation was observed between the mean concentration of Ni and Cr with the level of education, income, work experience, age, consumption of seafood and canned food, smoking, type of ventilation and preventive devices, and underlying diseases (p-value < 0.05). Also, there was no significant difference between Ni concentration and physical activity and Cr concentration with BMI. Lifestyle determinants and not using preventive devices are important predictors of urinary heavy metals in welding workers. Therefore, more research is required to determine the adverse effects of long-term exposure to these heavy metals.

Land use & land cover dynamics and its relationship with nitrate pollution in groundwater around inactive mine areas using geospatial techniques, SW part of Cuddapah basin, Southern India

Geospatial maps can show how the ineffective operations of inactive mines affect water and aquifer quality. As such, the purpose of this study is to assess the impact of mining and irrigation on the aquifer ecosystem through the evaluation of LULC and slope maps through the application of Landsat 8 OLI/TIRS and DEM data. A total of 50 groundwater samples were prepared from villages in the close proximity to inactive mines during pre and post monsoon periods in 2021. The results of the analysis revealed alarming statistics, that 14% of groundwater samples exceeded the WHO nitrate limit in pre & post monsoon season, indicating a high-risk in the study area. According to guidelines (USEPA, 2014), 34% in pre-monsoon and 26% post-monsoon of samples exceeded the THI levels for adults and children respectively, indicating non-carcinogenic health risks. In addition, 80% of the samples in both seasons exhibited high NPI values, indicating nitrate contamination associated with blue baby syndrome. From the Geospatial analysis the findings from the LULC classification indicate that there has been a significant increase in cropland area from 2016 to 2021 due to changes in forest land, fallow land, and water resources. These problems have been exacerbated by the expansion of cultivated land, which has increased from 71.1 square kilometers in 2016 to 118 square kilometers in 2021, accounting for 13.1% of the total area. This expansion, coupled with elevated water body resource availability, has compounded the nitrate pollution including in intensely irrigated regions. The slope map analysis revealed that the inactive mines occur at low slope, high rainfall areas and these are compounded by runoff from other sources such as domestic and agricultural wastes. For these matters, sealing and remediating these inactive mines is essential so as to prevent further nitrate leakage.

Geographical distribution of nitrate pollution and its risk assessment using GIS and Monte Carlo simulation in drinking water in urban areas of Fars province-Iran during 2017-2021

Pollution of water resources with nitrate is currently one of the major challenges at the global level. In order to make macro-policy decisions in water safety plans, it is necessary to carry out nitrate risk assessment in underground water, which has not been done in Fars province for all urban areas. In the current study, 9494 drinking water samples were collected in four seasons in 32 urban areas of Fars province in Iran, between 2017 and 2021 to investigate the non-carcinogenic health risk assessment. Geographical distribution maps of hazard quotient were drawn using geographical information system software. The results showed that the maximum amount of nitrate in water samples in 4% of the samples in 2021, 2.5% of the samples in 2020 and 3% of the samples in 2019 were more than the standard declared by World Health Organization guidelines (50 mg/L). In these cases, the maximum amount of nitrate was reported between 82 and 123 mg/L. The HQ values for infants did not exceed 1 in any year, but for children (44% ± 10.8), teenagers (10.8% ± 8.4), and adults (3.2% ± 1.7) exceeded 1 in cities, years, and seasons, indicating that three age groups in the studied area are at noticeably significant non-carcinogenic risk. The results of the Monte Carlo simulation showed that the average value of non-carcinogenic risk was less than 1 for all age groups. Moreover, the maximum HQ values (95%) were higher than 1 for both children and teenager, indicating a significant non-carcinogenic risk for the two age groups.

Human health risk of nitrate in groundwater of Tehran-Karaj plain, Iran

Groundwater pollution by nitrate has is a major concern in the Tehran-Karaj aquifer, Iran, where the wells provide up to 80% of the water supply for a population of more than 18 million-yet detailed human health risks associated with nitrate are unknown due to the lack of accessible data to adequately cover the aquifer in both place and time. Here, using a rich dataset measured annually in more than 75 wells, we mapped the non-carcinogenic risk of nitrate in the aquifer between 2007 and 2018, a window with the most extensive anthropogenic activities in this region. Nitrate concentration varied from ~ 6 to ~ 150 mg/L, around three times greater than the standard level for drinking use, i.e. 50 mg/L. Samples with a non-carcinogenic risk of nitrate, which mainly located in the eastern parts of the study region, threatened children's health, the most vulnerable age group, in almost all of the years during the study period. Our findings revealed that the number of samples with a positive risk of nitrate for adults decreased in the aquifer from 2007 (17 wells) to 2018 (6 wells). Although we hypothesized that unsustainable agricultural practices, the growing population, and increased industrial activities could have increased the nitrate level in the Tehran-Karaj aquifer, improved sanitation infrastructures helped to prevent the intensification of nitrate pollution in the aquifer during the study period. Our compilation of annually mapped non-carcinogenic risks of nitrate is beneficial for local authorities to understand the high-risk zones in the aquifer and for the formulation of policy actions to protect the human health of people who use groundwater for drinking and other purposes in this densely populated region.

Assessing the carcinogenic and non-carcinogenic health risks of metals in the drinking water of Isfahan, Iran

Metals are significant contributors to water pollution, posing serious threats to human health. This study aims to assess the carcinogenic and non-carcinogenic health risks associated with metals in Isfahan drinking water. Eighty water samples were randomly collected from the city's distribution network between January and March 2020-2021. Inductively coupled plasma Optical Emission Spectrometry was used to measure toxic metals, namely Pb, Cr, Cd, Ni, and As concentrations. Results revealed that the mean concentration of Ni (70.03 µg/L) exceeded the WHO reference value (70 µg/L), while the other metals were below the standard values. The average chronic daily intake order of toxic metals was Ni > Cr > Pb > As > Cd. Non-carcinogenic risk assessment through hazard quotient (HQ) and hazard index (HI) demonstrated that both THI for adults (HQingestion + HQdermal = 4.02E-03) and THI for children (HIingestion + HIdermal = 3.83E-03) were below the acceptable limit (less than 1). This indicated no non-carcinogenic risk to residents through water ingestion or dermal exposure. However, findings indicated that the ingestion route was the primary exposure pathway, with HQ values for ingestion exceeding HQ values for dermal adsorption. Carcinogenic risk assessment showed that the risk associated with As metal exceeded the acceptable limit (1 × 10-6). Therefore, implementing treatment improvement programs and appropriate control measures is essential to safeguard the health of Isfahan City residents.

Nitrate removal from industrial wastewater using six newly isolated strains of aerobic heterotrophic denitrifiers in an attached growth

BACKGROUND

The objective of this study was to isolate specific heterotrophic aerobic denitrifying bacteria from a wastewater treatment plant and employ them in an attached growth system for wastewater denitrification.

METHODS

To isolate and screen aerobic denitrifiers, Denitrifying Medium (DM) and Screen Medium (GN) were utilized. The Polymerase Chain Reaction (PCR) technique and 16S rDNA sequencing were used to identify the isolates. The formation of biofilms by selected isolates on ceramic media was examined using a Scanning Electron Microscope (SEM). This study also investigated various variables for nitrate removal, including temperature, Carbon/Nitrogen ratio (C/N), and the carbon source. A series of experiments were conducted to gauge nitrate removal under optimal variable values.

RESULTS

Six purified strains exhibited the highest denitrification efficiency in less than 30 h. Pseudomonas species were chosen for additional experiments. Denitrification efficiencies ranged from a low of 71.4% (at a temperature of 30 °C, C/N ratio of 17, and citrate as the carbon source) to a high of 98.9% (at a temperature of 33 °C, C/N ratio of 8, and citrate as the carbon source). The average denitrification efficiency was 84.02%. Optimal nitrate removal occurred at temperatures around 30-31 °C and C/N ratios of approximately 5.8-6.5.

CONCLUSION

This study demonstrates that aerobic denitrifying bacteria can effectively remove nitrate from aqueous solutions.

Human health risk assessment of nitrate in private well waters of shallow quaternary alluvial aquifer

Excessive nitrate intake via ingestion pathway and dermal absorption exposures has adverse health impacts on human health. This study evaluated groundwater (GW) nitrate concentrations and health risks which focused on ingestion and dermal exposures to residents in Bachok District, Kelantan, Malaysia. Three hundred (300) samples of private wells were collected and it is found that the nitrate concentrations ranging between 0.11 and 64.01 mg/L NO3-N with a mean value of 10.45 ± 12.67 mg/L NO3-N. The possible health hazards of nitrate by ingestion and dermal contact were assessed using USEPA human health risk assessment model for adult males and females. It is observed that the mean Hazard Quotient (HQ) values of adult males and females were 0.305 ± 0.364 and 0.261 ± 0.330, respectively. About 7.3% (n = 10) and 4.9% (n = 8) of adult males and females had HQ values more than 1, respectively. It was also observed that the mean of HQderm was lesser than HQoral for males and females. The spatial distribution of HQ by interpolation method showed high nitrate concentrations (> 10 mg/L NO3-N) were distributed from the centre to the southern part of the study location, which identified as an agricultural area, indicating the used of nitrogenous fertilizers as the main source of GW nitrate contamination in this area. The findings of this study are valuable for establishing private well water protection measures to stop further deterioration of GW quality caused by nitrate.

Association between type of drinking water and upper gastrointestinal cancer incidence in the Linxian General Population

BACKGROUND

This study aimed to explore the association between drinking water source and risk of upper gastrointestinal (UGI) cancer, including esophageal cancer (EC) and gastric cancer (GC), in the Linxian General Population Nutrition Intervention Trial (NIT) cohort.

METHODS

In this study, we used data from the Linxian NIT cohort, which included 29,584 healthy adults aged 40 to 69 years. Subjects were enrolled in April 1986 and followed up until March 2016. Tap water drinking status and demographic characteristics were collected at baseline. Subjects who drank tap water were treated as the exposed group. Hazard ratios (HRs) and 95% confidence intervals (95% CIs) were estimated using the Cox proportional hazard model.

RESULTS

A total of 5,463 cases of UGI cancer were identified during the 30-year follow-up period. After adjusting for multiple factors, the incidence rate of UGI cancer in participants who drank tap water was significantly lower compared with individuals in the control (HR = 0.91, 95% CI: 0.86-0.97). A similar association was observed between tap water drinking and EC incidence (HR = 0.89, 95% CI: 0.82-0.97). The association between drinking tap water and risk of UGI cancer and EC incidence did not vary across the subgroup by age and gender (All Pinteraction > 0.05). For EC incidence, an interaction effect was observed for riboflavin/niacin supplements and drinking water source (Pinteraction = 0.03). No association was observed between drinking water source and GC incidence.

CONCLUSIONS

In this prospective cohort study in Linxian, participants who drank tap water had a lower risk of EC incidence. As a source of drinking water, use of tap water may reduce the risk of EC by avoiding exposure to nitrate/nitrite. Measures should be taken to improve the quality of drinking water in high-incidence areas of EC.

TRIAL REGISTRATION

The trial is registered with ClinicalTrials.gov (NCT00342654, 21/06/2006), and the trial name is Nutrition Intervention Trials in Linxian Follow-up Study.

Relationship between serum nitric oxide of patients with thyroid disorders and metabolic syndrome indices and nitrate concentration of water

This case-control study aimed to assess the effect of drinking water nitrate on serum nitric oxide concentration and the risk of metabolic syndrome (MetS) in the population in the Middle East. The study included 50 control and 50 thyroid disorder cases who were referred to two medical centers in 2021. In this study, serum nitric oxide concentration, drinking water nitrate, and metabolic syndrome components were measured in the two groups. The results showed there was a statistically significant difference between serum NO in the case and control groups (p-value < 0.001). There was a positive correlation between the concentration of nitrate in drinking water and serum nitric oxide in the case and control groups; however, this relationship was not significant statistically. A statistically significant difference was found between serum nitric oxide and systolic blood pressure in the cases (p-value < 0.05), but there was no significant difference between MetS and nitric oxide. Therefore, we concluded that the relationship between nitric oxide and nitrate in consuming water should be determined in thyroid patients. In addition to their water consumption, it is better to study the nitrate of foods, especially vegetables.

Groundwater characterization and non-carcinogenic and carcinogenic health risk assessment of nitrate exposure in the Mahanadi River Basin of India

Agriculture is the mainstay of India's economy and chemical fertilizers have been extensively used to meet increasing demands. Anthropogenic interventions at the soil surface, especially the application of nitrogenous fertilizers in agricultural fields, provide essential nutrients but become major pollutant sources in terrestrial ecosystems and aquatic environments. Groundwater samples from phreatic aquifers of the Mahanadi River Basin, Chhattisgarh, India, showed that the Ca²⁺-Mg²⁺-HCO₃^- freshwater type dominates, followed by the Ca²⁺-Mg²⁺-Cl- and Na⁺-HCO₃^- types. Increasing trends in the ionic ratios of (NO₃-+Cl-)/HCO₃- over TDS and of NO₃-/Cl- over Cl- indicated the significant impact of anthropogenic pollution on groundwater contamination. Deterministic and probabilistic approaches were used to assess the non-carcinogenic and carcinogenic health risks of nitrate to children and adults. Both approaches produced the same results and indicated children were more prone to non-carcinogenic health risk than adults. An excess gastric cancer risk (ER) exposure model showed that approximately 42% of the groundwater samples had a non-negligible ER (1.00 × 10^-4 to 1.00 × 10^-5). Sensitivity analysis indicated groundwater nitrate concentration, ingestion rate, and the percentage of nitrite from nitrate were the most significant variables in determining HI and ER. It is suggested to adopt proper management of control policies for reducing the elevated groundwater nitrate concentration in the present study area.

Comprehensive assessment of water quality and associated health risks in an arid region in south Iran

This study aims at investigating the quality of drinking water and evaluating the non-carcinogenic risk of fluoride and nitrate ions in drinking water, and fluoride in tea in Zarrin Dasht, Iran. We focus on tea since it is the most popular drink among Iranian people and in the study region. We collected and analyzed 23 drinking water samples and 23 tea samples from different locations in the study region. Based on the water quality index, the consumed drinking water does not have a good quality in most Zarrin Dasht areas. Accordingly, the water quality index (WQI) is poor and very poor in 70% and 13% of the water samples, respectively. The average fluoride concentration of the tea samples is 2.71 mg/L. The mean values of Fluoride Hazard Index (HI_fluoride) are 3.77, 2.77, and 2.33 for children, teenagers, and adults, respectively, which are higher than the safe limit of 1. The Nitrate Hazard Index (HI_nitrate) is higher than the safe limit of 1 in 8.7% of the samples. The results of the Monte Carlo simulation demonstrate that HI_fluoride and HI_nitrate are higher than 1 in all the groups, except for adults. According to the results of the sensitivity analysis, ingestion rate and body weight have a large effect on HI_fluoride and HI_nitrate, but body weight is inversely associated with sensitivity. According to the Piper diagram, saline water is the predominant type in Zarrin Dasht. Besides, the results of the principal component analysis (PCA) show a high correlation between fluoride and pH, which could be related to the effect of pH on fluoride dissolution and ion exchange. Therefore, appropriate measures are recommended to be taken in order to reduce the amount of fluoride in the drinking water resources of this region. Reduction of tea consumption can also be considered an important factor in decreasing the amount of fluoride intake.

Association between nitrate concentration in drinking water and rate of colorectal cancer: a case study in northwestern Iran

Nitrate, as a major pollutant of drinking water, is associated with colorectal cancer (CRC) and serves as an environmental health concern, especially in the districts with unregulated agriculture. In this case study in northwestern Iran, we used two databases of nitrate concentration (1999-2013) and age-standardized incidence rate (ASR) for CRC (2002-2012) from 19 counties of East Azerbaijan province. The trend and correlation between nitrate and ASR was investigated. Inverse distance weighted technique was used to spatially interpolate the maps. Expectedly, drinking water nitrate has increased throughout the province (8-20.5 mg/L) as well as the ASR for CRC of men (from 2.07 to 18.05 mg/L) and women (from 1.57 to 10.94 mg/L). While ASR for CRC of men was positively correlated to nitrate (Pearson's r = 0.624, p-value = 0.040), no statistically significant correlation was found between nitrate and ASR for women's CRC (Pearson's r = 0.289, p-value = 0.351). According to our findings, the incidence of CRC was not higher for those residing in the regions with higher nitrate, suggesting that risk factors such as genetic predisposition and diet that were not taken into account could be determinants of this pattern. However, even a small increase in CRC rate due to water nitrate could translate into a large public health concern. The incremental pattern observed in nitrate levels of different counties over the years gives the health policymakers a better perspective of the problem and how the control of water nitrate level as a CRC risk factor might contribute to the prevention of CRC.

Vulnerability to Nitrate Occurrence in the Spring Waters of the Sila Massif (Calabria, Southern Italy)

Knowledge of spring waters’ chemical composition is paramount for both their use and their conservation. Vast surveys at the basin scale are required to define the nature and the location of the springs and to identify the hydrochemical facies of their aquifers. The present study aims to evaluate the hydrochemical facies and the vulnerability to nitrates of 59 springs falling in the Sila Massif in Calabria (southern Italy) and to identify their vulnerability through the analysis of physicochemical parameters and the use of the Langelier–Ludwig diagram. A spatial analysis was performed by the spline method. The results identified a mean value of 4.39 mg NO₃⁻/L and a maximum value of 24 mg NO₃⁻/L for nitrate pollution in the study area. Statistical analysis results showed that the increase in electrical conductivity follows the increase in alkalinity values, a correlation especially evident in the bicarbonate Ca-Mg waters and linked to the possibility of higher nitrate concentrations in springs. These analyses also showed that nitrate vulnerability is dependent on the geological setting of springs. Indeed, the Sila igneous–metamorphic batholith, often strongly affected by weathering processes, contributes to not buffering the nitrate impacts on aquifers. Conversely, anthropogenic activities, particularly fertilization practices, are key factors in groundwater vulnerability.

An integrative water quality evaluation in two surface water bodies from a tropical agricultural region in Cartago, Costa Rica

A monitoring study was carried out in two micro-catchments in the Reventazón basin, in Northern Cartago, Costa Rica; pesticide occurrence and water quality were analyzed. Twelve pesticides were detected, five insecticides (chlorpyrifos, carbofuran, cypermethrin, imidacloprid, and oxamyl), four fungicides (carbendazim, imazalil, metalaxyl, and thiabendazole), and three herbicides (diuron, linuron, and terbutryn); eight of them presented risk quotients RQ >1, which implies a high risk for the environment. The water quality evaluation included fourteen physicochemical and microbiological parameters, out of which thermotolerant coliforms, nitrate, and total phosphorus exceeded a selected threshold value in every sample. Five metals were also included in the evaluation, Pb was the most frequent, followed by few detections of Cd, Cu, and Cr. Four water quality indexes (WQIs) were applied, two of them, the CCME WQI, based on physicochemical parameters, and the BMWP-CR WQI, based on benthic macroinvertebrate recount adapted to Costa Rican species, categorized all the sampling points as "bad" and "very bad" quality. This work of monitoring is important in the Latin American region, where there is a lack of information for regulation improvement and management decisions. These results showed poor management of the micro-catchments in this agricultural rural area.

Distributions, origins, and health-risk assessment of nitrate in groundwater in typical alluvial-pluvial fans, North China Plain

High concentration of nitrate (NO3-) in groundwater is a major concern because of its complex origin and harmful effects on human health. This study aims to investigate the distributions of nitrate in various aquifers and in areas with different land use types in alluvial-pluvial fans in North China Plain, to identify dominant sources and factors using hydrochemical data and principal component analysis, and to conduct health-risk assessment of groundwater nitrate using the models recommended by USEPA. Results show that approximately 76.1% groundwater in fissured aquifers showed high-NO3- (> 50 mg/L), and was 2.7 times of that in granular aquifers. In fissured aquifers, the proportion of high-NO3- groundwater (PHNG-WHO) in peri-urban areas was more than 1.3 times of those in other areas. Similarly, in shallow granular aquifers, the PHNG-WHO in peri-urban areas was also higher than that in other areas. By contrast, in deep granular aquifers, the PHNG-WHO in urbanized areas was 2.8 and 5.2 times of that in peri-urban areas and farmland, respectively. High NO3- levels in both granular and fissured aquifers originated mainly from domestic sewage and animal waste, and fertilizers are also important sources of NO3- in fissured aquifers. Intensive groundwater exploitation aggravated nitrate contamination because more thickness of vadose zones resulting from over-exploitation is in favor of nitrification. Risk assessment of groundwater nitrate indicated about 43.3%, 45.6%, and 54.2% of the groundwater samples showed unacceptable non-carcinogenic risk to adult males, adult females, and children, respectively. The proportion of samples with health risks had a significant positive correlation with the urbanization level. Our study indicates that several effective measures for pollution prevention, such as strengthening sewage treatment and prohibiting groundwater over-exploitation, must be adopted so as to ensure the sustainable management of groundwater and the safety of drinking water.

Nitrate in Groundwater Resources of Hormozgan Province, Southern Iran: Concentration Estimation, Distribution and Probabilistic Health Risk Assessment Using Monte Carlo Simulation

High nitrate concentration in drinking water has the potential to cause a series of harmful effects on human health. This study aims to evaluate the health risk of nitrate in groundwater resources of Hormozgan province in four age groups, including infants, children, teenagers, and adults, based on the US EPA methodology and Monte Carlo technique to assess uncertainty and sensitivity analysis. A Geographic Information System (GIS) was used to investigate the spatial distribution of nitrate levels in the study area. The nitrate concentration ranged from 0.3 to 30 mg/L, with an average of 7.37 ± 5.61 mg/L. There was no significant difference between the average concentration of nitrate in all study areas (p > 0.05). The hazard quotient (HQ) was less than 1 for all age groups and counties, indicating a low-risk level. The HQ95 for infants and children in the Monte Carlo simulation was 1.34 and 1.22, respectively. The sensitivity analysis findings showed that the parameter with the most significant influence on the risk of toxicity in all age groups was the nitrate content. Therefore, implementing a water resources management program in the study area can reduce nitrate concentration and enhance water quality.

Monitoring of urinary arsenic (As) and lead (Pb) among a sample of pregnant Iranian women

PURPOSE

Heavy metals, as significant toxic environmental contaminants, can cause serious adverse health outcomes on the human body even in trace concentrations. There is limited evidence on heavy metal concentrations existing in the body fluids of pregnant women. This study aims to evaluate the urinary levels of arsenic (As) and lead (Pb), as two main toxic heavy metals, among pregnant women and their lifestyle determinants.

METHODS

The study was performed in 2019-2020 in Isfahan, Iran. A number of 140 urine samples of pregnant women who were in their first pregnancy trimester were examined. Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to analyze the urinary concentrations of As and Pb. Socio-demographic data including age, pre-pregnancy body mass index (BMI), education status, and family income, as well as the use of cleaning products (cosmetic and household cleaning products), and lifestyle habits (food intake, smoking, and physical activity) were collected using a validated questionnaire.

RESULTS

The mean concentration of As and Pb were 8.14 ± 10.8 and 9.6 ± 7.1 μg/g creatinine, respectively. The mean urinary concentration of Pb indicated significant differences in the levels of cosmetic usage, second-hand smoking exposure, and the use of Copper, Aluminum, Teflon, Steel, and Enameled utensils for cooking (p-value < 0.05). Furthermore, the mean of urinary Pb concentrations at high levels of physical activity and scratched utensils using was significantly different from the other categories (p-value = 0.02). No significant differences were found between As and Pb concentration with other socio-demographic factors.

CONCLUSION

The lifestyle determinants and cosmetic products use are important predictors of urinary heavy metals in pregnant women, rather than sociodemographic characteristics. Additional research is necessary to determine long-term adverse birth outcomes of exposure to these heavy metals.

Prenatal exposure to chromium (Cr) and nickel (Ni) in a sample of Iranian pregnant women: urinary levels and associated socio-demographic and lifestyle factors

Heavy metals have been well documented to pose detrimental health effects. The current study aimed to measure the concentration of chromium (Cr) and nickel (Ni) in urinary samples of Iranian pregnant females and determine their potential correlations with different lifestyle variables. The study was conducted in 2019-2020 in Isfahan, Iran, and the urine samples were collected from 140 pregnant women. The concentrations of Cr and Ni in the urinary samples were measured by inductively coupled plasma optical emission spectrometry (ICP-OES). Data on socio-demographic characteristics, use of cleaning products, and lifestyle profiles was collected by validated questionnaires. Cr and Ni were detected in 100% of urinary samples with the mean concentration of 4.1±3.4 and 7.5±4.8 μg/g creatinine, respectively. Significant associations were found between the mean concentration of Cr and Ni with using cooking utensils made of copper, aluminum, Teflon, steel, and enameled, as well as with cosmetic use, and second-hand smoking exposure during pregnancy. The results also showed that the mean urinary Ni and Cr concentrations were significantly different among individuals who consumed seafood and canned food (p-value <0.05). Furthermore, the mean of urinary Cr and Ni concentrations at high levels of physical activity and scratched utensils used was significantly different from the other categories (p-value <0.05). According to our findings, the lifestyle determinants and cosmetic products had superiority to socio-demographic characteristics in predicting urinary heavy metals in Iranian pregnant women.

Assessment of the health risk and geo-accumulation of toxic metals in agricultural soil and wheat, northern Iran

The current work was conducted to study the concentrations of heavy metals (HMs) in farming soil and wheat and compute their geological and health indexes, including geo-accumulation index (I_geo), chronic daily intake (CDI), hazard index (HI), hazard quotient (HQ), and cancer risk (CR). In general, 256 samples were collected from agriculture soil (AS) and wheat in Kalaleh and Aq Qala areas, northern Iran. The average rates of Cd, Cu, Pb, and Zn were detected to be 0.28, 25.24, 15.44, and 60.33 mg·kg^-1, respectively, for AS and 0.01, 8.85, 0.73, and 33.81 mg·kg^-1 for wheat, respectively. Based on the results, the HQ and HI levels for investigated HMs were lower than l. So, the health risk of HMs exposure for adults and children was low. CR levels for Pb in AS for both children and adults were observed greater than the threshold value. Accordingly, lead-contaminated soil will be carcinogenic if ingested by children. On the other hand, the exposure to Pb (through wheat) and Cd (through both soil and wheat) had the acceptable CR level for all groups. As a result, for an extended period, there are no significant health consequences for children and adults.

Association between prenatal phthalate exposure and anthropometric measures of newborns in a sample of Iranian population

Phthalates or phthalic acid esters (PAEs) are a group of compounds which they can be entered into the human body through the various pathways. The aim of this study was to examine associations between prenatal phthalates exposure with anthropometric measures of neonates. Urine samples were obtained from 121 Iranian pregnant women at their first trimester of pregnancy, and the levels of monobutyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), and mono (2-ethyl-5hydroxyhexyl) phthalate (MEHHP) metabolites were determined by gas chromatography mass spectrometry (GC/MS). The correlations between the maternal urinary concentrations of phthalate metabolites with anthropometric measures of neonates as well as with the socio-demographic factors of participants (maternal education, age, family income, pre-pregnancy body mass index), their lifestyle variables (smoking habit, food pattern, and physical activity), and use of cleaning products (cosmetic and household cleaning products) were investigated. MBzP, MBP, MEHP, and MEHHP were detected in 100% of the participants with the concentration ranged 120 to 860 μg/g creatinine. Significant correlations were observed between the urinary levels of maternal MBzP (adjusted β = 0.3 (0.001), p = 0.03) and MEHHP (adjusted β = 0.3 (0.001), p = 0.04) with the birth weight of female neonates. MBP (adjusted β = -0.3 (0.02), p = 0.04) and MBzP (adjusted β = -0.3 (0.001), p = 0.02) had negative associations with the head circumference in male and female newborns, respectively. Furthermore, plastic packaging for pickle and passive smoking during pregnancy were identified to be significantly associated with low birth weight (p value < 0.05). Iranian pregnant women had higher concentrations of urinary phthalates compared to the other countries. Based on the findings, the higher prenatal exposure to phthalates could adversely impact the health status of newborns.

Degradation of 2, 4, 6-trinitrotoluene (TNT) from aqueous solution by coupled electrocoagulation process with persulfate salt

PURPOSE

The 2, 4, 6-trinitrotoluene (TNT) is the major explosive extensively applied in demolition of structure, military activity, and mining industry. This research was investigating the degradation rate of TNT in aqueous solution using electrochemical combined with persulfate anions.

METHODS

In this study, the effect of seven independent variables including pH, reaction time, current density, type (NaCl, Na₂SO₄, NaNO₃) and concentration of salts, initial concentration of TNT, scavenger type, and persulfate concentration were studied on TNT removal. High performance liquid chromatography (HPLC) was applied to measure TNT concentration.

RESULTS

The findings indicated that the optimum conditions for TNT reduction were pH = 5, time = 45 min, current density = 1.75 mA/cm², initial concentration of TNT = 25 mg/l, persulfate concentration = 0.3 mg/l, and Na₂SO₄ concentration = 1.75 mg/l which the removal rate of TNT was found to be 88.0 ± 4.4%.

CONCLUSION

According to the findings, electrocoagulation procedure is suggested as an applicable method in TNT reduction from aqueous solution.

Monitoring of urinary phthalate metabolites among pregnant women in Isfahan, Iran: the PERSIAN birth cohort

Recently, increasing evidences have shown that the exposure to phthalates can adversely affect health status of pregnant women and their newborns. However, only a limited number of studies have investigated the concentrations of these compounds in the body fluids of pregnant women. In the present study, we aimed to evaluate the concentrations of phthalate metabolites in urinary samples of pregnant women in correlation with the population characteristics and different lifestyle factors. The study was conducted in 2018-2019 and urinary samples were taken from 121 pregnant women during their first pregnancy trimester who lived in Isfahan, Iran. The concentrations of monobutyl phthalate (MBP), mono-benzyl phthalate (MBzP), mono-2-ethylhexyl phthalate (MEHP), and mono (2-ethyl-5hydroxyhexyl) phthalate (MEHHP) metabolites in urinary samples were determined by gas chromatography mass spectrometry (GC/MS). The socio-demographic profile of the participants (maternal education, age, family income, pre-pregnancy BMI), their lifestyle information (smoking habit, food pattern, and physical activity), cleaning products use data (cosmetic and household cleaning products) were collected by the use of PERSIAN birth cohort questionnaire. MBzP, MBP, MEHP, and MEHHP were detected in 100% of participated pregnant women with the mean concentration of 342.5 ± 193.8, 308.5 ± 229.4, 126.5 ± 118.3, and 866.5 ± 307.6 μg/g creatinine, respectively. Significant correlations were observed between the mean concentration of urinary phthalate metabolites with the following variables: using plastic packaging (for bread, lemon juice, pickle, leftover, and water), lower physical activity, passive smoking exposure during pregnancy (p value<0.05). Furthermore, the pre-pregnancy BMI (r = 0.27, r = 0.3, r = 0.26, and r = 0.26), use of the household cleaning products (r = 0.2, r = 0.22, r = 0.3, and r = 0.26), utilize of the cosmetic products (r = 0.46, r = 0.48, r = 0.49, and r = 0.54), and passive smoking status (r = 0.5, r = 0.44, r = 0.44, and r = 0.26) directly correlated with the urinary concentrations of MBP, MBzP, MEHP, and MEHHP, respectively. No significant association was seen between the concentration of urinary phthalate metabolites with the maternal education level and family income. According to our findings, higher amounts of phthalate metabolites were detected in urinary samples of pregnant women who were passive smokers, or had higher pre-pregnancy BMI and lower physical activity, as well as those women who used higher amounts of cosmetic and household cleaning products, or used plastic packaging for food and non-food products.