International Journal of Environmental Research and Public Health

Heavy metal (HM) contamination and accumulation is a serious problem around the world due to the toxicity, abundant sources, non-biodegradable properties, and accumulative behaviour of HMs. The degree of soil HM contamination in China, especially in the Yangtze River Delta, is prominent. In this study, 1822 pairs of soil and crop samples at corresponding locations were collected from the southern Yangtze River Delta of China, and the contents of Ni, Cr, Zn, Cd, As, Cu, Hg, and Pb were measured. The single pollution index in soil (SPI) and Nemerow composite pollution index (NCPI) were used to assess the degree of HM pollution in soil, and the crop pollution index (CPI) was used to explore the degree of HM accumulation in crops. The bioaccumulation factor (BAF) was used to investigate the translocation of heavy metals in the soil-crop system. The health risks caused by HMs were calculated based on the model released by the U.S. Environmental Protection Agency. The SPIs of all elements were at the unpolluted level. The mean NCPI was at the alert level. The mean CPIs were in the following decreasing order: Ni (1.007) > Cr (0.483) > Zn (0.335) > Cd (0.314) > As (0.232) > Cu (0.187) > Hg (0.118) > Pb (0.105). Only the mean content of Ni in the crops exceeded the national standard value. The standard exceeding rates were used to represent the percentage of samples whose heavy metal content is higher than the corresponding national standard values. The standard exceeding rates of Cu, Hg, and Cd in soil were significantly higher than corresponding values in crops. Meanwhile, the standard exceeding rates of Ni, As, and Cr in crops were significantly higher than corresponding values in soil. The chronic daily intake (CDI) of children (13.8 × 10−3) was the largest among three age groups, followed by adults (6.998 × 10−4) and seniors (5.488 × 10−4). The bioaccumulation factors (BAFs) of all crops followed the order Cd (0.249) > Zn (0.133) > As (0.076) > Cu (0.064) > Ni (0.018) > Hg (0.011) > Cr (0.010) > Pb (0.001). Therefore, Cd was most easily absorbed by crops, and different crops had different capacities to absorb HMs. The hazard quotient (HQ) represents the potential non-carcinogenic risk for an individual HM and it is an estimation of daily exposure to the human population that is not likely to represent an appreciable risk of deleterious effects during a lifetime. All the HQs of the HMs for the different age groups were significantly less than the alert value of 1.0 and were at a safe level. This indicated that citizens in the study area face low potential non-carcinogenic risk caused by HMs. The total carcinogens risks (TCRs) for children, adults, and seniors were 5.24 × 10−5, 2.65 × 10−5, and 2.08 × 10−5, respectively, all of which were less than the guideline value but at the alert level. Ingestion was the main pathway of carcinogen risk to human health.

Obesity is reaching epidemic proportions and is a strong risk factor for a number of cardiovascular and metabolic disorders such as hypertension, type 2 diabetes, dyslipidemia, atherosclerosis, and also certain types of cancers. Despite the constant recommendations of health care organizations regarding the importance of weight control, this goal often fails. Genetic predisposition in combination with inactive lifestyles and high caloric intake leads to excessive weight gain. Even though there may be agreement about the concept that lifestyle changes affecting dietary habits and physical activity are essential to promote weight loss and weight control, the ideal amount and type of exercise and also the ideal diet are still under debate. For many years, nutritional intervention studies have been focused on reducing dietary fat with little positive results over the long-term. One of the most studied strategies in the recent years for weight loss is the ketogenic diet. Many studies have shown that this kind of nutritional approach has a solid physiological and biochemical basis and is able to induce effective weight loss along with improvement in several cardiovascular risk parameters. This review discusses the physiological basis of ketogenic diets and the rationale for their use in obesity, discussing the strengths and the weaknesses of these diets together with cautions that should be used in obese patients.

Many times in the history of lead toxicology the view that “the problem” has been solved and is no longer a major health concern has prevailed, only to have further research demonstrate the prematurity of this judgment. In the last decade, an extraordinary amount of new research on lead has illustrated, all too clearly, that “the problem” has not disappeared, and that, in fact, it has dimensions never before considered. Recent risk assessments have concluded that research has yet to identify a threshold level below which lead can be considered “safe.” Although children’s intelligence has traditionally been considered to be the most sensitive endpoint, and used as the basis for risk assessment and standard setting, increased lead exposure has been associated with a wide variety of other morbidities both in children and adults, in some cases at biomarker levels comparable to those associated with IQ deficits in children. In adults, these endpoints include all-cause mortality and dysfunctions in the renal, cardiovascular, reproductive, central nervous systems. In children, IQ deficits are observed at blood lead levels well below 10 μg/dL, and the dose-effect relationship appears to be supra-linear. Other health endpoints associated with greater early-life lead exposure in children include ADHD, conduct disorder, aggression and delinquency, impaired dental health, and delayed sexual maturation. Studies employing neuroimaging modalities such as volumetric, diffusion tensor, and functional MRI are providing insights into the neural bases of the cognitive impairments associated with greater lead exposure.

Environmental contamination has exposed humans to various metal agents, including mercury. It has been determined that mercury is not only harmful to the health of vulnerable populations such as pregnant women and children, but is also toxic to ordinary adults in various ways. For many years, mercury was used in a wide variety of human activities. Nowadays, the exposure to this metal from both natural and artificial sources is significantly increasing. Recent studies suggest that chronic exposure, even to low concentration levels of mercury, can cause cardiovascular, reproductive, and developmental toxicity, neurotoxicity, nephrotoxicity, immunotoxicity, and carcinogenicity. Possible biological effects of mercury, including the relationship between mercury toxicity and diseases of the cardiovascular system, such as hypertension, coronary heart disease, and myocardial infarction, are being studied. As heart rhythm and function are under autonomic nervous system control, it has been hypothesized that the neurotoxic effects of mercury might also impact cardiac autonomic function. Mercury exposure could have a long-lasting effect on cardiac parasympathetic activity and some evidence has shown that mercury exposure might affect heart rate variability, particularly early exposures in children. The mechanism by which mercury produces toxic effects on the cardiovascular system is not fully elucidated, but this mechanism is believed to involve an increase in oxidative stress. The exposure to mercury increases the production of free radicals, potentially because of the role of mercury in the Fenton reaction and a reduction in the activity of antioxidant enzymes, such as glutathione peroxidase. In this review we report an overview on the toxicity of mercury and focus our attention on the toxic effects on the cardiovascular system.

Data dealing with the assessment of heavy metal pollution in road dusts in Jeddah, Saudi Arabia and its implication to human health risk of human exposure to heavy metals, are scarce. Road dusts were collected from five different functional areas (traffic areas (TA), parking areas (PA), residential areas (RA), mixed residential commercial areas (MCRA) and suburban areas (SA)) in Jeddah and one in a rural area (RUA) in Hada Al Sham. We aimed to measure the pollution levels of heavy metals and estimate their health risk of human exposure applying risk assessment models described by United States Environmental Protection Agency (USEPA). Using geo-accumulation index (Igeo), the pollution level of heavy metals in urban road dusts was in the following order Cd > As > Pb > Zn > Cu > Ni > Cr > V > Mn > Co > Fe. Urban road dust was found to be moderately to heavily contaminated with As, Pb and Zn, and heavily to extremely contaminated with Cd. Calculation of enrichment factor (EF) revealed that heavy metals in TA had the highest values compared to that of the other functional areas. Cd, As, Pb, Zn and Cu were severely enriched, while Mn, V, Co, Ni and Cr were moderately enriched. Fe was considered as a natural element and consequently excluded. The concentrations of heavy metals in road dusts of functional areas were in the following order: TA > PA > MCRA > SA > RA > RUA. The study revealed that both children and adults in all studied areas having health quotient (HQ) < 1 are at negligible non-carcinogenic risk. The only exception was for children exposed to As in TA. They had an ingestion health quotient (HQing) 1.18 and a health index (HI) 1.19. The most prominent exposure route was ingestion. The cancer risk for children and adults from exposure to Pb, Cd, Co, Ni, and Cr was found to be negligible (≤1 × 10−6).

Road dust continues to be a major potential reservoir of Pb in the urban environment, and an important potential component of child Pb exposure. This study presents ICP-AES analyses of metals in 72 samples of road dust ( < 250 µm) collected in the urban core of Atlanta, Georgia. In the Downtown area, median Pb concentrations are ~63 mg/kg Pb, with high values of 278 mg/kg. For comparison, median Pb values in a nearby residential neighborhood (also in the urban core) were ~93 mg/kg, with a high of 972 mg/kg. Geospatial variability is high, with significant variation observed over tens to hundreds of meters. Spearman Rank Correlation tests suggest that Pb and other metals (Cu, Ni, V, Zn) are associated with iron and manganese oxide phases in the residential area, as reported in other cities. However, Pb in the Downtown area is not correlated with the others, suggesting a difference in source or transport history. Given these complexities and the expected differences between road dust and soil Pb, future efforts to assess exposure risk should therefore be based on spatially distributed sampling at very high spatial resolution.

Particulate matter of aerodynamic diameter of less than 2.5 µm (PM2.5) is a recognised carcinogen and a priority air pollutant owing to its respirable and toxic chemical components. There is a dearth of information in South Africa on cancer and non-cancer risks of exposure to heavy metal (HM) content of PM2.5. This study determined the seasonal concentration of HM in PM2.5 and the cancer and non-cancer risks of exposure to HM in PM2.5. Ambient PM2.5 was monitored and samples were collected during the winter and summer months in an industrialized area in South Africa. Concentration levels of nine HMs—As, Cu, Cd, Cr, Fe, Mn, Ni, Pb, and Zn—were determined in the PM2.5 samples using inductive coupled optical emission spectrophotometry. The non-cancer and cancer risks of each metal through the inhalation, ingestion and dermal routes were estimated using the Hazard Quotient and Excess Lifetime Cancer Risk (ELCR), respectively, among infants, children, and adults. Mean concentration of each HM-bound PM2.5 was higher in winter than in summer. The probability of the HM to induce non-cancer effects was higher during winter than in summer. The mean ELCR for HMs in PM2.5 (5.24 × 10−2) was higher than the acceptable limit of 10−6 to 10−4. The carcinogenic risk from As, Cd, Cr, Ni, and Pb were higher than the acceptable limit for all age groups. The risk levels for the carcinogenic HMs followed the order: Cr > As > Cd > Ni > Pb. The findings indicated that the concentrations of HM in PM2.5 demonstrated a season-dependent pattern and could trigger cancer and non-cancer health risks. The formulation of a regulatory standard for HM in South Africa and its enforcement will help in reducing human exposure to HM-bound PM2.5.

Industrial effluents with high concentrations of toxic heavy metals are of great concern because of their persistence and non-degradability. However, poor operation and maintenance of wastewater treatment infrastructure is a great concern in South Africa. In this study, physico-chemical parameters and heavy metals (HMs) concentration of wastewater from five different industries, Leeuwkuil wastewater treatment plant (WWTP) inflow and effluent, and Vaal River water samples were monitored between January and September 2017, to investigate the correlation between heavy metal pollution and the location of industries and ascertain the effectiveness of the municipal WWTP. Physico-chemical variables such as pH, biological oxygen demand (BOD), dissolved oxygen (DO), chemical oxygen demand (COD), total dissolved solids (TDS) and electrical conductivity (EC) exhibited both temporal and spatial variations with the values significantly higher in the industrial samples. Inductively coupled plasma optical emission spectrometry (ICP-OES) results also showed that aluminium (Al), copper (Cu), lead (Pb) and zinc (Zn) were significantly higher in industrial effluents (p < 0.05), with only Zn and Al exhibiting significant seasonal variability. Statistical correlation analysis revealed a poor correlation between physicochemical parameters and the HMs compositional quality of wastewater. However, toxic HMs (Zn, Cu and Pb) concentrations in treated wastewater from WWTP were above the permissible limits. Although the WWTP was effective in maintaining most of the wastewater parameters within South African Green drop Standards, the higher Cu, Zn, Pb and COD in its final effluent is a concern in terms of Vaal river health and biological diversity. Therefore, we recommend continuous monitoring and maintenance of the WWTPs infrastructure in the study area.

Classrooms Air Conditioner Filter (CACF) particles represent all of the exposed particles that have migrated to the interior environment. This study was conducted to assess the heavy metals contamination in CACF particles from Jeddah primary schools located in urban, suburban and residential areas; and to evaluate their health risks of children exposure (non-carcinogenic and carcinogenic). Heavy metals levels in CACF particles of schools were in the following order: urban schools > suburban schools > residential schools. Fe, Mn and Zn were the dominant species. Geo-accumulation index (Igeo), contamination factor (CF) and pollution load index (PLI) values indicated that the contamination levels was in the following order Cd > Pb > Zn > As > Cu > Ni > Mn > Cr > Co >V > Fe. School CACF particles was moderately contaminated with As and Zn and moderately to heavily contaminated with Pb and Cd. Enrichment factors (EFs) indicated that Zn, Cd, Pb, As and Cu in CACF particles were severe enriched. The hazard quotient (HQs) and hazards index (HI) values for heavy metals were lower than the acceptable level of one. As, Pb, Cr and Mn were exhibited high non-cancer effects for children. The lifetime cancer risk (LCR) and total lifetime cancer risk (TLCR), HQs and HI values for the different exposure pathways of heavy metals decreased in the following order: ingestion > dermal contact > inhalation. Carcinogenic and non-carcinogenic risk rank order of schools were urban schools > suburban schools > residential schools. The LCR and TLCR of heavy metals was in the following order: Co > Ni >Cr > Cd > As > Pb. The ingestion lifetime cancer risk (LCRing) and TLCR values from exposure to Ni and Cr in urban and suburban schools, Cd in urban schools, and Co in all Jeddah schools only exceed the acceptable range (1 × 10−6–1 × 10−4) Only LCRing and TLCR values from exposure to ∑ carcinogens exceed the acceptable level.