Non-carcinogenic Hazard Quotient Research Articles

Spatial assessment of farmland soil pollution and its potential human health risks in China

Soil pollution severely threatens agro-ecosystem stability. It is important to accurately understand the status of farmland pollution in order to protect national food safety and human health. However, information of the combined pollution level of Chinese farmland soil and associated human health risk at the national scale is relatively lacking. In this study, 5597 samples from 1781 farmland soil sites were obtained from 553 reports and combined into pollution databases of heavy metals, organochlorines, and polycyclic aromatic hydrocarbons. Based on the data obtained, this paper demonstrated the current pollution status of farmland soil, and assessed the subsequent human health risk. Results showed that the combined pollution ratio of Chinese farmland soil was 22.10%, with 1.23% of severe pollution level. Moreover, the total non-carcinogenic hazard quotients of farmland soil pollution were within the safety threshold for adults, but there was a slight non-carcinogenic risk for children. For adults, the ratio of total farmland area to total carcinogenic risk quotients above the safety threshold of 1 × 10−5 was only 1.02%, but for children, the ratio was as high as 20.75%. On the other side, food crop and vegetable plantations were the priority control farmland soil compared to other types. Meanwhile, Yunnan, Hunan, Anhui, Henan, and Liaoning were selected as the priority control provinces due to their severe pollutions and high human health risks. This study has provided a comprehensive pollution and health risk assessment. Furthermore, the spatial distribution might provide as the scientific support for accelerating the mapping of soil pollution in China, as well as developing the policy for the contaminated farmland soil management.

Pollution Characteristics and Occupational Exposure Risk of Heavy Metals in Indoor and Outdoor Ambient Particles at a Scaled Electronic Waste Dismantling Plant, Northwest China

Atmospheric particle samples (PM1.0、PM2.5、PM10) were collected from three sampling sites (indoor and outdoor workplaces of a formal e-waste dismantling plant, and upwind area) in an arid area of Northwest China. The contents of six heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) were analyzed using ICP-OES. Based on this data, the concentration levels, size distribution characteristics, and occupational exposure risks of heavy metals at the indoor and outdoor dismantling workplaces were studied. Particle analysis showed that Zn (4890 ng·m-3 indoors, 1245 ng·m-3 outdoors)、Pb (indoors 1201 ng·m-3, outdoors 240 ng·m-3), and Cu (indoors 1200 ng·m-3, outdoors 110 ng·m-3) showed higher pollution levels indoors and outdoors at the dismantling workplace. Moreover, the indoor concentration was much higher than that outdoors, indicating that the dismantling activity was the main cause of the high levels of heavy metal contamination. The indoor and outdoor air pollution characteristics were closely related to the types of electronic waste dismantled. Occupational exposure risk assessments showed that the total non-carcinogenic hazard quotient (HQ) of the indoor and outdoor dismantling workshops was 1.62×10-3, and 3.60×10-4, respectively, and the carcinogenic risk values were 2.69×10-7 and 2.59×10-9. Cd caused the greatest carcinogenic and non-carcinogenic risks at both indoor and outdoor dismantling workplaces, but it was still far below the limits (1.0) and acceptable ranges (1×10-6) stipulated by U.S. EPA, indicating that the health risks caused by heavy metals were minor or negligible. Heavy metals in the ambient particulate matter released from an adequately equipped and formally managed e-waste dismantling plant would not lead to any public health risk. The sedimentation characteristics of particulate heavy metals in different organs of the human respiratory system exhibited that the smaller the particle size was, the greater the proportion of deposition in the depths of the respiratory system was. Enterprises should make scientific and effective decisions on the respiratory health risks caused by such fine particles to the health of professional workers.

Organophosphate flame retardants in college dormitory dust of northern Chinese cities: Occurrence, human exposure and risk assessment

Organophosphate flame retardants (OPFRs) are widely added to consumer products and building materials, which may pose potential health risk to humans. But information on their contamination and human exposure in the indoor environment especially dormitories in northern China is rare. In this study, twelve OPFRs were investigated in college dormitory dust that collected from Harbin, Shenyang, and Baoding, in northern China. Indoor dust samples were also collected from homes and public microenvironments (PMEs) in Harbin for comparison. The median ∑OPFR concentrations in dormitory dust in Shenyang samples (8690 ng/g) were higher than those in Baoding (6540 ng/g) and Harbin (6190 ng/g). The median ∑OPFR concentrations in home dust (7150 ng/g) were higher than in dormitory and PME dust (5340 ng/g) in Harbin. Tris(2‑chloroethyl) phosphate (TCEP) and tris (2-chloroisopropyl) phosphate (TCIPP) were the most abundant chlorinated OPFRs, while triphenyl phosphate (TPHP) and tris(2‑butoxyethyl) phosphate (TBOEP) were the dominant non-chlorinated OPFRs. The daily intakes of ∑OPFR were estimated, with the median values for female students (2.45 ng/kg-day) higher than those for male students (2.15 ng/kg-day) while were similar to adults (2.45 ng/kg-day) in homes. The estimated daily intakes (EDI) of these OPFRs from indoor dust in Harbin were all below the recommended values. The calculated non-carcinogenic hazard quotients (10−8–10−3) from OPFRs were much lower than the theoretical risk threshold. Meanwhile, carcinogenic risk (CR) of tri‑n‑butyl phosphate (TNBP), TCEP, tris(2‑ethylhexyl) phosphate (TEHP), and tris(1,3‑dichloroisopropyl) phosphate (TDCIPP) were also estimated. The highest carcinogenic risk of TCEP for gender-specific and age-specific category range from 1.75 × 10−7 to 2.46 × 10−7 from exposure to indoor dust indicated a low potential carcinogenic risk for human exposure.

Health Risks of Polychlorinated Biphenyls (PCBs) Levels in Fish and Sediment from River Niger (Onitsha Axis)

ABSTRACTThe health risks of polychlorinated biphenyls (PCBs) levels in fish and sediment from River Niger (Onitsha axis) was investigated. Fish and sediment samples were collected during dry and rainy seasons from upstream and downstream of the river. Extraction was carried out using n-hexane: acetone mixture (50:50) and PCBs were determined using gas chromatography-electron captor detection. Average recovery of 97.67% was obtained for fish and 95.88% for sediment. PCBs concentration and biota-sediment accumulation factor (BSAF) were higher downstream for both seasons. There was no significant difference (P < 0.05) in PCBs concentration between dry and rainy seasons. Concentrations of PCBs in fish were below the Food and Drug Association (FDA, 2018) tolerance level of 2 ppm. Also, noncarcinogenic hazard quotient (HQ) for PCBs congeners in fish samples were ˂1, which indicates no noncarcinogenic health risks from consumption of fish from Niger River. However, carcinogenic HQ for normal fish consumption in children was above 1 in some sample locations but below 1 for adults. Also, carcinogenic HQ for habitual fish consumption was above 1 in some sample locations for both children and adults. There is presence of PCBs in River Niger as a result of anthropogenic activities and industrial discharges, with human risks especially for children.

Human health risks of heavy metals in paddy rice based on transfer characteristics of heavy metals from soil to rice

In order to investigate the transfer and accumulation pathways of heavy metals in cropland ecosystems, an investigation of the geochemical behaviors of heavy metals in soil and rice plants was carried out in the Yangtze River Delta. Soil is one of the biggest reservoirs of heavy metals and affects food safety at the beginning of the food chain. The results of this study demonstrate that heavy metal levels in soil decreased with increasing soil pH, while rice shoots accumulated heavy metals more readily under low soil pH conditions. The non-carcinogenic hazard quotients (HQ) of heavy metals show that health risks for humans were primarily due to Pb and As. Furthermore, cancer risk (Risk) results suggested that ~76% and ~15.7% of cancer risk was caused by Cd and As levels, respectively. Decreasing soil pH enhanced the non-carcinogenic and carcinogenic health risks for the human body. Through exponential change between transfer factor (TFgrain/soil) and soil metals, HQ, a direct monitoring method for rice plants, was built using regression curves. It is proposed that besides condition of soil with high heavy metal concentration, for rice grown with surface soil metals, the safety of the rice product should be monitored when soil metals are under the following levels after harvest: non-carcinogenic risk, As < 20 mg/kg, Pb < 100 mg/kg, Cd < 0.07–0.68 mg/kg and Cu 7.56–30.87 mg/kg; and cancer risk, As < 20 mg/kg, Cd < 4 mg/kg and Cr < 200 mg/kg.

Human Health Risk Assessment of Heavy Metals in Kampala (Uganda) Drinking Water

Levels of aluminium, arsenic, cadmium, chromium, copper, iron, mercury, manganese, nickel, lead and zinc in tap water, groundwater-fed protected spring and bottled water were determined. The cancer and non-cancer risks associated with ingestion of heavy metals (HM) were also assessed for both children and adults. Forty seven water samples obtained from five divisions of Kampala city were analyzed using atomic absorption spectrophotometry. Cancer and non-cancer risks were determined using incremental lifetime cancer risk (ILCR) and non-carcinogenic hazard quotient (HQ), respectively. Lead content was higher than permissible limits (PL) according to East African Standard, World Health Organization, European Union and United States Environmental Protection Agency (USEPA). Arsenic showed minor exceedances above guideline values in tap water and groundwater-fed protected spring, whereas mercury, manganese and nickel were higher than PL. Levels of aluminium, cadmium, chromium, copper, iron, and zinc were below the PL. The lifetime risk of developing cancer through the oral route was greater than the USEPA acceptable level for both children and adults, revealing that exposure to HM in drinking water posed an unacceptable potential cancer risk. Arsenic contributed ca. 90% of the ILCR in tap water and groundwater-fed protected spring. The combined non-cancer risk of the HM expressed as hazard index (HI) was greater than one, with values for children being higher than those for adults. Lead contribution towards HI was in all cases above 90%. These results demonstrate the presence of alarming non-cancer risks for children.

Health hazards of child labor in the leather products and surgical instrument manufacturing industries of Sialkot, Pakistan

Child labor is a major challenge in the developing countries and comprehensive health hazard identification studies on this issue are still lacking. Therefore, the current study is an effort to highlight the health concerns of child labor exposed in the key small scale industries of Sialkot, Pakistan. Our findings revealed jolting levels of heavy metals in the urine, blood, serum, saliva, and hair samples collected from the exposed children. For example, in the urine samples, Cd, Cr, Ni, and Pb were measured at the respective concentrations of 39.17, 62.02, 11.94 and 10.53 μg/L in the surgical industries, and 2.10, 4.41, 1.04 and 5.35 μg/L in the leather industries. In addition, source apportionment revealed polishing, cutting, and welding sections in the surgical industries and surface coating, crusting, and stitching sections in the leather industries were the highest contributors of heavy metals in the bio-matrices of the exposed children, implying the dusty, unhygienic, and unhealthy indoor working conditions. Further, among all the bio-matrices, the hair samples expressed the highest bioaccumulation factor for heavy metals. In accordance with the heavy metal levels reported in the exposed children, higher oxidative stress was found in the children working in the surgical industries than those from the leather industries. Moreover, among heavy metals’ exposure pathways, inhalation of industrial dust was identified as the primary route of exposure followed by the ingestion and dermal contact. Consequently, chemical daily intake (CDI), carcinogenic and non-carcinogenic hazard quotients (HQs) of heavy metals were also reported higher in the exposed children and were also alarmingly higher than the corresponding US EPA threshold limits. Taken all together, children were facing serious health implications in these industries and need immediate protective measures to remediate the current situation.

Bioaccumulation and health risks of heavy metals associated with consumption of rice grains from croplands in Northern India

ABSTRACTThe present study focused on micronutrients and nonessential toxic heavy metals quantification and their bio-concentration in soil–rice system in Haryana, India. Composite samples of rice grains and paddy fields' soil were collected, processed and analyzed for heavy metals. Nutrient and heavy metals' content of paddy fields' soil varied over a wide range, having highest Fe content followed by Cu > Cr > Pb > Ni > Zn > Co > Cd. Most of the metals viz. Fe, Zn, Cu and Co found profusely in rice grains were essential micronutrients. Bio-concentration factors (BCFs) in rice grains were in the following order: Zn (0.11) > Co (0.10) > Cu (0.08) = Cr (0.08) > Ni (0.02) > Pb (0.011) > Cd (0.009) > Fe (0.003), indicating higher accumulation of micronutrients than non-essential toxic heavy metals. Principal component analysis revealed three factors accounting for 70% of the total variance which supported correlation among electrical conductivity (EC)-Na, EC-cation exchange capacity (CEC), CEC-Na, pH-TOC, and BCFCu-BCFZn. Health risk indices anticipated that the grains are safe for consumption as non-carcinogenic hazard quotients were less than unity for all the studied heavy metals.

Concentration of polychlorinated biphenyl (PCB) congeners in the muscle of Clarias gariepinus and sediment from inland rivers of southwestern Nigeria and estimated potential human health consequences

ABSTRACTThe distributions of polychlorinated biphenyl (PCB) congeners were determined in sediment and muscle of the African sharptooth catfish (Clarias gariepinus) from the Ogun and Ona rivers, southwest Nigeria. In addition, the effect of PCB congeners on condition factor (CF) and associated human health risk was assessed using muscle levels for a noncarcinogenic hazard quotient (HQ) calculation. Elevated concentrations of high-molecular-weight (HMW) PCB congeners were detected in sediment and fish downstream of discharge points of both rivers. A significant reduction in fish body weight and CF was observed to correlate with high PCB congener concentrations in the Ona River. A principal component (PC) biplot revealed significant site-related PCB congener distribution patterns for HMW PCB in samples from the Ogun River (71.3%), while the Ona River (42.6%) showed significant PCB congener patterns for low-molecular-weight (LMW) congeners. Biota-sediment accumulation factor (BSAF) was higher downstream for both rivers, presenting PCB congener-specific accumulation patterns in the Ona River. Significant decreases in fish body weight, length and CF were observed downstream compared to upstream in the Ona River. The non-carcinogenic HQ of dioxin-like congener 189 downstream in both rivers exceeded the HQ = 1 threshold for children and adults for both the Ogun and Ona rivers. Overall, our results suggest that industrial discharges contribute significantly to PCB inputs into these rivers, with potential for significant health implications for neighboring communities that utilize these rivers for fishing and other domestic purposes.

Congener specific distribution and health risk assessment of polychlorinated biphenyls in urban soils

Polychlorinated biphenyls (PCBs) were primarily used in transformers and capacitors, lubricants, flame retardants, plasticizers, paint, carbonless papers, etc. These are capable of long-range atmospheric transport and have been designated as persistent organic pollutants by the Stockholm Convention. Due to their characteristic properties, PCBs are found worldwide in all environmental matrices (including human) and biota. Soils are usually considered to be the source as well as sink for environmental pollutants, with cumulative effects of long-range atmospheric transport and local sources. Around the world, comparatively higher concentrations of PCBs have been reported in urban soils than suburban or rural soils. Higher amount of PCBs in urban soils may cause toxicological health risks to urban residents through ingestion, inhalation and skin contact. This paper presents the PCB distribution in soils from Delhi, India, and exposure risk estimates for human health through soil ingestion. The concentration of &amp;Sigma;PCBs ranged between 1.08-100.67 ng g&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; (mean 21.16 ng g&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;&amp;plusmn;5.24 ng g&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;), which was much lower than the Canadian soil quality guideline value of 1.3 mg/kg or 1300 ng g&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;. Human health risk estimates through the soil ingestion pathway were made in terms of lifetime average daily dose (LADD), incremental lifetime cancer risks and non-carcinogenic hazard quotient (HQ). The LADD for Delhi adults and children was 3.02x10&lt;sup&gt;&amp;ndash;8&lt;/sup&gt; mg kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; d&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; and 1.57x10&lt;sup&gt;&amp;ndash;7&lt;/sup&gt; mg kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; d&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;, respectively, which corresponds to toxic equivalent quotients (TEQ) intake of 0.105 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; d&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; (0.735 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; week&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;) and 0.543 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; d&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; (3.801 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; week&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;), respectively. The estimated LADD for Delhi residents was lower than the acceptable intake values recommended by the World Health Organization (1 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; d&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;), the European Commission (14 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;;1 week&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;) and by the Japanese government (4 pg TEQ kg&lt;sup&gt;&amp;ndash;1&lt;/sup&gt; d&lt;sup&gt;&amp;ndash;1&lt;/sup&gt;). The probability of cancer risk ranges from 6.04x10&lt;sup&gt;&amp;ndash;8&lt;/sup&gt; (&amp;Sigma;PCBs) to 1.57x10&lt;sup&gt;&amp;ndash;5&lt;/sup&gt; (&amp;Sigma;TEQ) and 3.13x10&amp;ndash;7 (&amp;Sigma;PCBs) to 8.15x10&amp;ndash;5 (&amp;Sigma;TEQ) for adults and children, respectively, and was within acceptable ranges of 10&lt;sup&gt;&amp;ndash;6&lt;/sup&gt; to 10&lt;sup&gt;&amp;ndash;4&lt;/sup&gt;. The non-carcinogenic risk in terms of health HQ was 0.105 and 0.330 for adults and children, respectively, which was lower than the acceptable limit of 1. The study found lower concentrations of PCBs than guideline values and low health risk estimates through the soil ingestion pathway within acceptable levels, indicating a minimum risk for Delhi residents.

Health risks of organic contaminated soil in an out-of-service oil refinery site

Health risks assessment due to exposure to organic contaminated soil at an oil refinery out of service is conducted in this study by integrating health risk methods of U.S. EPA (United States Environmental Protection Agency), ASTM (American Society for Testing and Materials) and VROM (Ministry of Housing, Spatial Planning and the Environment in Netherlands), with the localized parameters using Chinese demographic characteristics and site features. The monitoring results show that the concentration of benzene, benzo(a)pyrene and benzo(a)anthracene in the soil of the site all exceed their risk screening values, respectively, with pollutants concentrated in soil 0.1–5.5 m beneath the surface. To estimate health risks of the site with the 95% upper confidence limit of the pollution, we focus on three major exposure pathways, namely, oral ingestion, dermal contact and breath inhalation, which indicates carcinogenic risk (CR) and non-carcinogenic hazard quotient (HQ) of the contaminated soil reach 9.59×10−5 and 15.46, respectively, exceeding the acceptable level of 10−5 and 1, posing severe health hazards to the residents at the site.