Health-based Values Research Articles

A comprehensive survey and analysis of international drinking water regulations for inorganic chemicals with comparisons to the World Health Organization's drinking-water guidelines.

The World Health Organization (WHO) has published criteria for determining the quality of drinking water since 1958. Since 1984, these criteria were termed "guidelines" to emphasize that they are not national standards, but rather guidelines for nations to develop their own national standards, which may take into account local environmental, social, economic, and cultural conditions. When calculating guideline values (GVs), the WHO reviews the toxicological literature, calculates a health-based value (HBV), and determines whether the HBV should be adopted as a GV. The WHO also considers aesthetic aspects of drinking water quality, such as taste and the staining of plumbing fixtures, and additionally supplies aesthetic values (AVs) for certain drinking water contaminants. There is no central registry for national drinking water standards, so the degree of variation of national drinking water standards is not known. We examined standards, guidelines, and background documents for all inorganic contaminants published by the WHO from 1958-2022. We also searched for national drinking water standards for all independent countries. We found the WHO currently has 16 GVs, six HBVs without GVs, and six AVs without HBVs or GVs for inorganic drinking water contaminants, excluding disinfection agents and their byproducts. More than half of the point of departure studies used to support these values were published in 2005 or earlier. Ninety-eight percent of the world's population lives in jurisdictions with drinking water standards, and 14 countries directly link their national standards to the current WHO's drinking water guidelines. Lack of transparency (standards available only through purchase) and typographical errors are common problems, especially for resource-limited countries. The WHO drinking water guidelines are crucially important for drinking water safety; they are used for guidance or as official standards throughout the world. It is crucial that they be based on the best available science.

Drinking Water Quality and Public Health in the Kathmandu Valley, Nepal: Coliform Bacteria, Chemical Contaminants, and Health Status of Consumers.

Residents of Nepal's Kathmandu Valley draw drinking water from tube wells, dug wells, and stone spouts, all of which have been reported to have serious water quality issues. In this study, we analyzed drinking water samples from 35 tube wells, dug wells, stone spouts, and municipal tap water for bacterial and chemical contaminants, including total and fecal coliform, aluminum, arsenic, barium, beryllium, boron, cadmium, cobalt, chromium, copper, fluoride, iron, mercury, manganese, molybdenum, nickel, lead, antimony, selenium, thallium, uranium, vanadium, and zinc. We also asked a sampling of households who used these specific water sources to rate the taste of their water, list any waterborne diseases they were aware of, and share basic health information about household members. This survey provided us with information from 146 households and 603 individuals. We found widespread bacterial contamination of water sources, with 94% of sources having detectable total or fecal coliform. Nepal Drinking Water Quality Standards and World Health Organization (WHO) Drinking-Water Guidelines or health-based values were exceeded for aluminum (max = 0.53 mg/L), arsenic (max = 0.071 mg/L), iron (max = 7.22 mg/L), and manganese (max = 3.229 mg/L). The distribution of water sources with high arsenic, iron, and manganese appeared to be associated with floodplain deposits. Mixed effects logistic regression models were used to examine the interactions between social factors and water contaminants and their effects on household members' health. Consumers of water sources with both high and low concentrations of manganese were less likely to have a positive attitude towards school than those whose water sources had moderate concentrations of manganese. Social factors, especially education, played a large role in predicting individual health outcomes. Household taste ratings of drinking water were not correlated with iron or manganese concentrations, suggesting that WHO's reliance on aesthetic criteria for these contaminants instead of formal drinking-water guidelines may not be sufficient to protect public health.

Combined exposure to low level neurotoxic chemicals and child's neuropsychological performance

BACKGROUND AND AIM: Generally, early life exposures to environmental pollutants occur at low levels and their contribution to child’s cognitive abilities, still largely unknown, is a subject of many on-going studies. At low exposures, accounting for multiple neurotoxicants, as well as beneficial elements and genetic variability is important. This study explored prenatal and childhood exposure to trace elements, organophosphate and pyrethroid pesticides and its association with neuropsychological scores. METHODS: Children were recruited in the Ljubljana Maternity Hospital (Slovenia) at birth and were assessed for neuropsychological performance at 7-8 years of age (WISC IV, n=178). Extensive information on life-style was obtained for both periods. Essential and non-essential trace element levels were determined at birth (cord blood), and at follow-up in peripheral whole blood, plasma and urine. Organophosphate and pyrethroid pesticides metabolites were determined in children’s urine at follow-up. RESULTS:Among the potentially neurotoxic substances, 4-nitrophenol, representing parathion exposure, showed negative association with full scale IQ of the children (coeff=-2.09, p=0.022) in a model adjusted for plasma selenium (coeff=16.5, p=0.037) and whole blood copper (coeff=-14.5, p=0.033) (Model R²=0.10, p=0.005). Additional adjustment revealed borderline significant positive effect of breastfeeding in infancy, language classes, and negative effect of watching TV during weekdays, and resulted in a stronger correlation coefficient between 4-nitrophenol and IQ (coeff=-3.03, p=0.004) and stronger overall model (R²=0.27, p0.001). Mercury exposure in prenatal period was positively associated with IQ in the same model (coeff=2.77, p=0.046), most probably indicating beneficial effect of fish consumption during pregnancy. CONCLUSIONS:Although the majority of children had their exposure estimates below the known health-based values, this study demonstrated an importance of evaluating mixed exposures, essential elements as well as child’s cognitive activities along the critical periods of development when estimating their neuropsychological impacts. Continuing this work, paraoxonase genetic polymorphism will be considered and model outcomes will be verified using machine learning approaches. KEYWORDS: trace elements, pesticides, nutrients, neuropsyhological performance

Estimating daily intakes of manganese due to breast milk, infant formulas, or young child nutritional beverages in the United States and France: Comparison to sufficiency and toxicity thresholds

BackgroundAlthough manganese (Mn) is an essential nutrient, recent research has revealed that excess Mn in early childhood may have adverse effects on neurodevelopment. MethodsWe estimated daily total Mn intake due to breast milk at average body weights by reviewing reported concentrations of breast milk Mn and measurements of body weight and breast milk intake at 3 weeks, 4.25 months, 7 months, and 18 months. We compared these figures to the Mn content measured in 44 infant, follow-up, and toddler formulas purchased in the United States and France. We calculated Mn content of formula products made with ultra-trace elemental analysis grade water (0 μg Mn/L) and with water containing 250 μg Mn/L, a concentration which is relatively high but less than the World Health Organization Health-based value of 400 μg Mn/L or the United States Environmental Protection Agency Health Advisory of 350 μg Mn/L. ResultsEstimated mean daily Mn intake from breast milk ranged from 1.2 μg Mn/kg/day (3 weeks) to 0.16 μg Mn/kg/day (18 months), with the highest intakes at the youngest age stage we considered, 3 weeks. Estimated daily Mn intake from formula products reconstituted with 0 μg Mn/L water ranged from 130 μg Mn/kg/day (3 weeks) to 4.8 μg Mn/kg/day (18 months) with the highest intakes at 3 weeks. Formula products provided 28–520 times greater than the mean daily intake of Mn from breast milk for the 4 age stages that we considered. Estimated daily Mn intake from formula products reconstituted with water containing 250 μg Mn/L ranged from 12 μg Mn/kg/day to 170 μg Mn/kg/day, which exceeds the United States Environmental Protection Agency Reference Dose of 140 μg Mn/kg/day for adults. ConclusionsMn deficiency is highly unlikely with exclusive breast milk or infant formula feeding, but established tolerable daily intake levels for Mn may be surpassed by some of these products when following labeled instructions.

Perfluorooctanoic Acid (PFOA): Environmental Sources, Chemistry, Toxicology, and Potential Risks

ABSTRACT Attention regarding perfluoroalkyl and polyfluoroalkyl substances (PFAS) has increased in recent years, due to recognition of widespread environmental presence, recognition of a chemical structure that confers resistance to degradation, and reported health concerns. Historical common exposure sources include food, drinking water, occupational circumstances, and products in commerce (e.g., carpeting, clothing, paper products). Early-2000’s data showed perfluorooctanoic acid (PFOA) was present in blood samples from nearly all the U.S. general population (>99%). Alterations in industrial manufacturing processes, increased regulatory scrutiny, and advanced water treatment options have reduced the reported human body burden of PFAS in the U.S., including for PFOA. Human serum concentrations of PFOA, which do not identify the source(s) of exposure, have exhibited a substantial decrease (~63%) between the 1999–2000 and the 2013–2014 NHANES monitoring by the Centers for Disease Control and Prevention (CDC). With respect to both noncancer and potential cancer effects that may be associated with reported serum levels of PFOA, conclusions regarding an absence of effects, or insufficient information to suggest adverse effects, prevent a consistent conclusion about the occurrence and magnitude of human health effects. In the last several years, a number of state and federal agencies have developed health advisories or guideline values for drinking water exposure that are in the sub-ppb range. In 2016, a USEPA Health Advisory of 0.07 ppb was released, which stands in contrast to 2016 Health-based Values from Health Canada ranging from 0.2 ppb (PFOA) to 30 ppb, and a few other U.S. states with values even less than that of USEPA (e.g., MN, NJ, VT). Further work is necessary to distinguish in transparent fashion between drinking water levels that intentionally are set on a conservative basis to protect human health vs exposure levels that may be associated with tangible adverse effects.

Intra-household agreement of urinary elemental concentrations in Tanzania and Kenya: potential surrogates in case-control studies.

Element deficiencies and excesses play important roles in non-communicable disease etiology. When investigating their roles in epidemiologic studies without prospective designs, reverse-causality limits the utility of transient biomarkers in cases. This study aimed to investigate whether surrogate participants may provide viable proxies by assessing concentration correlations within households. We obtained spot urine samples from 245 Tanzanian and Kenyan adults (including 101 household pairs) to investigate intra-household correlations of urinary elements (As, Ba, Ca, Cd, Co, Cs, Cu, Fe, Li, Mn, Mo, Ni, Pb, Rb, S, Se, Sr, Tl, V, Zn) and concentrations (also available for: Bi, Ce, Sb, Sn and U) relative to external population-levels and health-based values. Moderate-strong correlations were observed for As (r=0.65), Cs (r=0.67), Li (r=0.56), Mo (r=0.57), Se (r=0.68) and Tl (r=0.67). Remaining correlations were <0.41. Median Se concentrations in Tanzania (29 μg/L) and Kenya (24 μg/L) were low relative to 5738 Canadians (59 μg/L). Exceedances (of reference 95th percentiles) were observed for: Co, Mn, Mo, Ni and U. Compared to health-based values, exceedances were present for As, Co, Mo and Se but deficiencies were also present for Mo and Se. For well correlated elements, household members in East African settings provide feasible surrogate cases to investigate element deficiencies/excesses in relation to non-communicable diseases.

Why is the inpatient cost of dying increasing in India?

IntroductionThere is an evidence of increasing inpatient expenditure for decedents. Estimates used to assess the economic burden of out-of-pocket (OOP) healthcare expenditure provide an underestimation for inpatient decedent cases. The aims of this paper are to study the trend and pattern of inpatient decedent expenditure and decipher the reasons behind the increasing cost in India.MethodsUsing three rounds of national level National Sample Survey (NSS) data on morbidity & healthcare conducted during 1995–2015 in India, total and component-wise cost of dying was estimated by the socio-demographic characteristics and types of diseases. Generalised linear model was employed to find the changing effect of inpatient decedents on inpatient expenditure on three-time points.ResultsMore than half among inpatient decedents were elderly. Mean inpatient expenditure for neoplasm, circulatory system-related diseases and external causes of mortality and morbidity increased substantially during these two decades. Mean decedent inpatient expenditure become double, diagnostic and bed charges increased by 243%, 323% respectively during 2004–05 to 2014–15. During 2014–15 average decedents aged 15–59 years spent ₹53599 in last twelve month of their life. Controlling all other potential factors, the inpatient expenditure among decedents increased substantially between 1995–96 and 2014–15.DiscussionOut-of-pocket inpatient health expenditure widened between survivor and decedents in between 1995–2014. Increase in the proportion of elderly, proportion of non-communicable and lifestyle-related diseases, expenses on drugs, diagnostics, bed charges largely private sector expenses were the leading reasons for increasing inpatient decedent expenditure. Age-based risk adjustment and modification of end-of-life care are strongly required, future social insurance based on the health-based value of out-of-pocket expenditure rather than their pure consumption value need to be designed to tackle the burden.

Distribution and Risk Assessment of Perfluorinated Compounds (PFCs) in Major Drinking Water Treatment Plants, Korea

The chemical structures of perfluorinated compounds(PFCs) have unique properties such as thermal and chemical stability that make them useful components in a wide variety of consumer and industrial products. Two of these PFCs, perfluorooctane sulfonate(PFOS) and perfluorooctanoic acid(PFOA), have received attention and were the most commonly detected. In this study it was analyzed the concentrations of 8 PFCs in samples were collected from drinking water treatment plants for 5 years(2012-2016). PFOS and PFOA were also high concentration and frequency. The mean concentrations of PFOA and PFOS were detected 0.0026-0.0069 μg/L and 0.0009-0.0024 μg/L in samples from drinking water treatment plants. These were relatively lower or similar compared to PFOS concentrations in Osaka(Japan). In general, these levels are below health-based values set by international authoritative bodies for drinking water. These results will be serve as the first monitoring data for PFCs in drinking water and be useful for characterizing the concentration distribution and management of PFCs in future studies.

Cyanotoxins: producing organisms, occurrence, toxicity, mechanism of action and human health toxicological risk evaluation.

Cyanobacteria were present on the earth 3.5 billion years ago; since then they have colonized almost all terrestrial and aquatic ecosystems. They produce a high number of bioactive molecules, among which some are cyanotoxins. Cyanobacterial growth at high densities, forming blooms, is increasing in extension and frequency, following anthropogenic activities and climate changes, giving rise to some concern for human health and animal life exposed to cyanotoxins. Numerous cases of lethal poisonings have been associated with cyanotoxins ingestion in wild animal and livestock. In humans few episodes of lethal or severe human poisonings have been recorded after acute or short-term exposure, but the repeated/chronic exposure to low cyanotoxin levels remains a critical issue. The properties of the most frequently detected cyanotoxins (namely, microcystins, nodularins, cylindrospermopsin and neurotoxins) are here critically reviewed, describing for each toxin the available information on producing organisms, biosynthesis/genetic and occurrence, with a focus on the toxicological profile (including kinetics, acute systemic toxicity, mechanism and mode of action, local effects, repeated toxicity, genotoxicity, carcinogenicity, reproductive toxicity; human health effects and epidemiological studies; animal poisoning) with the derivation of health-based values and considerations on the risks for human health.

Occupational exposure limit for silver nanoparticles: considerations on the derivation of a general health-based value

With the increased production and widespread commercial use of silver nanoparticles (AgNPs), human and environmental exposures to silver nanoparticles are inevitably increasing. In particular, persons manufacturing and handling silver nanoparticles and silver nanoparticle containing products are at risk of exposure, potentially resulting in health hazards. While silver dusts, consisting of micro-sized particles and soluble compounds have established occupational exposure limits (OELs), silver nanoparticles exhibit different physicochemical properties from bulk materials. Therefore, we assessed silver nanoparticle exposure and related health hazards in order to determine whether an additional OEL may be needed. Dosimetric evaluations in our study identified the liver as the most sensitive target organ following inhalation exposure, and as such serves as the critical target organ for setting an occupational exposure standard for airborne silver nanoparticles. This study proposes an OEL of 0.19 μg/m3 for silver nanoparticles derived from benchmark concentrations (BMCs) from subchronic rat inhalation toxicity assessments and the human equivalent concentration (HEC) with kinetic considerations and additional uncertainty factors. It is anticipated that this level will protect workers from potential health hazards, including lung, liver, and skin damage.

Occurrence of perfluoroalkyl acids in environmental waters in Vietnam

This is the first nationwide study of perfluoroalkyl acids (PFAAs) in environmental waters in Vietnam. Twenty-eight river water and 22 groundwater samples collected in four major cities and 14 river water samples from the Red River were screened to investigate the occurrence and sources of 16 PFAAs. Perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), and perfluorononanoic acid (PFNA) were the most prevalent of 11 detected PFAAs with maximum concentrations in urban river water of 5.3, 18 and 0.93ngL−1, respectively, and in groundwater of 8.2, 4.5 and 0.45ngL−1, respectively. PFAAs in the Red River water were detected at low levels. PFAA concentrations in river water were higher in the rainy season than in the dry season, possibly due to storm water runoff, a common phenomenon in Southeast Asian countries. The highest concentrations of PFAAs in river water were observed in samples from highly populated and industrialized areas, perhaps sourced from sewage. The PFAA concentrations observed were similar to those in other Southeast Asian countries, but lower than in developed nations. From the composition profiles of PFAAs, industrial products containing PFAAs imported from China and Japan might be one of the major sources of PFAAs in the Vietnamese aquatic environment. According to the health-based values and advisory issued by the United States Environmental Protection Agency (USEPA), the concentrations of detected PFAAs in this study do not pose an immediate health risk to humans and aquatic organisms.

Molybdenum distributions and variability in drinking water from England and Wales.

An investigation has been carried out of molybdenum in drinking water from a selection of public supply sources and domestic taps across England and Wales. This was to assess concentrations in relation to the World Health Organization (WHO) health-based value for Mo in drinking water of 70 μg/l and the decision to remove the element from the list of formal guideline values. Samples of treated drinking water from 12 water supply works were monitored up to four times over an 18-month period, and 24 domestic taps were sampled from three of their supply areas. Significant (p < 0.05) differences were apparent in Mo concentration between sources. Highest concentrations were derived from groundwater from a sulphide-mineralised catchment, although concentrations were only 1.5 μg/l. Temporal variability within sites was small, and no seasonal effects (p > 0.05) were detected. Tap water samples collected from three towns (North Wales, the English Midlands, and South East England) supplied uniquely by upland reservoir water, river water, and Chalk groundwater, respectively, also showed a remarkable uniformity in Mo concentrations at each location. Within each, the variability was very small between houses (old and new), between pre-flush and post-flush samples, and between the tap water and respective source water samples. The results indicate that water distribution pipework has a negligible effect on supplied tap water Mo concentrations. The findings contrast with those for Cu, Zn, Ni, Pb, and Cd, which showed significant differences (p < 0.05) in concentrations between pre-flush and post-flush tap water samples. In two pre-flush samples, concentrations of Ni or Pb were above drinking water limits, although in all cases, post-flush waters were compliant. The high concentrations, most likely derived from metal pipework in the domestic distribution system, accumulated during overnight stagnation. The concentrations of Mo observed in British drinking water, in all cases less than 2 μg/l, were more than an order of magnitude below the WHO health-based value and suggest that Mo is unlikely to pose a significant health or water supply problem in England and Wales.

Occurrence of molybdenum in British surface water and groundwater: Distributions, controls and implications for water supply

Data for Mo in British surface water and groundwater collated from a number of databases show that concentrations are in most cases low, of the order of 2μg/L or less. However, variability is large and sporadic high values are found in both streamwaters and groundwaters. Data for some 11,600 British streamwater samples indicate a 10–90th percentile range of 0.08–2.44μg/L with a median of 0.57μg/L and maximum observation of 230μg/L. High values tend to be from streams on clay-rich formations and sulphide-mineralised bedrock and streams affected by localised urban and industrial contamination. Monitored lowland river waters also typically have median concentrations <1μg/L although higher values are present in a number of urban/industrialised English rivers. Highest observed concentrations (median 20μg/L), occur under low-flow conditions in a river system from an urban, industrial area of NE England and are likely the products of industrial contamination and mine drainage. Concentrations in 96 upland lakewater samples from NW England are universally 0.1μg/L or less. Data for 1735 groundwater samples from across Britain have a 10–90th percentile range for Mo of 0.035–1.80μg/L with a median of 0.20μg/L and maximum observation of 89μg/L. Relatively high values derive from some Lower Cretaceous greensand, Carboniferous limestone and mudstone (Coal Measures) aquifers, particularly under anaerobic conditions. Release from Fe oxides and possibly Mn oxides by reductive dissolution is a likely mechanism for the concentrations. Under more rarely observed sulphate-reducing conditions in British aquifers, concentrations of Mo diminish, likely due to sequestration by precipitating sulphide minerals. The observed ranges in aqueous samples indicate that most water sources in Britain have Mo concentrations more than an order of magnitude below the WHO health-based value for Mo in drinking water (70μg/L). Such sources are unlikely to pose a risk to drinking water from the current WHO guidance, provided those impacted locally by mining or other industrial contamination are avoided.

Dietary exposure of 18-month-old Guadeloupian toddlers to chlordecone

Chlordecone is an organochlorine insecticide used in the French West Indies until 1993. Toddlers are expected to be differently exposed than older children and adults. The dietary exposure to chlordecone of 18-month-old Guadeloupian toddlers was assessed through different scenarios depending on whether the subjects live on a soil-contaminated place or not and on their supply habits. Food contamination data came from the RESO study performed in 2005–2006. Consumption data derived from a dietary survey conducted in 2005–2008. Results were compared to those of other age groups. Chronic dietary exposures to chlordecone were estimated in a range of 0.018–0.051μg/kg bw/day (P95: 0.044–0.096) for toddlers living in a non contaminated area and between 0.045–0.078μg/kg bw/day (P95: 0.110–0.144) for toddlers living in a contaminated area. The probability of exceeding the chronic health-based value of 0.5μg/kg bw/day was null. These results suggest that 18-month-old toddlers are less exposed than groups aged over 3years old. This can be explained by their consumption pattern mostly based on milk and fruits, which are not highly contaminated by chlordecone. The acute health-based value of 10μg/kg bw/day could be exceeded when consuming of highly contaminated taros, showing the importance of regulatory maximum limit.

World Health Organization Discontinues Its Drinking-Water Guideline for Manganese

Background: The World Health Organization (WHO) released the fourth edition of Guidelines for Drinking-Water Quality in July 2011. In this edition, the 400-µg/L drinking-water guideline for manganese (Mn) was discontinued with the assertion that because “this health-based value is well above concentrations of manganese normally found in drinking water, it is not considered necessary to derive a formal guideline value.”Objective: In this commentary, we review the WHO guideline for Mn in drinking water—from its introduction in 1958 through its discontinuation in 2011.Methods: For the primary references, we used the WHO publications that documented the Mn guidelines. We used peer-reviewed journal articles, government reports, published conference proceedings, and theses to identify countries with drinking water or potential drinking-water supplies exceeding 400 µg/L Mn and peer-reviewed journal articles to summarize the health effects of Mn.Discussion: Drinking water or potential drinking-water supplies with Mn concentrations > 400 µg/L are found in a substantial number of countries worldwide. The drinking water of many tens of millions of people has Mn concentrations > 400 µg/L. Recent research on the health effects of Mn suggests that the earlier WHO guideline of 400 µg/L may have been too high to adequately protect public health.Conclusions: The toxic effects and geographic distribution of Mn in drinking-water supplies justify a reevaluation by the WHO of its decision to discontinue its drinking-water guideline for Mn.

Use of the Reciprocal Calculation Procedure for Setting Workplace Emergency Action Levels for Hydrocarbon Mixtures and their Relationship to Lower Explosive Limits

This paper proposes a novel use of the reciprocal calculation procedure (RCP) to calculate workplace emergency action levels (WEALs) for accidental releases of hydrocarbon mixtures. WEALs are defined here as the concentration in air that area monitors should alarm at to provide adequate warning and be sufficiently protective of health to allow at least enough time to don respiratory protective equipment (RPE) and escape. The rationale for the approach is analysed, and ways of defining suitable substance group guidance values (GVs) for input into the RCP are considered and compared. WEAL GVs could be based on: 3× RCP GVs (i.e. using the 3× rule), the 5× RCP GVs (i.e. using the 5× rule for calculating ceiling values), emergency exposure limits, or immediately dangerous to life or health values (IDLHs). Of these, the method of choice is to base WEAL GVs on health-based IDLH values, which were developed for emergency situations in the workplace. However, IDLHs have only been set for 11 hydrocarbons, so the choice of GVs is also informed by comparison with possible GVs based on the other approaches. Using the proposed GVs, WEALs were calculated for various hydrocarbon mixtures, and the way they vary with the composition of the mixture was examined. Also, the level of health protection given by the current practice of setting emergency area alarms in the oil and gas industry at 10% of the lower explosive limit (LEL) was tested by comparing this with the WEAL. In the event of an accidental release, this comparison suggests that, provided that aromatics constitute <50% of the mixture, an alarm set at 10% LEL should provide adequate warning and be sufficiently protective of health to at allow at least enough time to don RPE and escape. In the absence of better information or specific acute toxicity concerns (such as the presence of hydrogen sulphide), it is proposed that the WEALs be used as a guide for assessing the adequacy of area alarm levels in respect of warning of an acute health risk. This work is exploratory (e.g. other rationales for setting GVs are possible) and the approach needs testing on further real-life samples. Although not explored here, the RCP approach may also lend itself to the calculation of in-house short-term exposure limits for hydrocarbon mixtures and other mixtures where the acute toxic end points of the components are similar.

Using an Integrated Food Chain Model as an Instrument to Derive Health-Based Threshold Values for Atmospheric Deposition of PCDD/F and DL-PCBs

Using an Integrated Food Chain Model as an Instrument to Derive Health-Based Threshold Values for Atmospheric Deposition of PCDD/F and DL-PCBs

Perfluorooctane sulphonate and perfluorooctanoic acid in drinking and environmental waters

Perfluorooctane sulphonate (PFOS) and perfluorooctanoic acid (PFOA) are chemicals that have been used for many years as surfactants in a variety of industrial and consumer products. Owing to their persistent, bioaccumulative and toxic (PBT) characteristics, PFOS has been phased out by its principal producer and the use of PFOA has been reduced. This PBT potential and a number of pollution incidents have led in recent years to an increase in studies surveying the concentrations of PFOS and PFOA in environmental waters worldwide. This paper reviews the results of these studies, as well as the monitoring that was conducted after the pollution incidents. The results of surveys suggest that PFOS and PFOA are found in environmental waters worldwide at low levels. In general, these levels are below health-based values set by international authoritative bodies for drinking water. There have been limited measurements of these chemicals in drinking water, but again these are below health-based values, except in some cases following pollution incidents. Monitoring studies suggested that where PFOS and PFOA were detected, they were at similar levels in both source and drinking water, suggesting that drinking water treatment does not remove these chemicals. However, new data show that PFOS and PFOA are effectively removed by granular activated carbon absorbers in practice. Further research is required on the newer perfluorinated chemicals that appear to be safer, but their degradation products have not as yet been fully studied.

Perfluorinated Compounds in Tap Water from China and Several Other Countries

The recent development of a sensitive and accurate analytical method for the analysis of 20 perfluorinated compounds (PFCs), including several short-chain PFCs, has enabled their quantification in tap water collected in China, Japan, India, the United States, and Canada between 2006 and 2008. Of the PFCs measured, PFOS, PFHxS, PFBS, PFPrS, PFEtS, PFOSA, N-EtFOSAA, PFDoDA, PFUnDA, PFDA, PFNA, PFHpA, PFHxA, PFPeA, PFBA, and PFPrA were found at detectable concentrations in the tap water samples. The water samples from Shanghai (China) contained the greatest concentrations of total PFCs (arithmetic mean = 130 ng/L), whereas those from Toyama (Japan) contained only 0.62 ng/L. In addition to PFOS and PFOA, short-chain PFCs such as PFHxS, PFBS, PFHxA, and PFBA were found to be prevalent in drinking water. According to the health-based values (HBVs) and advisory guidelines derived for PFOS, PFOA, PFBA, PFHxS, PFBS, PFHxA, and PFPeA by the U.S.EPA and the Minnesota Department of Health, tap water may not pose an immediate health risk to consumers.

Recent policy and technical developments in biological monitoring in the United Kingdom

In 1996 the United Kingdom's Health and Safety Executive introduced biological monitoring guidance values for six substances, butoxyethanol, N,N-dimethylacetamide, lindane, methylene-bis(2-chloroaniline), mercury and methylenedianiline. These guidance values were set as either health-based values or hygiene-based values calculated according to the 90th percentile (benchmark concept). Recent technical developments from the Health and Safety Laboratory are described in this paper and include: (i) the use of breath analysis as a useful non-invasive routine monitoring technique; (ii) flow cytometry as a means for measuring different patterns of immune cell activation from workers exposed to respiratory sensitisers when compared with those exposed to chemical irritants; (iii) the use of molecular techniques to explore the possible role of individual susceptibility in the development and severity of glomerulonephritis; (iv) the development of expert systems for predicting the skin permeability of chemicals, and respiratory and skin sensitisation.