Office Of Environmental Health Hazard Assessment Research Articles

Dermal exposure and hair dye: Assessing potential bladder cancer risk from permanent hair dye

Hair dye products include a range of chemicals, depending on the type and color. A common primary intermediate compound used to achieve the permanent effect of hair dye is para-phenylenediamine (PPD). 4-aminobiphenyl (4-ABP) has reportedly been found as a trace contaminant (presumably from the para-phenylenediamine [PPD] ingredient) in consumer permanent hair dye. While several regulatory agencies have designated 4-ABP as a human bladder carcinogen based on evidence in humans and experimental animals, only the Office of Environmental Health Hazard Assessment (OEHHA) have established a cancer risk value for 4-ABP of 0.03 μg/day based on liver tumors developed in mice. A hypothetical dermal risk assessment was performed to estimate the bladder cancer risk associated with exposure to 4-ABP from personal use of permanent hair dye potentially containing incidental 4-ABP. Previously published laboratory analyses characterizing 4-ABP concentrations in consumer hair dyes indicate the concentrations can range from below the limit of detection to 8120 ppb. Precautionary estimates of human scalp surface area, maximum skin adherence, hair dye retention factor, and percent dermal absorption were used to estimate the daily systemic exposure doses (SEDs) from dermal application of hair dye. The estimated SEDs ranged from 0.05 to 3000 pg/day. A margin of safety (MOS) was calculated as the ratio of the NSRL to the SED and ranged from 10 to 570,000. The results of this study suggest that there is no indication of increased risk of bladder cancer in humans from exposure to 4-ABP in consumer hair dye, especially as it is extremely unlikely that a consumer would use permanent hair dye on a daily basis (as this assessment models).

Animal evidence considered in determination of cannabis smoke and Δ9 -tetrahydrocannabinol as causing reproductive toxicity (developmental endpoint); Part I. Somatic development.

On December 11, 2019, California's Developmental and Reproductive Toxicant Identification Committee (DARTIC) met to consider the addition of cannabis smoke and Δ9 -THC to the Proposition 65 list as causing reproductive toxicity (developmental endpoint). As the lead state agency for implementing Proposition 65, the Office of Environmental Health Hazard Assessment (OEHHA) reviewed and summarized the relevant scientific literature in the form of a hazard identification document (HID). Here we provide reviews based on the HID: shortened, revised, and reformatted for a larger audience. While the HID included both human and animal data, this set of three reviews will highlight the animal-derived data pertaining to somatic development (Part I), neurodevelopmental effects (Part II), and proposed neurodevelopmental mechanisms of action (Part III). Endogenous cannabinoids (eCBs) and their receptors serve many critical functions in normal development. Δ9 -THC can interfere with these functions. Mechanistic studies employed techniques including: blocking Δ9 -THC binding to endocannabinoid (EC) receptors, inhibiting Δ9 -THC metabolism, and/or using animals expressing knockout mutations of EC receptors. Apical somatic effects of cannabis smoke or Δ9 -THC reported in whole animal studies included decreases in offspring viability and growth. Mechanistic studies discussed in Part I focused on Δ9 -THC effects on early embryos and implantation, immune development, and bone growth. In reaching its decision to list cannabis and Δ9 -THC as a developmental toxicant under California's Proposition 65, the DARTIC considered biological plausibility and the consistency of mechanistic information with effects reported in human and whole animal studies.

Investigating aldehyde and ketone compounds produced from indoor cooking emissions and assessing their health risk to human beings

Aldehyde and ketone compounds are ubiquitous in the air and prone to adverse effects on human health. Cooking emission is one of the major indoor sources. Aiming to evaluate health risks associated with inhalation exposure to aldehyde and ketone compounds, 13 carbonyl compounds (CCs) released from heating 5 edible oils, 3 seasonings, and 2 dishes were investigated in a kitchen laboratory. For the scenarios of heating five types of oil, aldehydes accounted for 61.1%-78.0% of the total emission, mainly acetaldehyde, acrolein and hexanal. Comparatively, heating oil with added seasonings released greater concentrations of aldehyde and ketone compounds. The concentration enhancement of larger molecular aldehydes was significantly greater. The emission factors of aldehyde and ketone compounds for cooking the dish of chili fried meat were much greater compared to that of tomato fried eggs. Therefore, food materials also had a great impact on the aldehyde and ketone emissions. Acetone and acetaldehyde were the most abundant CCs in the kitchen. Acrolein concentrations ranged from 235.18 to 498.71 µg/m3, which was about 100 times greater compared to the guidelines provided by Office of Environmental Health Hazard Assessment (OEHHA). The acetaldehyde inhalation for adults was 856.83-1515.55 µg and 56.23-192.79 µg from exposure to chili fried meat and tomato fried eggs, respectively. This exceeds the reference value of 90 µg/day provided by OEHHA. The findings of this study provided scientific evidences for the roles of cooking emissions on indoor air quality and human health.

Statewide Evaluation of the California Medical Supervision Program Using Cholinesterase Electronic Laboratory Reporting Data: An Update

The California Medical Supervision Program is designed to protect agricultural workers from overexposure to Toxicity Category I and II organophosphate (OP) and carbamate (CB) pesticides by routinely monitoring their blood cholinesterase (ChE) activity levels. ChE testing is conducted at State-approved laboratories and electronically reported to the Department of Pesticide Regulation (DPR) and the Office of Environmental Health Hazard Assessment (OEHHA) for review. In 2015, OEHHA and DPR evaluated the effectiveness of the Program by analyzing ChE data from pesticide handlers performed between 2011 and 2013, which revealed issues with the data quality that hindered the evaluation process. Several interventions have been implemented since then to improve data quality and the overall function of the Program. A new evaluation was conducted in 2020 to 2021 using data from 2014 to 2019 to determine the effectiveness of the Program, Program compliance, and efficacy of the interventions. The analysis revealed similar data quality issues identified in the last evaluation, however, an improvement in data quality was observed. The number of individuals with ChE depression below the action level threshold have decreased in recent years, corresponding to the implementation of certain interventions, indicating that the effectiveness of the Program has improved. Spatial and temporal analysis showed the proportion of pre-exposure baseline tests inversely correlated with pesticide use data while routine follow-up ChE test results showed a positive correlation, indicating a high degree of Program compliance across the state. Major improvements in the data cleaning and analysis since the last evaluation have also improved the evaluation: pesticide handlers under the Program were able to be identified with more certainty and ChE depressions were able to be calculated with increased accuracy. However, further improvements to the data collection process could enhance future evaluations of the Program.

Seasonal and diurnal patterns of outdoor formaldehyde and impacts on indoor environments and health

Formaldehyde is concerned as an important indoor carcinogen. While contribution of outdoor formaldehyde to indoor concentration is recognized, long-term measurement about its impact on indoor environments remain missing. We measured both outdoor and indoor formaldehyde concentrations for over one year in Nanjing (east-central China) and calculated the outdoor/indoor (O/I) ratios. 64.8% of the measured outdoor concentration have exceeded the chronic reference exposure criteria of 0.009 mg/m3 set by Office of Environmental Health Hazard Assessment (OEHHA). The outdoor concentration was highest in summer with median value of 0.020 mg/m3 and lowest in spring with median value of 0.009 mg/m3. Diurnally, outdoor formaldehyde concentration was highest at noon with median value of 0.013 mg/m3 and lowest at night with median value of 0.01 mg/m3. Health analysis revealed that cancer risk by exposure to this concentration level is 1.6 × 10−4, higher than threshold limit of 10−6. In addition, the median O/I ratios are 0.18 and 0.27 in two offices, indicating that outdoor formaldehyde contributes to indoor concentrations by about one quarter. The change of O/I ratio also shows a similar seasonal and diurnal trend as outdoor concentrations (highest in the summer in a year and at noon in a day). Outdoor formaldehyde concentration is therefore not negligible as a contributor to indoor concentration, especially as indoor concentration limit gets continuously lowered. This factor should be taken into account in indoor air quality design and maintenance.

Health Effects of Naphthalene Exposure: A Systematic Evidence Map and Analysis of Potential Considerations for Dose-Response Evaluation.

Background:Naphthalene is a polycyclic aromatic hydrocarbon that has been associated with health effects, including cancer. As the state of the science on naphthalene toxicity continues to evolve, updated toxicity reference value(s) may be required to support human health risk assessment.Objectives:We present a systematic evidence map of studies that could be used to derive toxicity reference value(s) for naphthalene.Methods:Human and animal health effect studies and physiologically based pharmacokinetic (PBPK) models were identified from a literature search based on populations, exposures, comparators, and outcomes (PECO) criteria. Human and animal studies meeting PECO criteria were refined to a smaller subset considered most informative for deriving chronic reference value(s), which are preferred for assessing risk to the general public. This subset was evaluated for risk of bias and sensitivity, and the suitability of each study for dose–response analysis was qualitatively assessed. Lowest observed adverse effect levels (LOAELs) were extracted and summarized. Other potentially relevant studies (e.g., mechanistic and toxicokinetic studies) were tracked as supplemental information but not evaluated further. Existing reference values for naphthalene are also summarized.Results:We identified 26 epidemiology studies and 16 animal studies that were considered most informative for further analysis. Eleven PBPK models were identified. The available epidemiology studies generally had significant risk of bias and/or sensitivity concerns and were mostly found to have low suitability for dose–response analysis due to the nature of the exposure measurements. The animal studies had fewer risk of bias and sensitivity concerns and were mostly found to be suitable for dose–response analysis.Conclusion:Although both epidemiological and animal studies of naphthalene provide weight of evidence for hazard identification, the available animal studies appear more suitable for reference value derivation. PBPK models and mechanistic and toxicokinetic data can be applied to extrapolate these animal data to humans, considering mode of action and interspecies metabolic differences. https://doi.org/10.1289/EHP7381

Inhalation of two Prop 65-listed chemicals within vehicles may be associated with increased cancer risk

Chemicals are listed on California’s Proposition 65 (Prop 65) for their potential to cause cancer, birth defects or other reproductive harm, and certain chemicals from this list are often detected within interior vehicle dust and air. Therefore, this study examined the potential risk associated with five Prop 65-listed chemicals detected within vehicle interiors: benzene, formaldehyde, di (2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and tris(1,3-dichloro-2-propyl)phosphate (TDCIPP). Exposure estimates based on time spent within a vehicle were derived from a meta-analysis of estimated concentrations from the literature. Regulatory levels established by the California Office of Environmental Health Hazard Assessment (OEHHA) were then used to generate percent reference doses (%RfDs) for chemical-specific daily doses as well as determine the probability of risk (exceedance probability) as a function of %RfD for each chemical-specific daily dose. Based on our meta-analysis, benzene and formaldehyde were detected in vehicle interior air whereas DEHP, DBP and TDCIPP were detected in vehicle interior dust. Benzene and formaldehyde were the only two chemicals with an estimated %RfD > 100 across any of the commute times. For commute times of 20 min or longer, the %RfD was > 100 for maximum exposures based on the “maximum allowable daily level” for benzene, and for 95th-percentile exposures based on the “no significant risk level” for benzene and formaldehyde. Furthermore, the probability of exceeding 100% RfD was highest for cancer risks associated with benzene, followed by cancer risks associated with formaldehyde and the risk of reproductive and developmental toxicity associated with benzene. Lastly, within the entire state of California, the percent of commuters with a 10% probability of exceeding cancer risk associated with benzene or formaldehyde exposure was 78% and 63%, respectively. Overall, our study raises concerns about the potential risk associated with inhalation of benzene and formaldehyde for people who spend a significant amount of time in their vehicles, an issue that is especially pertinent to traffic-congested areas where people have longer commutes.

Assessment of the biochemical pathways for acetaminophen toxicity: Implications for its carcinogenic hazard potential

In 2019 California's Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. In parallel with this review, herein we evaluated the mechanistic data related to the steps and timing of cellular events following therapeutic recommended (≤4 g/day) and higher doses of acetaminophen that may cause hepatotoxicity to evaluate whether these changes indicate that acetaminophen is a carcinogenic hazard. At therapeutic recommended doses, acetaminophen forms limited amounts of N-acetyl-p-benzoquinone-imine (NAPQI) without adverse cellular effects. Following overdoses of acetaminophen, there is potential for more extensive formation of NAPQI and depletion of glutathione, which may result in mitochondrial dysfunction and DNA damage, but only at doses that result in cell death – thus making it implausible for acetaminophen to induce the kind of stable, genetic damage in the nucleus indicative of a genotoxic or carcinogenic hazard in humans. The collective data demonstrate a lack of a plausible mechanism related to carcinogenicity and are consistent with rodent cancer bioassays, epidemiological results reviewed in companion manuscripts in this issue, as well as conclusions of multiple international health authorities.

Application of the DILIsym® Quantitative Systems Toxicology drug-induced liver injury model to evaluate the carcinogenic hazard potential of acetaminophen

In 2019, the California Office of Environmental Health Hazard Assessment (OEHHA) initiated a review of the carcinogenic hazard potential of acetaminophen. The objective of the analysis herein was to inform this review by assessing whether variability in patient baseline characteristics (e.g. baseline glutathione (GSH) levels, pharmacokinetics, and capacity of hepatic antioxidants) leads to potential differences in carcinogenic hazard potential at different dosing schemes: maximum labeled doses of 4 g/day, repeated doses above the maximum labeled dose (>4–12 g/day), and acute overdoses of acetaminophen (>15 g). This was achieved by performing simulations of acetaminophen exposure in thousands of diverse virtual patients scenarios using the DILIsym® Quantitative Systems Toxicology (QST) model. Simulations included assessments of the dose and exposure response for toxicity and mode of cell death based on evaluations of the kinetics of changes of: GSH, N-acetyl-p-benzoquinone-imine (NAPQI), protein adducts, mitochondrial dysfunction, and hepatic cell death. Results support that, at therapeutic doses, cellular GSH binds to NAPQI providing sufficient buffering capacity to limit protein adduct formation and subsequent oxidative stress. Simulations evaluating repeated high-level supratherapeutic exposures or acute overdoses indicate that cell death precedes DNA damage that could result in carcinogenicity and thus acetaminophen does not present a carcinogenicity hazard to humans at any dose.

Derivation of a No significant risk level (NSRL) for acrylamide

Acrylamide is included on the State of California’s Proposition 65 list as a carcinogen. Acrylamide is found in cigarette smoke and in many types of foods, including breads, cereals, coffee, cookies, French fries, and potato chips. In 1990, California’s Office of Environmental Health Hazard Assessment (OEHHA) established a no significant risk level (NSRL) of 0.2 μg/day for acrylamide. Since then, multiple cancer studies have been published. In this report, we developed an updated NSRL for acrylamide. Using benchmark dose modeling and a weight-of-evidence, non-threshold approach to identify the most sensitive species, cancer slope factors (CSFs) were derived based on combined incidences of statistically significant neoplastic lesions in the Harderian gland, lung, and stomach in male mice. We then used a toxicokinetic (TK)-based scaling approach to convert the animal CSF to a human equivalent CSF, which served as the basis for the NSRL of 1.1 μg/day at the cancer risk level of 1 in 100,000. This NSRL can be used in quantitative exposure assessments to assess compliance with Proposition 65 to ascertain either the need for or exemption from the Proposition 65 labeling requirement and drinking water discharge prohibition.

Quantitative and semi-quantitative risk assessment of occupational exposure to lead among electrical solderers in Neyshabur, Iran.

Lead is one of the most widely used elements in the world. Lead can cause acute and chronic complications such as abnormal hemoglobin synthesis, kidney damage, abortion, nervous system disorders, male infertility, loss of learning ability, behavioral disorders, and even death. The aim of this study was to carry out quantitative and semi-quantitative risk assessments of exposure to lead among the solderers of the Neyshabur electronics industry. This cross-sectional, descriptive, and analytical study was conducted in 2017 and 2018 on 40 female soldering workers exposed to lead. Semi-quantitative risk assessment was carried out according to the Singapore Health Department and quantitative risk assessment according to the Office of Environmental Health Hazard Assessment (OEHHA) method. The average occupational exposure to lead in the electronics manufacturing industry was 93.89 ± 33.40 μg m-3 with a range from 9 to 150 μg m-3. Occupational exposure to lead in the industrial groups of initial soldering with an average of 130.37 ± 40.23 μg m-3 and cutting wires, electroplating, and coating bare parts with an average of 110.24 ± 30.11 μg m-3 was higher than the secondary soldering groups with an average of 90.78 ± 20.22 and shift supervisors with an average of 43.86 ± 10.97 μg m-3. The mean excess lifetime cancer risk (ELCR) was 0.11 per 1000 people and the mean non-carcinogenic risk (HQ) was 7.20. The results of this study indicate that there is a risk of non-carcinogenic complications among electronic solderers. Therefore, managers and employers should reduce lead exposure through engineering controls (substituting lead-free alloys, efficient ventilation) and management strategies such as reducing exposure hours.

Comparison of carcinogenic potency across life stages: implications for the assessment of transplacental cancer risk

ABSTRACTCancer development from in utero exposure has been documented for a variety of agents with the most commonly studied compounds exhibiting mutagenic and genotoxic carcinogen properties. Age-dependent adjustment factors (ADAFs) are applied by the US Environmental Protection Agency to many such carcinogens when assessing cancer risk from early postnatal (PN) exposures; however, this approach has not been widely considered for transplacental (TP) exposure. To explore this question and further evaluate prenatal susceptibility a database of early life animal studies developed by California Office of Environmental Health Hazard Assessment (OEHHA) enhanced with additional literature searching was evaluated. Nine genotoxic carcinogens and one mixture (cigarette smoke) have data available via TP only, PN only and adult-only protocols. Potency comparisons across these lifestages displayed similarly greater potency in male liver and brain compared to adult-only exposure. Both TP and PN exposures were not markedly different than adult-only for other targets such as female liver and blood-borne tumors. Similarity in TP and PN targets and potency for carcinogen action suggests that a 10-fold ADAF may be applied for TP exposure as is currently applied to PN exposure. A similar conclusion was reached by OEHHA. The implications of this heightened TP vulnerability are greatest for less-than-lifetime exposure and this approach might be used to assess the level of cancer risk from exposures during pregnancy. A case example employing a mutagenic flame retardant was used to exemplify application of a TP ADAF for evaluating risks during pregnancy.

Exposure and risk assessment of volatile organic compounds and airborne phthalates in Singapore's Child Care Centers

Infants and children under 6 years old spend most of daily time in Child Care Centers (CCCs), especially in the tropical regions like Singapore. Environmental exposure and associated risk during this early critical developmental stage is of great public concern. In this study, seven representative volatile organic compounds (VOCs) and five typical phthalates were analyzed in the indoor and outdoor air samples collected from 32 Singapore CCCs. The median of total VOC and phthalate concentration in indoor air was 19.03 and 5.41 μg m−3; respectively. For both indoors and outdoors environment, benzene, toluene and xylene were the dominant VOC contributors (more than 68%). For indoor air phthalates, di(2-ethylhexyl) phthalate and di-butyl phthalate (DBP) accounts for 60–76%. The level of both VOCs and phthalates in indoor environment was significantly higher than that in outdoor, with an average indoor/outdoor ratio of 1.24 and 1.45; respectively. A strong correlation (r > 0.50, p < 0.05) was observed between indoor and outdoor air compounds. VOC and phthalate levels have no significant difference between CCCs with split-unit and centrally ventilated air conditioners. Monte Carlo simulation was used to estimate exposure uncertainty and variability for the risk assessment. Overall, the concentrations of VOC were below the healthy reference values from either EPA Integrated Risk Information System (IRIS) or Singapore guideline. However, similar to other countries’ report, benzene, DBP, ethylbenzene and naphthalene were at levels that could exceed the stringent standards such as Office of Environmental Health Hazard Assessment (OEHHA) cancer and reproductive health-based benchmarks.

Preliminary assessment of lead concentrations in topsoil of 100 parks in Los Angeles, California

Los Angeles has a long history of lead (Pb) contamination due to automobile emissions, industrial processes, and Pb-containing paint. Although the amount of Pb coming from these sources has been reduced or eliminated, exposure to Pb-contaminated soil is still a concern. Contaminated soil in urban parks may constitute an important exposure route, since children are particularly vulnerable to the toxic effects of Pb. While the current EPA clean up level is 400 parts per million (ppm) in recreational and residential areas, the Office of Environmental Health Hazard Assessment (OEHHA) of California revised the soil-screening level to 80 ppm, based on a 1 μg/dL increase of blood level that children experience. In this work, top soil samples in triplicate were taken from each of 100 urban parks in Los Angeles and analyzed to determine Pb concentrations and soil properties. Results show that the average Pb concentration in park soil was 65.5 ppm (range: 0.969–363 ppm), with 35 parks exceeding the California guideline of 80 ppm based on the average Pb concentration measured at each park. Pb concentrations in 42 parks exceeded the background value of 19.7 ppm (by a factor of 3–17). However, variation in measured levels of Pb within most parks was high (>10% RSD in 89 parks). Parks containing elevated Pb concentrations in soil were distributed across many areas of Los Angeles, including central Los Angeles, Beverly Hills, Inglewood, and Central Alameda. Children might potentially suffer from an estimated 1–4 μg/dL increase of blood Pb level according to LeadSpread model. Pb concentrations did not significantly correlate with most soil properties, except for silt (ρ = 0.226, p = 0.012). Additionally, soil from sandy loam contained significantly higher Pb concentrations as compared to soil from loamy sand (p = 0.008). Pb concentrations were significantly correlated with park age (ρ = −0.319, p = 0.033) and were generally lower in areas located away from major roads. Monitoring of parks with high levels of Pb as well as investigation of unexamined regions in Los Angeles are needed.

The impacts of cooking and an assessment of indoor air quality in Colorado passive and tightly constructed homes

Low-energy home design is becoming more common in new and retrofitted homes, and energy-efficient designs often sell at a premium [1]. Efficiency measures, like tightening the building envelope saves energy, but can impact the indoor air quality (IAQ). We monitored the IAQ of nine tightly constructed homes, one tightly constructed public library, and one conventionally constructed home, and performed a repeatable cooking activity to observe the impact of the fine particulate matter (PM2.5) emissions. We compared PM2.5 concentrations from the cooking activity while operating the mechanical ventilation systems at default rates (∼0.1–0.3 h−1) and in a temporary boost mode (∼0.3–0.8 h−1). We also measured the concentrations of total volatile organic compounds (TVOCs), formaldehyde, radon, and bedroom carbon dioxide (CO2) levels. Results show that PM2.5 concentrations were generally low indoors, but cooking drastically increased concentrations, which were slow to decay. No significant difference was found between operating the ventilators at standard rates and utilizing the temporary boost. Completely-mixed flow reactor models of select homes show that installing and using a directly-exhausting range hood reduced peak PM2.5 concentrations by 75% or more. Current ventilation practices in these buildings may not be adequate for these common activities. Formaldehyde was above the California Office of Environmental Health Hazard Assessment (OEHHA) chronic limit of 9 μg/m3 in all tight buildings with a median concentration of 30 μg/m3. CO2 levels in bedrooms exceeded 1000 ppm in six homes, indicating that bedroom ventilation practices were not consistent nor adequate.

Characteristics and health effects of formaldehyde and acetaldehyde in an urban area in Iran

This study reports a spatiotemporal characterization of formaldehyde and acetaldehyde in the summer and winter of 2017 in the urban area of Shiraz, Iran. Sampling was fulfilled according to EPA Method TO-11 A. The inverse distance weighting (IDW) procedure was used for spatial mapping. Monte Carlo simulations were conducted to evaluate carcinogenic and non-cancer risk owing to formaldehyde and acetaldehyde exposure in 11 age groups. The average concentrations of formaldehyde/acetaldehyde in the summer and winter were 15.07/8.40 μg m−3 and 8.57/3.52 μg m−3, respectively. The formaldehyde to acetaldehyde ratios in the summer and winter were 1.80 and 2.43, respectively. The main sources of formaldehyde and acetaldehyde were photochemical generation, vehicular traffic, and biogenic emissions (e.g., coniferous and deciduous trees). The mean inhalation lifetime cancer risk (LTCR) values according to the Integrated Risk Information System (IRIS) for formaldehyde and acetaldehyde in summer and winter ranged between 7.55 × 10−6 and 9.25 × 10−5, which exceed the recommended value by US EPA. The average LTCR according to the Office of Environmental Health Hazard Assessment (OEHHA) for formaldehyde and acetaldehyde in summer and winter were between 4.82 × 10−6 and 2.58 × 10−4, which exceeds recommended values for five different age groups (Birth to <1, 1 to <2, 2 to <3, 3 to <6, and 6 to <11 years). Hazard quotients (HQs) of formaldehyde ranged between 0.04 and 4.18 for both seasons, while the HQs for acetaldehyde were limited between 0.42 and 0.97.

Commuting in Los Angeles: Cancer and Non-cancer Health Risks of Roadway, Light-Rail and Subway Transit Routes

Workers within the megacity of Los Angeles are exposed to significant amounts of airborne particulate matter (PM) during their daily commutes, which often exceed 30–60 minutes each way. Chemical species present in roadway and railway PM, including Benzo[a]pyrene (BaP) and hexavalent chromium (Cr6+), present substantial cancer and non-cancer health risks. In the current study, PM samples were collected and quantitatively speciated along five major commuter routes, including the METRO red line (subway) and gold line (light rail), the I-110 and I-710 freeways, and high-density surface streets (Sunset and Wilshire Boulevards). Using these concentration data, along with cancer potency (CP) and Reference Dosage (RfD) factors obtained from the United States Environmental Protection Agency (USEPA) and California's Office of Environmental Health Hazard Assessment (OEHHA), cancer and non-cancer health risks were calculated. In contrast to previous research indicating that Polycyclic Aromatic Hydrocarbon (PAH) components of Los Angeles roadway PM (e.g., along the I-710 freeway) led to the greatest cancer risk, the current analysis reveals that exposure to carcinogenic transition metals, particularly hexavalent chromium, which are especially prevalent along the METRO red line, results in the greatest cancer and non-cancer health risks. Based on these data, the best option for commuters is to use above-ground light-rail transportation, which allows for reduced exposure to both traffic-generated PAHs and railway-related metals.

Geogenic and Anthropogenic Chromium Contamination in Groundwater in an Ophiolitic Area, Northeastern Iran

Geology of Iran shows an ophiolitic belt around the central Iran micro-continent. One of the main ophiolite suites, with ca. 100km long and 15km wide, located northeastern Iran as Sabzevar ophiolite suite. Ultramafic rocks of this ophiolite suite, display a high concentration of chromium (1000-3000ppm) as a compatible element, especially in pyroxene group minerals. Average Chromium content of this ophiolite suite in peridotites is 2558ppm, with maximum 4525ppm (in pyroxenite) and minimum 832ppm (in dunite). Dunite layers lie underneath of these ultramafic rocks, containing chromite lenses (FeCr2O4) with 20.56wt% Cr2O3. Today, about 10 active mining sites excavate ultramafic rocks for chromite ore mineral and altered ultramafic rocks, serpentinite, dump as unconsolidated gangue materials along stream pathways. There is an unconfined aquifer just southern of this ophiolite range containing detrital altered ultramafic rocks with the high concentration of chromium minerals. In this study 23 groundwater samples, collected from unconfined serpentinite alluvium aquifer that shows cumulative increasing Cr towards south because of increasing residence time, and much more water-rock interactions. Total Cr concentrations in this aquifer are from 12 to 61µg/l, higher than normal level of Cr mentioned by WHO (2µg/l). On the other hand, discharging of chromite mine and mineral processing site, contaminate one of drinking well at Forumad village up to 61µg/l of total chromium. Although trivalent Cr is an essential nutrient, in oxidation conditions with increasing Eh and pH, it changes to chromate (CrO4-2) and dichromate (Cr2O72-) as dissolved anions which will be toxic and carcinogenic in groundwater. Based on California EPA Office of Environmental Health Hazard Assessment (OEHHA), 7.2% of total Cr is hexavalent. Recent information indicates that hexavalent chromium varies from 50% to 90% of the total chromium in many water supplies.

Derivation of an oral Maximum Allowable Dose Level for Bisphenol A

Bisphenol A (BPA) is a high production volume chemical that is used in plastics and epoxy coatings. In 2015, California's Office of Environmental Health Hazard Assessment (OEHHA) added BPA to the Proposition 65 list of chemicals “known to cause reproductive toxicity” based on its Developmental and Reproductive Toxicant Identification Committee's (DART-IC) conclusion that BPA has been shown to cause female reproductive toxicity. A critical factor in determining compliance with Proposition 65 is a Maximum Allowable Dose Level (MADL), which is the exposure level at which a chemical would have no observable reproductive effect even if a person were exposed to 1000 times that level. We performed a comprehensive review of the literature, including the studies reviewed by DART-IC, and derived an oral MADL. Of all the studies we identified, Delclos et al. (2014) is of sufficient quality, has the lowest no observed effect level (NOEL), and results in the most conservative MADL of 157 μg/d. This is generally supported by other studies, including those that were considered by DART-IC. Also, the oral MADL provides a similar margin of safety as OEHHA's dermal MADL and other regulatory guidelines. Taken together, the scientific data support an oral MADL of 157 μg/d.

A Device-Independent Evaluation of Carbonyl Emissions from Heated Electronic Cigarette Solvents.

ObjectivesTo investigate how the two main electronic (e-) cigarette solvents—propylene glycol (PG) and glycerol (GL)—modulate the formation of toxic volatile carbonyl compounds under precisely controlled temperatures in the absence of nicotine and flavor additives.MethodsPG, GL, PG:GL = 1:1 (wt/wt) mixture, and two commercial e-cigarette liquids were vaporized in a stainless steel, tubular reactor in flowing air ranging up to 318°C to simulate e-cigarette vaping. Aerosols were collected and analyzed to quantify the amount of volatile carbonyls produced with each of the five e-liquids.ResultsSignificant amounts of formaldehyde and acetaldehyde were detected at reactor temperatures ≥215°C for both PG and GL. Acrolein was observed only in e-liquids containing GL when reactor temperatures exceeded 270°C. At 318°C, 2.03±0.80 μg of formaldehyde, 2.35±0.87 μg of acetaldehyde, and a trace amount of acetone were generated per milligram of PG; at the same temperature, 21.1±3.80 μg of formaldehyde, 2.40±0.99 μg of acetaldehyde, and 0.80±0.50 μg of acrolein were detected per milligram of GL.ConclusionsWe developed a device-independent test method to investigate carbonyl emissions from different e-cigarette liquids under precisely controlled temperatures. PG and GL were identified to be the main sources of toxic carbonyl compounds from e-cigarette use. GL produced much more formaldehyde than PG. Besides formaldehyde and acetaldehyde, measurable amounts of acrolein were also detected at ≥270°C but only when GL was present in the e-liquid. At 215°C, the estimated daily exposure to formaldehyde from e-cigarettes, exceeded United States Environmental Protection Agency (USEPA) and California Office of Environmental Health Hazard Assessment (OEHHA) acceptable limits, which emphasized the need to further examine the potential cancer and non-cancer health risks associated with e-cigarette use.