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Persistent Organic Pollutants Used for Industrial Purposes: Origins in the Environment
Published in Narendra Kumar, Vertika Shukla, Persistent Organic Pollutants in the Environment, 2021
Brenda Natalia López Niño, Michal Jeremiáš
Human dietary exposure has been calculated based on individual body weight and contaminant concentrations in collected diet samples; the results are compared to the respective reference doses. A reference dose is the maximum acceptable oral dose of a toxic substance. In a Norwegian cohort, the median and 95th percentile dietary exposures did not exceed the reference dose, except for PCBs. The participants were exposed to higher levels of the novel FR 2-ethylhexyl phenyl phosphate than other FRs (Xu et al., 2017). Another dietary exposure assessment is made according to acute, or short-term, dietary exposure estimates for chemical residues. It is based on food consumption data at the 97.5th percentile for consumers of the food. From the study of 120 retail food and 19 diet study samples in the UK, the estimated human exposure dietary intake was low. The levels in the samples examined do not suggest a cause for concern. But the occurrence of POPs was observed in food imported from countries where they are produced and used; therefore, the movement of food traded between countries should be controlled (Fernandes et al., 2019).
Laws, Regulations, and Risk Assessment Relevant to Site Assessment and Remediation
Published in Cristiane Q. Surbeck, Jeff Kuo, Site Assessment and Remediation for Environmental Engineers, 2021
Cristiane Q. Surbeck, Jeff Kuo
The reference dose (RfD) is defined as an estimate of a daily oral exposure to the human population (including the sensitive receptors) that is likely to be without an appreciable risk of harmful effects during a lifetime. It is often derived from NOAEL or LOAEL with order-of-magnitude uncertainty factors (UFs) or safety factors. It is generally expressed in units of milligrams per kilogram of body weight per day (mg/kg/day). A similar term, known as reference concentration (RfC), is used to assess inhalation risks, where concentration refers to levels in the air (generally expressed in units of milligrams of the chemical agent per cubic meter of air, mg/m3). For noncancer health effects, risk from exposure to a specific quantity is expressed as a Hazard Index (HI), which is the average daily dose (ADD) divided by RfD: Hazard Index HI=Average Daily Dose ADD÷RfD
Risk Assessment Based on Data from the Toxic Chemical Release Inventory
Published in Rhoda G.M. Wang, Water Contamination and Health, 2020
Andrew Battin, Nancy Chiu, James Darr
EPA expresses potency for toxicological effects other than cancer as a reference dose (RfD). The reference dose is defined as “an estimate (with uncertainty spanning perhaps an order of magnitude) of a daily exposure to the human population (including sensitive subgroups) that is likely to be without appreciable risk of deleterious effects during a lifetime” and is expressed as a mg/kg/day dose. The RfD is usually based on the most sensitive known effect. Although some RfD are based on actual human data, RfD are most often calculated from results obtained in oral chronic or subchronic animal studies. EPA calculates a comparable measure of potency for inhalation exposures, called a reference concentration (RfC). At the time of the screening exercise, very few RfC values were available so we typically used the corresponding RfD value as a rough indicator of inhalation toxicity. In making these judgments, we took into account considerations of metabolism and pharmacokinetics in judging whether the oral RfD was a valid indicator for the inhalation toxicity of the subject chemical. Of the four chemicals discussed in this chapter, the only RfD/ RfC value available at the time of the screening was an RfD for N,N-dimethylaniline.
Risk assessment of population exposure to toxic trace elements via consumption of vegetables and fruits grown in some mining areas of Armenia
Published in Human and Ecological Risk Assessment: An International Journal, 2018
Davit Pipoyan, Meline Beglaryan, Lara Costantini, Romina Molinari, Nicolò Merendino
Oral reference dose is an estimation of maximum permissible risk to human population through daily exposure when taking into consideration a sensitive group during a lifetime. The applied RfD for Mo, Ni, Zn, As, and Cd were 0.005, 0.02, 0.3, 0.0003, and 0.001 mg/kg/BW/day, respectively (US EPA 1989, 1991a, 1991b, 1992, 2005; Giri 2017). Taking into consideration tolerable daily intake (TDI) proposed by EFSA (EFSA 2014), the oral reference dose for Cr(III) was 0.3 mg/kg/BW/day. Taking into consideration provisional tolerable weekly intake (EFSA 2010), the oral reference dose for Pb was 0.0035 mg/kg/BW/day. For Hg the tolerable weekly intake (0.004 mg/kg/BW/day) was considered (EFSA 2012). Dietary reference intake (0.01 mg/kg/BW/day) was used as a reference dose for Cu (ATSDR 2004).
Evaluation of groundwater contamination for fluoride and nitrate in semi-arid region of Nirmal Province, South India: A special emphasis on human health risk assessment (HHRA)
Published in Human and Ecological Risk Assessment: An International Journal, 2019
Narsimha Adimalla, Peiyue Li, Hui Qian
The reference dose is used as a measure of non-carcinogenic chronic hazards. Toxic effects are likely to ensue, when the exposure dose of the target contaminant exceeds the reference dose, which is generally articulated as hazard quotient (HQ):where RfD signifies the reference dose for chronic oral exposure/non-carcinogenic risk, which is 6E-2 and 1.6E+0 mg/kg/day for F− and NO3−, respectively (USEPA 2014). However, the total hazard index (THI) of non-carcinogenic risk is computed by Eq. 4:
Investigations of the chemical distribution of heavy metals in street dust and its impact on risk assessment for human health, case study of Radom (Poland)
Published in Human and Ecological Risk Assessment: An International Journal, 2020
Marzena Trojanowska, Ryszard Świetlik
The reference dose (mg kg−1day−1) was an estimate of the maximum permissible risk to a human population through a daily exposure during a lifetime. The values of RfD for all metals are shown in Table S3 (SI).