sand/gravel Playing on grass 1 hrs/d Playing on dirt 0.8 hrs/d Time spent swimming 23 hr/year Average value. Upper estimate not available (Section 6.2.4.3) See Footnote (a) to Table E1. For screening risk assessments and establishing guidelines the most sensitive receptor is assumed to be a 2–3 year old (Table E5) or a 1–2 year old (Table E6). Table E6: Summary of suggested exposure factors for 1–2 year old child (male and female combined). Values are average or 95th percentile (in parenthesis) Parameter Suggested default Units Comment and internal reference Anatomical and physiological parameters Body weight (13) kg Section 2.2.4 Body height 81 (86) cm Section 2.1.4 Dermal exposure parameters Total skin surface area 5,300 (6,100) cm2 Section 3.2.4. See Table 3.2.5 for specific body part data. Exposed skin surface area 1,600 (1,900) cm2 Section 3.2.3, 3.2.4 Oral exposure parameters Drinking water intake 0.3 (0.9) L Tap water intake. Includes water used in food preparation (Section 4.2.3). Food intake (excludes beverages except for milk) 720 (1,700) g/day For intakes of individual food groups, see section 4.4.4. Soil ingestion 50, (100), [100] mg/day Central tendency for outside soil. (Reasonable maximum, outside soil), [Central tendency outside soil + indoor dust]. (Section 4.5.3) Incidental water ingestion while swimming 50 (~ average) 150 (~ upper estimate) mL/hr Section 4.6.3 Inhalation exposure parameters Inhalation rate 8.0 (12.8) m3/day Section 5.1.3. For specific inhalation rates by activity or for short term exposures, see Section 5.1;Table 5.1.2
Table 5.1.3: ICRP average reference values for daily ventilation rates Life stage Ventilation rate (m3/day) Children 3 months 2.8 1 year 5.1 5 years 8.8 10 years 15.2 15 year old females 15.8 15 year old males 20.1 Adults Female 18.2 Male 22.2 Data from ICRP 2002, p. 26 Workers The ICRP (2002, p. 27) also provide reference ventilation rates for workers according to the level of work performed. Table 5.1.4 provides the ICRP reference values for sedentary male and female workers, and males conducting heavy work like firemen, construction workers and farm workers. Information for female workers performing heavy duties was not available. Recommendations The ICRP (1975, 2002) recommendation for the average inhalation rate for adults (male and female combined) in the general population is 20 m3/day (from Table 5.1.3). The US EPA IRIS (1995; 2002; 2003; 2009) also uses a default inhalation rate of 20 m3/day for its calculations. The WHO also applies the 20 m3/day inhalation rate in some of its assessments (e.g. WHO CICAD 2006). In 1994 Health Canada (CEPA 1994) recommended an average value of 23m3/d for use in risk assessments for priority substances (for adults). However, for federal contaminated site risk assessment, the Canadian 2004 guidance on preliminary quantitative risk assessment indicates an average of 15.8 m3/d is appropriate (Health Canada 2004). It is noted these different recommendations are supported by different source documents; the higher inhalation rate was taken from a survey of Canadians undertaken in 1992, the lower value is supported by a probabilistic assessment of a large number of studies cited in Allan and Richardson (1998) and is likely to be more representative of the overall Canadian adult population. The lower value is similar to the average inhalation rate for adults (average for 16–<81 years old is 15 m3/d) recommended by the US EPA (2009b, Table 5.1.1), the US EPA recommendation is supported by a diferent set of studies to the Canadian recommendation.