Table 1.  Adult Exposure Factors Recommended by NAFTA (USEPA, Health
Canada, and California DPR).

Scenario	

NAFTA Recommendations







Gender Specific

	

Comments

	

Males	

Females	

Males & Females

	

Body Weight (kg)

	

76.9 (round to 77)	

62.4 (round to 62)	

69.7 (round to 70)	

Median values (USEPA, 1997).  Value for Males & Females represents the
average of the median body weights for males and females (USEPA, 1997). 
NAFTA recommends using data for either sex or the average of both sexes,
depending on whether sex was specified in the study.  If both males and
females were included in a study the male/female average should be used.
 Note: USEPA may use 71.8 kg (males and females) once the Exposure
Factors Handbook is finalized.  However, since the median value for
surface area has been selected, the median body weight should also be
used.



Surface Area (cm2)	

	

	

	

Surface areas for individual body parts represent median values from
USEPA (1997).  Male upper arms represent the value for arms minus the
value for forearms.  Female upper arms and forearms are based on the
data for arms, assuming the same ratio of upper arms to forearms as for
males.  Totals represent the sum of the median values for individual
parts.  Although it is not entirely correct to sum percentile values, it
allows for consistency between the individual body parts data and the
totals.  Another appropriate method might be to use the median total
surface areas, and the percentages of each body part to estimate surface
areas for each part.  This would also ensure consistency with total
surface area.  Values for males and females combined were calculated by
averaging the data sets for the two groups.  NAFTA recommends using the
median values for either sex or the average of both sexes, depending on
whether sex was specified in the study.  If both males and females were
included in a study the male/female average should be used.  The body
surface areas in PHED V2.0 will be switched to the male surface area. 
Although USEPA (1997) recommends using the mean surface areas, it also
states that the median values maybe used “when surface area
distributions are preferred”.



Head	

1,300	

1,110	

1,205

	

Trunk (including neck)	

7,390	

5,790	

6,590

	

Arms	

-	

-	

-

	

Upper Arms	

1,600	

1,265	

1,433

	

Forearms	

1,310	

1,035	

1,173

	

Hands	

990	

817	

904

	

Thighs	

3,820	

3,260	

3,540

	

Lower Legs	

2,560	

2,180	

2,370

	

Feet	

1,310	

1,140	

1,225

	

Total	

20,280	

16,597	

18,440

	

Life Expectancy (years)	

72.1	

78.9	

75	

Average values, based on 1993 projections (USEPA, 1997).  It should be
noted, however, the expectation of life at birth has averaged above 70
years since before 1970, and has been approximately 75 years since 1982.
 These individuals are now almost 16 years old and could represent
members of the agricultural work force. NAFTA (and USEPA 1997)
recommends using 75 years for adults, except in situations where gender
is a factor.



Working Lifetime (years)	

-	

-	

40	

Based on data in USEPA (1997) from Carey (1988) for the occupational
group "farming, forestry, and fishing" that indicates a  median tenure
of 39.8 years for the 65+ age group.  NAFTA recommends using 40 years
for agriculture, but not necessarily for antimicrobial uses.  For the
antimicrobial uses it is recommended that specific values from the
Exposure Factors Handbook be used for various industries.  USEPA (1997)
allows occupational specific values such as the one selected by NAFTA.



Chronic Inhalation Rates (m3/day)	

15.2	

11.3	

13.3	

Based on the averages of Layton's (1993) three approaches for
calculating inhalation rates (i.e., using average daily food energy
equivalents, basal metabolic rates, and energy expenditure based on
activity level), as presented in USEPA (1997).  A value for males and
females combined is not provided in USEPA (1997), but is recommended by
NAFTA by estimating the average of the male and females values (i.e.,
13.3 m3/day).



Short- and intermediate-term Inhalation Rates (m3/hr)	

	

	

	

Based on the average of several studies (Adams, 1993; Layton, 1993; Linn
et al., 1992) presented in USEPA (1997).  NAFTA discussed reporting
values for male and female, however, several methods were used to
calculate the combined male and female values (e.g., age groups, time
activity, and basal metabolic rates).  Recalculating the male and female
values separately is out of the scope of this project.  If gender
specific values are needed, NAFTA recommends using the values reported
by Layton in USEPA (1997).

The activities correspond to the following:  

Rest -lying down,

Sedentary - sitting, pilot, driving a tractor,

Light - flagger, mixer/loader (containers < 50 lb), pneumatic reel
sprayer, lawn treatment, most harvesters,

Moderate - mixer/loader (containers > 50 lb), backpack sprayer
(greenhouse, hilly conditions, heavy brush), harvesters using ladders,

Heavy - generally not applicable to occupational exposure to pesticides.





Rest	

-	

-	

0.4

	

Sedentary Activity	

-	

-	

0.5

	

Light Activity	

-	

-	

1.0

	

Moderate Activity	

-	

-	

1.6

	

Heavy Activity	

-	

-	

3.2

	Table 2.   Child Exposure Factors Recommended by NAFTA (USEPA, Health
Canada, and California DPR).

Scenario	

NAFTA Recommendations

	

Gender Specific	

Comments

	

Males	

Females	

Males & Females

	

Body Weight (kg)	

	

	

	

Mean values (USEPA, 1997), and median values in parentheses.  The value
for Males & Females represents the average of the median body weights
for males and females.  Mean values for males & females are not 
reported, but these values can be calculated by averaging the mean  male
and female values for each age group.

NAFTA recommends using the median values (reported in parentheses)  to
be consistent with the use of the median surface areas. 



6-11 months	

9.4 (9.4)	

8.8 (8.9)	

(9.2)

	

1 year	

11.8 (11.7)	

10.8 (10.7)	

(11.2)

	

2 years	

13.6 (13.5)	

13.0 (12.7)	

(13.1)

	

3 years	

15.7 (15.4)	

14.9 (14.7)	

(15.1)

	

4 years	

17.8 (17.6)	

17.0 (16.7)	

(17.2)

	

5 years	

19.8 (19.4)	

19.6 (19.0)	

(19.2)

	

6 years	

23.0 (22.0)	

22.1 (21.3)	

(21.7)

	

7 years	

25.1 (24.8)	

24.7 (23.8)	

(24.3)

	

8 years	

28.2 (27.5)	

27.9 (27.5)	

(27.5)

	

9 years	

31.1 (30.2)	

31.9 (29.7)	

(30.0)

	

10 years	

36.4 (34.8)	

36.1 (34.5)	

(34.7)

	

11 years	

40.3 (37.3)	

41.8 (40.3)	

(38.8)

	

12 years	

44.2 (42.5)	

46.4 (45.4)	

(44.0)

	

13 years	

49.9 (48.4)	

50.9 (49.0)	

(48.7)

	

14 years	

57.1 (56.4)	

54.8 (53.1)	

(54.8)

	

15 years	

61.0 (60.1)	

55.1 (53.3)	

(56.7)

	

16 years	

67.0 (64.4)	

58.1 (55.6)	

(60.0)

	

17 years	

66.7 (65.8)



59.6 (58.4)



(62.1)





18 years	

71.1 (70.4)



59.0 (56.4)



(63.4)





Total Surface Area (cm2)	













Surface areas for individual age groups represent the recommended median
values from USEPA (1997), except for the <1 and 1 < 2 year age groups
which were taken from ICRP (1981).  NAFTA recommends using the male and
female combined values that are based on the average of the median  male
and female data, unless gender specific data are warranted.  



< 1 year	

-



-



3925





1 < 2 years	

-



-



5275





2 < 3 years	

6030



5790



5910





3 < 4 years	

6640



6490



6565





4 < 5 years	

7310



7060



7185





5 < 6 years	

7930



7790



7860





6 < 7 years	

8660



8430



8545





7 < 8 years	

9360



9170



9265





8 < 9 years	

10000



10000



10000





9 < 10 years	

10700



10600



10650





10 < 11 years	

11800



11700



11750





11 < 12 years	

12300



13000



12650





12 < 13 years	

13400



14000



13700





13 < 14 years	

14700



14800



14750





14 < 15 years	

16100



15500



15800





15 < 16 years	

17000



15700



16350





16 < 17 years	

17600



16000



16800





17 < 18 years	

18000



16300



17150





Percentage of Surface Area of Body Parts (%)	

head	

trunk	

arms	

hands	

legs	

feet	

Based on mean percentages for males and females  combined from USEPA 
(1997).  Values with *'s estimated using regression analyses.



< 1 year	

18.2	

35.7	

13.7	

5.3	

20.6	

6.54

	

1 < 2 years	

16.5	

35.5	

13	

5.68	

23.1	

6.27

	

2 < 3 years	

14.2	

38.5	

11.8	

5.3	

23.2	

7.07

	

3 < 4 years	

13.6	

31.9	

14.4	

6.07	

26.8	

7.21

	

4 < 5 years	

13.8	

31.5	

14	

5.7	

27.8	

7.29

	

5 < 6 years	

13.5*	

34.7*	

13.4*	

5.46*	

26.0*	

7.04*

	

6 < 7 years	

13.1	

35.1	

13.1	

4.71	

27.1	

6.9

	

7 < 8 years	

12.3*	

34.4*	

13.5*	

5.44*	

27.3*	

7.13*

	

8 < 9 years	

11.7*	

34.2*	

13.6*	

5.43*	

27.9*	

7.17*

	

9 < 10 years	

12	

34.2	

12.3	

5.3	

28.7	

7.58

	

10 < 11 years	

10.7*	

33.8*	

13.7*	

5.39*	

29.2*	

7.24*

	

11 < 12 years	

10.2*	

33.6*	

13.8*	

5.38*	

29.8*	

7.27*

	

12 < 13 years	

8.74	

34.7	

13.7	

5.39	

30.5	

7.03

	

13 < 14 years	

9.97	

32.7	

12.1	

5.11	

32	

8.02

	

14 < 15 years	

8.81*	

32.9*	

13.9*	

5.31*	

31.7*	

7.35*

	

15 < 16 years	

8.39*	

32.7*	

14.0*	

5.27*	

32.3*	

7.37*

	

16 < 17 years	

7.96	

32.7	

13.1	

5.68	

33.6	

6.93

	

17 < 18 years	

7.58	

31.7	

17.5	

5.13	

30.8	

7.28

	

Chronic Inhalation Rates (m3/day)	













Specific Ages:  Based on the data from Layton (1993) and presented in
USEPA (1997) that uses energy intakes to estimate inhalation rates.The
Male & Female combined values for the 9-11, 12-14, and 15-18 age groups
were calculated from the values reported in USEPA (1997). 



< 1 year	

-



-



4.5





1-2 years	

-



-



6.8





3-5 years	

-



-



8.3





6-8 years	

-



-



10





9-11 years	

14



13



13.5





12-14 years	

15



12



13.5





15-18 years	

17



12



14.5





Short- and intermediate-term Inhalation Rates (m3/hr)	

6 years old



-



-



Based on the mean from two reports (Astrand, 1952; Robinson, 1938) 
presented in USEPA (1985) and USEPA (1997). The ratios of ventilation
rate and BW are highest for 6-year old male children. The ratios for
6-year old female children are not available.





Rest	

0.4



-



-





Light Active	

0.8



-



-





Moderate Active	

2.0



-



-





Heavy Active 	

2.3



-



-





REFERENCES:

Adams, W.C. (1993) Measurement of breathing rate and volume in routinely
performed daily activities, Final Report.  California Air Resources
Board (CARB).  Contract No. A033-205.

Astrand, P.O. (1952) Experimental studies of physical working capacity
in relation to sex and age. Ejnar Munksgaard, copenhagen, Danmark.

Carey, M. (1988) Occupational tenure in 1987: many workers have remained
in their fields.  Monthly Labor Review.  October 1988. 3-12.

ICRP (1981) International Commission on Radiological Protection.  Report
of the task group on reference man.  Pergammon Press, New York.

Layton (1993) Metabolically consistent breathing rates for use in dose
assessments.  Health Physics.  64(1) 23-36.

Linn, W.S., Spier, C.E., Hackney, J.D. (1992) Documentation of activity
patterns in "high risk" groups exposed to ozone in the Los Angeles area.
 In proceedings of the Second Annual EPA/AWMA Conference on Tropospheric
Ozone. Atlanta, November 1991. Air Waste Management Association,
Pittsburgh, PA.

Robinson, S. (1938) Experimental studies of physical fitness in relation
to age. Arbeitephysiologie. 10:251-323.

USEPA (1985) Development of Statistical Distributions or Ranges of
Standard Factors Used in Exposure Assessments. Office of Health and
Environmental Assessment, Office of Research and Development, U.S.
Environmental Protection Agency.

USEPA (1997)  Exposure Factors Handbook, 1997.  Office of Research and
Development, U.S. Environmental Protection Agency. 
EPA/600/P-95/002Fa,c.

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