However, the studies were cross-sectional and reported on results in workers who, for the most part, were currently exposed to carbaryl, so it is unclear whether the response would persist after cessation of exposure. Two studies found altered hormonal status in individuals with pesticide exposure, but the clinical significance of the findings and whether they persist after exposure were not determined.

Only one of the TTP studies provided an analysis of specific insecticide use (Curtis et al., 1999) (Table 8.2). It did not show delayed TTP for either maternal or paternal exposure, although there was a suggestion of delayed time to conception for women who used organophosphates and carbaryl. Other studies considered pesticide exposures that were too broad for the purposes of this review.

The committee concludes, from its assessment of the epidemiologic literature, that there is inadequate/insufficient evidence to determine whether an association exists between exposure to the insecticides under review and male or female infertility after cessation of exposure.

TABLE 8.1 Selected Epidemiologic Studies: Sperm and Semen Parameters and Exposure to Carbaryl

Reference

Population

N

Results (% with Oligospermia or teratospermia)

Whorton et al., 1979

Carbaryl production workers

 

Oligospermia

 

 

Carbaryl workers

47

14.9a

 

Current carbaryl workers

29

17.2

 

Previous carbaryl workers

18

11.1

 

Chemical-worker controls

90

5.5a

Wyrobek et al., 1981

Carbaryl production workers

 

Oligospermia

 

 

Carbaryl workers

48

14.6

 

New-hire controls

34

5.9

 

Teratospermia

 

 

Carbaryl workers

49

28.6

 

New-hire controls

34

11.8

aThe comparison of carbaryl workers with controls resulted in p value of 0.07. No further comparisons were presented.

TABLE 8.2 Selected Epidemiologic Studies: Time-to-Pregnancy and Exposure to Insecticides

Reference

Population

Number of Exposure Intervalsa

Fecundability Ratio (95% CI)

Curtis et al., 1999

Ontario farm couples

 

 

Insecticides

 

 

Females

111

1.02 (0.76–1.37)

 

Males

744

1.01 (0.87–1.17)

 

Organophosphates

 

 

Females

89

0.75 (0.51–1.10)

 

Males

391

1.04 (0.89–1.22)

 

Carbaryl

 

 

Females

51

0.97 (0.63–1.49)

 

Males

214

1.03 (0.84–1.26)

aNumber of 3-month exposure windows in which the man or woman reported pesticide use.



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