Table 2.

Incidence rate (IR) of LRTI by prenatal exposure to p,p′-DDE and p,p′-DDT among boys from Tapachula, Chiapas, Mexico 2002–2005

Organochlorines (μg/g lipids)	n	% with LRTIa	Episodes of LRTI	Child-yearb	IR per child- year
Overall	747	18.6	267	1387	0.19
p,p′-DDEc
≤ 3.00	400	19.3	164	732	0.22
3.01 – 6.00	166	16.9	46	309	0.15
6.01 – 9.00	68	20.6	23	129	0.18
> 9.00	113	17.7	34	218	0.16
p,p′-DDTc
≤ 0.25	362	21.6	157	664	0.24
0.26 – 0.75	196	15.8	62	366	0.17
0.76 – 1.99	104	16.4	25	193	0.13
≥ 2.00	85	15.3	23	164	0.14

LRTI, lower respiratory tract infections

^aPercentage of children with at least one episode of LRTI during FU

^bThe person-time for each child was calculated as the date of birth to the first visit and as the time since the previous visit (when the child had two or more visits)

^cCategorized using the same cut points applied in previous analyses of these data (Cupul-Uicab et al., 2008; Longnecker et al., 2007)