Table 4.
RRs (95% CIs) for external causes of mortality by lifetime chlorpyrifos exposure-days among Agricultural Health Study applicators stratified by state of residence and farm type, 1993–2001.
| External causes of mortality (V01–Y98)
|
Suicide (X60–X84)
|
Non-motor-vehicle accidents (W00–X59)
|
||||
|---|---|---|---|---|---|---|
| Stratification variable, chlorpyrifos exposure | No. of deathsa | RRb (95% CI) | No. of deaths | RR (95% CI) | No. of deaths | RR (95% CI) |
| State of residence | ||||||
| Iowa | ||||||
| Nonexposed | 68 | 1.0 (referent) | 12 | 1.0 (referent) | 25 | 1.0 (referent) |
| ≤ 20.0 | 17 | 0.93 (0.53–1.65) | 4 | 1.41 (0.43–4.57) | 8 | 0.88 (0.48–1.63) |
| 20.1–56.0 | 18 | 1.15 (0.66–2.00) | 3 | 1.21 (0.33–4.47) | 7 | 1.08 (0.58–2.00) |
| ≥ 56.1 | 22 | 2.36 (1.41–3.95) | 6 | 3.93 (1.41–10.96) | 8 | 1.95 (1.06–3.58) |
| ptrend | 0.001 | 0.008 | 0.023 | |||
| North Carolina | ||||||
| Nonexposed | 73 | 1.0 (referent) | 20 | 1.0 (referent) | 20 | 1.0 (referent) |
| ≤ 20.0 | 10 | 0.53 (0.24–1.17) | 5 | 1.04 (0.34–3.21) | 0 | — |
| 20.1–56.0 | 10 | 0.56 (0.23–1.33) | 2 | 0.85 (0.19–3.87) | 2 | 0.31 (0.07–1.34) |
| ≥ 56.1 | 10 | 0.93 (0.42–2.02) | 3 | 0.93 (0.19–4.57) | 6 | 2.14 (1.00–4.60) |
| ptrend | 0.966 | 0.921 | 0.007 | |||
| Farm typec | ||||||
| Crop | ||||||
| Nonexposed | 56 | 1.0 (referent) | 15 | 1.0 (referent) | 11 | 1.0 (referent) |
| ≤ 20.0 | 9 | 0.60 (0.25–1.43) | 2 | 0.43 (0.05–3.34) | 3 | 1.28 (0.49–3.34) |
| 20.1–56.0 | 9 | 0.87 (0.38–1.98) | 1 | 0.63 (0.08–5.03) | 2 | 0.50 (0.11–2.19) |
| ≥ 56.1 | 12 | 1.57 (0.78–3.24) | 4 | 1.95 (0.50–7.58) | 7 | 4.36 (2.00–9.53) |
| ptrend | 0.155 | 0.268 | 0.001 | |||
| Animal | ||||||
| Nonexposed | 75 | 1.0 (referent) | 14 | 1.0 (referent) | 29 | 1.0 (referent) |
| ≤ 20.0 | 15 | 0.70 (0.39–1.26) | 6 | 1.62 (0.58–4.52) | 4 | 0.34 (0.14–0.80) |
| 20.1–56.0 | 17 | 0.82 (0.45–1.49) | 3 | 1.10 (0.30–4.06) | 7 | 0.94 (0.51–1.74) |
| ≥ 56.1 | 20 | 1.79 (1.05–3.06) | 5 | 2.96 (0.96–9.07) | 7 | 1.49 (0.80–2.81) |
| ptrend | 0.016 | 0.072 | 0.095 | |||
| Farm size (acres) | ||||||
| < 500 | ||||||
| Nonexposed | 89 | 1.0 (referent) | 18 | 1.0 (referent) | 31 | 1.0 (referent) |
| ≤ 20.0 | 16 | 0.56 (0.30–1.04) | 5 | 1.02 (0.33–3.17) | 4 | 0.35 (0.15–0.82) |
| 20.1–56.0 | 15 | 0.68 (0.34–1.33) | 2 | 0.85 (0.19–3.83) | 4 | 0.58 (0.25–1.37) |
| ≥ 56.1 | 13 | 1.32 (0.70–2.50) | 3 | 1.52 (0.33–6.97) | 6 | 1.99 (1.03–3.83) |
| ptrend | 0.768 | 0.786 | 0.640 | |||
| ≥ 500 | ||||||
| Nonexposed | 27 | 1.0 (referent) | 6 | 1.0 (referent) | 8 | 1.0 (referent) |
| ≤ 20.0 | 9 | 1.25 (0.56–2.78) | 3 | 1.54 (0.36–6.58) | 4 | 1.43 (0.58–3.51) |
| 20.1–56.0 | 10 | 1.30 (0.60–2.82) | 2 | 1.06 (0.21–5.42) | 4 | 1.17 (0.47–2.90) |
| ≥ 56.1 | 18 | 3.00 (1.52–5.92) | 5 | 3.30 (0.92–11.78) | 8 | 3.14 (1.43–6.89) |
| ptrend | 0.004 | 0.121 | 0.012 | |||
The reduced number of subjects included in the intensity-weighted exposure-days analysis is attributed to occasional missing data for some components of the intensity algorithm.
Relative risks adjusted for age at enrollment, sex, education, smoking, frequency of alcohol drinking during the 12 months before enrollment, and state of residence, and the four pesticides most highly correlated with chlorpyrifos (alachlor, carbofuran, fonofos, trifluralin). The reference category was applicators who were not exposed to chlorpyrifos. Applicators who did not provide information on chlorpyrifos days used per year, years of use, and intensity level were excluded from this analysis.
The variable was generated using the information on beef cattle, dairy cattle, hogs/swine, poultry, sheep, eggs, other farm animals, and type of crop in the enrollment questionnaire. The categories are not mutually exclusive.