Epidemiological study (observational study)

Childhood cancer in relation to a modified residential wire code epidem.

By: Savitz DA, Kaune WT

Published in: Environ Health Perspect 1993; 101 (1): 76-80

Aim of study (acc. to author)

The data of a case-control study on childhood cancer in the Denver metropolitan area, USA, were reanalyzed by use of a modified Wertheimer-Leeper scheme.

Further details

The Wertheimer-Leeper scheme comprises 5 categories: buried, very low current configuration (VLCC), ordinary low current configuration (OLCC), ordinary high current configuration (OHCC), and very high current configuration (VHCC). These categories were dichtomized as low (buried, very low, and ordinary low) and high (ordinary high and very high) wire codes. The modified wire codes analyzed in the present study were derived based on their relations with measured fields. The three categories of the modified wire code are high wire code (HWC, homes within 20 m of a transmission or three-phase primary line), medium wire code (MWC, homes that are not HWC but have a transmission line or three-phase primary line within 46 m or an open secondary line within 26 m), and low wire code (LWC).

Endpoint/type of risk estimation

childhood leukemia: leukemia, acute lymphoblastic leukemia
childhood lymphoma
childhood brain/CNS tumor
other childhood cancer: soft tissue sarcoma, and other types
all childhood cancer

Type of risk estimation:

incidence

(odds ratio (OR))

Exposure

Assessment

wire code: Wertheimer-Leeper scheme and modified Wertheimer-Leeper scheme

Exposure groups

Group	Description
Reference group 1	Wertheimer-Leeper scheme, wire code: buried wire
Group 2	Wertheimer-Leeper scheme, wire code: very low current
Group 3	Wertheimer-Leeper scheme, wire code: ordinary low current
Group 4	Wertheimer-Leeper scheme, wire code: ordinary high current
Group 5	Wertheimer-Leeper scheme, wire code: very high current
Reference group 6	wire code: low
Group 7	wire code: high
Reference group 8	modified wire code: low (LWC)
Group 9	modified wire code: medium (MWC)
Group 10	modified wire code: high (HWC)

Population

Group:
- children
Age: 0–14 years
Observation period: 1976 - 1983
Study location: USA (Denver area)

Case group

Characteristics: childhood cancer
Data source: Colorado Central Cancer Registry

Control group

Selection:
- random-digit dialing of telephone number
Matching:
- sex
- age
- area

Study size

	Cases	Controls
Eligible	356	378
Participants	252	222

Statistical analysis method:

logistic regression
Mantel-Haenszel method

(adjustment:

age
race, mother's smoking, per capita income, year of diagnosis, and residential stability

)

Results (acc. to author)

The modified wire code generated risk estimates that were precise elevated for the high wire code compared to low wire code classifications. The odds ratios for childhood cancer, leukemia, and brain cancer were significantly elevated. Potential confounding was examined and generally found to be absent.
The reanalysis of the data on childhood cancer and wire configuration codes showed a stronger relationship for the modified wire codes as to the original Wertheimer-Leeper scheme.

Limitations (acc. to author)

Selection bias due to different participation of controls in the study cannot be ruled out.

Study funded by

Department of Energy, USA

Comments on this article

Jones TL (1993): Magnetic fields and cancer

Kaune WT et al. (1994): Simplification of the Wertheimer-Leeper wire code
Feychting M et al. (1993): Magnetic fields and cancer in children residing near Swedish high-voltage power lines
London SJ et al. (1991): Exposure to residential electric and magnetic fields and risk of childhood leukemia
Savitz DA et al. (1988): Case-control study of childhood cancer and exposure to 60-Hz magnetic fields
Tomenius L (1986): 50-Hz electromagnetic environment and the incidence of childhood tumors in Stockholm County
Wertheimer N et al. (1979): Electrical wiring configurations and childhood cancer