Aluminium sulphate

Exposure related observations in humans: other data

Administrative data

Endpoint:

exposure-related observations in humans: other data

Type of information:

other: Incident publication

Adequacy of study:

supporting study

Study period:

No data

Reliability:

other: Exposure related observations

Rationale for reliability incl. deficiencies:

other: Publication underestimated the number of deaths in the exposed area and non¬exposed area, but this would not be large enough to invalidate the conclusions.

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

publication

Title:

Retrospective study of mortality after a water pollution incident at Lowermoor in North Cornwall.

Author:

Owen PJ, Miles DPB, Draper GJ and Vincent TJ.

Year:

2002

Bibliographic source:

BMJ. 324 : 1189.

Materials and methods

Type of study / information:

Retrospective study was conducted to assess the mortality in relation to water pollution incident at Lowermoor in north Cornwall.

Endpoint addressed:

other: mortality

Test guideline

Qualifier:

no guideline followed

Principles of method if other than guideline:

A cohort-retrospective study was conducted to assess the mortality in relation to water contaminated with aluminium sulphate.

GLP compliance:

no

Test material

Test material information

Constituent 1

Reference substance name:

Aluminium sulphate

EC Number:

233-135-0

EC Name:

Aluminium sulphate

Cas Number:

10043-01-3

Molecular formula:

Al.3/2H2O4S

IUPAC Name:

Aluminium sulphate

Test material form:

not specified

Details on test material:

- Name of test material (as cited in study report): Aluminium sulphate

Method

Ethical approval:

not applicable

Details on study design:

Twenty tonnes of aluminium sulphate were inadvertently emptied into the water supply at the Lowermoor treatment works in north Cornwall on 6 July 1988. The maximum recorded aluminium concentration was 620000 µg/L compared with the maximum concentration admissible at the time by the European Community of 200 µg/L (Rowland et al., 1990). Records of deaths in the population whose records were flagged between July 1988 and December 1997 were analysed. Mortality was compared in the area with water pollution (n=11114) with that in an adjacent area free of pollution (n=5359). It was also compared death rates with those in Cornwall and the Isles of Scilly, and England and Wales. Death rates for differences in age distribution and sex was corrected.

Exposure assessment:

estimated

Details on exposure:

TYPE OF EXPOSURE: Accidental exposure

TYPE OF EXPOSURE MEASUREMENT: Mortality

EXPOSURE LEVELS: 20 tonnes (maximum recorded aluminium concentration was 620000 µg/L)

Results and discussion

Results:

- The ratio of the standardised mortality ratios (standardised to England and Wales) for the exposed and unexposed cohorts was 1.08 (95 % confidence interval 0.97 to 1.21); the exposed group had higher mortality, but the excess was not statistically significant. Compared with deaths in Cornwall as a whole, the number of deaths in the exposed group was lower than expected each year: fewer than expected died in the exposed group. The standardised mortality ratio for the exposed population for 1988­97 was 81.6 (77.2 to 86.2), using mortality rates for Cornwall as the standard, and 77.7 (73.5 to 82.0) with England and Wales as standard. For both standards of comparison, significantly fewer people died than expected.
- No statistically significant difference in deaths between the cohort exposed to aluminium sulphate in their water and the non­exposed cohort. The cohort exposed to the pollution had significantly lower mortality than the population of Cornwall and that of England and Wales. This may be because the area has generally low levels of deprivation and historically low death rates.

Any other information on results incl. tables

Table 7.10.5/1: Standardised mortality rates (95% confidence intervals) in groups exposed and unexposed to aluminium sulphate pollution after incident at Lowermoor, North Cornwall

 

Standard	Exposed population (E)	Unexposed population (U)	Ratio (E/U) (95% CI)
England and Wales	77.7 (73.5 to 82.0)	71.8 (65.4 to 78.4)	1.08 (0.97 to1.21)
Cornwall and Isles of Scilly	81.6 (77.2 to 86.2)	75.9 (69.2 to 83.1)	1.07 (0.97 to 1.20)

Applicant's summary and conclusion

Conclusions:

No statistically significant difference in deaths between the cohort exposed to aluminium sulphate in their water and the non­exposed cohort.

Executive summary:

A cohort-retrospective study was conducted to assess the mortality in relation to water contaminated with aluminium sulphate.

 

Twenty tonnes of aluminium sulphate were inadvertently emptied into the water supply at the Lowermoor treatment works in north Cornwall on 6 July 1988.  Records of deaths in the population whose records were flagged between July 1988 and December 1997 were analysed. Mortality was compared in the area with water pollution (n=11114) with that in an adjacent area free of pollution (n=5359). It was also compared death rates with those in Cornwall and the Isles of Scilly, and England and Wales. Death rates for differences in age distribution and sex was corrected.

The ratio of the standardised mortality ratios (standardised to England and Wales) for the exposed and unexposed cohorts was 1.08 (95 % confidence interval 0.97 to 1.21); the exposed group had higher mortality, but the excess was not statistically significant. Compared with deaths in Cornwall as a whole, the number of deaths in the exposed group was lower than expected each year: fewer than expected died in the exposed group. The standardised mortality ratio for the exposed population for 1988­97 was 81.6 (77.2 to 86.2), using mortality rates for Cornwall as the standard, and 77.7 (73.5 to 82.0) with England and Wales as standard. For both standards of comparison, significantly fewer people died than expected. No statistically significant difference in deaths between the cohort exposed to aluminium sulphate in their water and the non­exposed cohort. The cohort exposed to the pollution had significantly lower mortality than the population of Cornwall and that of England and Wales. This may be because the area has generally low levels of deprivation and historically low death rates.