Developments in reproductive risk management

Risk of congenital anomalies in children of parents occupationally exposed to low level ionising radiation

OBJECTIVES

To evaluate the risk of having a child with a congenital anomaly in relation to occupational exposure to low level ionising radiation in the pre-conception period.

METHODS

A case-control study based on the Canadian congenital anomalies registry used record linkage techniques to identify congenital anomalies among male and female workers in Canada's largest electric company. Cases were defined as parents of a child with a congenital anomaly born between April 1979 and December 1986 who had a congenital anomaly diagnosed within the first year of life. Controls were an individually matched sample of parents of a liveborn child without an anomaly. Risk of congenital anomaly was assessed in relation to parental exposure to ionising radiation acquired through work within a nuclear generating station of an electric power company. Exposure was assessed according to employment, whether or not the worker was monitored for radiation exposure, and quantitative estimates of radiation dose.

RESULTS

Employment within the electric power industry was not associated with an increased risk of congenital anomalies in the offspring of mothers or fathers. Risk estimates for workers monitored (those who are likely to be exposed to ionising radiation) were 1.75 (95% confidence interval (95% CI) 0.86 to 3.55) for mothers and 0.84 (95% CI 0.68 to 1.05) for fathers. Exposure for fathers before conception, defined cumulatively and for six months before conception, was not associated with increased risk of anomalies in their offspring. There were no significant increases in risk found between type of anomaly and any measure of exposure, although the statistical power in these groups was limited. The study had insufficient numbers to evaluate the effects of ionising radiation in mothers as only three mothers had recorded doses > 0 mSv.

CONCLUSIONS

Overall, workers in a nuclear power industry, and specifically those exposed before conception to low levels of ionising radiation, do not appear to be at an increased risk of having a liveborn child with a congenital anomaly.

Assessment of Reproductive Risk at Work

The risk-assessment process involves hazard identification, dose&endash;response assessment, exposure assessment, and characterization of risk. Special competence and careful consideration are needed to assess effects on human reproduction. There is often a lack of scientific information concerning, e.g., toxic influences of chemical substances on human fertility, pregnancy, and offspring. Legislation and guidelines concerning workplace exposures need further development in many countries. It is important that occupational health and safety personnel, as well as experts in this field, assist employers and employees in the development of good workplace policies for the protection of the reproductive functioning of male and female workers. A protocol for effective risk assessment is described.

Implementation of the precautionary principle in standards for the workplace

The objectives were to describe and discuss the current and proposed European occupational health policy on two categories of substances that pose serious effects: those potentially carcinogenic or genotoxic and those with toxic effects on reproduction. The precautionary principle was applied to setting standards for the workplace for those two categories of substances, to give an impression of the resulting limit values and the consequences of the implementation of this precautionary principle. A pragmatic approach was chosen as this starts with substantial indications of health risks. For the suspected carcinogenic or genotoxic substances 0.1 mg/m3 as a precautionary occupational exposure limit (precautionary OEL) is proposed. For the substances suspected of causing reproductive toxicity the precautionary OEL was derived in three ways, depending on the availability of data and of a current Dutch workplace standard (MAC, maximum accepted concentration): (a) by calculation based on available inhalatory animal data on the risks of reproductive toxicity; (b) by adding a safety factor of 10 to the current MAC, if no inhalatory animal data on reproductive toxicity are available; (c) by using 0.1 mg/m3 as precautionary OEL for substances suspected of having reproductive toxicity but without inhalatory animal data on reproductive toxicity and without a MAC.