The threat of exposure to reproductive toxicants is not merely hypothetical or potential, but is absolutely real and yet preventable.

Children are more vulnerable to the effects of reproductive toxicants.

What can we do to prevent exposure to reproductive toxicants?

Reproductive Development, Congenital Anomalies and Endocrine Effects

What is the concern regarding reproductively toxic substances?

Substances that are reproductive toxicants alter the normal development, differentiation and adult functioning of the reproductive system.

As recent reviews have suggested, the threat of exposure to reproductive toxicants is not merely hypothetical or potential, but is absolutely real and yet preventable. We know from both animal and human studies that a number of substances that can alter reproductive development are liberally emitted into our environment. There is also evidence of adverse effects from some of these substances at current Canadian environmental concentrations.

Lastly, there is a great deal of uncertainty when it comes to reproductive toxicity from environmental exposures. There appears to be an increasing prevalence of fertility problems. Researchers suggest this is linked to the considerable volumes of hormonally active agents emitted regularly into the environment.

What substances can affect reproduction and reproductive development?

Among the major substances that are toxic to developing reproductive systems and that Canadians may encounter are:

• Heavy metals such as lead, mercury, manganese, cadmium, arsenic
• Organic solvents such as benzene, toluene, xylene, acetone, vinyl chloride, trichloroethylene, phenols, etc.
• Persistent organic pollutants (POPs) such as PCBs, dioxins, DDT and other organochlorine pesticides
• Other hormonally active agents including plasticizers such as phthalate esters
• Pesticides of the organophosphate and carbamate type

How are children exposed to reproductive toxicants?

The routes of exposures to reproductive toxicants are broad and vary depending on the specific agent. Most of our harmful exposures to reproductive toxicants come through the diet, through food and water, although in some cases they can be inhaled via air. Of particular importance to children is that they may be exposed in the womb, during infancy via breast milk, and from consumer products that contain or harbour such contaminants. Parental exposures prior to conception that lead to genetic damage in gametes may cause effects in offspring.

What are the potential health effects from reproductive toxicants?

There is a spectrum of reproductive and developmental effects depending upon a) the dose, b) the timing of exposure, c) the site of action and d) the sex of the exposed individual (or fetus).

The range of potential reproductive effects includes

• impaired fertility
• fetal death
• congenital abnormalities
• malformations of reproductive structures
• altered growth
• altered (delayed or early) reproductive developmental milestones

Attention has been focused of late on the potential role of low levels of hormonally active agents that disrupt normal endocrine functioning. While most information comes from studies of the effects in animals, there is concern that humans are at risk because of widespread low-level exposure to such agents.

Why are the young more vulnerable to effects from reproductive toxicants?

Athough there is incomplete evidence on sensitivity of the developing human reproductive system, it is likely that there are several windows of vulnerability for the reproductive system because of the complexity and distinct timing of the many processes involved. Critical windows of exposure occur preconceptionally, prenatally (during gonad differentiation, urogenital system and early breast development) and during early infancy, late childhood and puberty.

How does one prevent such exposures on a personal level?

There is a relatively broad window of susceptibility for reproductive effects, from prior to conception through to adolescence. The effects from reproductive toxicants may go unnoticed until an individual is reproductively mature and attempts to conceive a child. Therefore, avoiding exposures before they happen and before they can do greatest harm is the key strategy for personal prevention. Physicians can counsel patients, particularly if they are considering having children or are pregnant, regarding personal activities, choices in their diet and avoiding potential exposures in the workplace, home and community.

What do we do as a society to prevent these exposures?

Personal prevention strategies are only half measures at best, however. CAPE joins other health advocacy organizations in Canada and the United States in calling for precaution in health policies and environmental regulations to prevent harm to children’s health from reproductive toxicants. In particular, the identification and elimination of hormonally active agents in the environment is crucial because of the considerable scientific uncertainty combined with the risk of exposure and harmful effects for significant numbers of children and future generations.

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