Water Pollution and Humans

Common pathways for transport of toxins in the New York area are:

• Surface Water Pathways - wastewater and stormwater discharge during manufacturing releases PCBs to the whims of nature.
• Groundwater Pathways - groundwater discharge from plants, has been a source of PCB contribution to the soil and water column.
• Airborne Pathways - PCBs have been detected in the atmosphere of the Hudson River basin in New York and on vegetation due to atmospheric fallout.
• Food Chain Pathways - Bioaccumulation - PCBs are stored in fatty tissue of the food chain. Recent studies among fishing communities around the similarly polluted Great Lakes in southern Canada and the northern US suggest that the PCBs there are damaging children's neurological development - causing slow learning, poor memory and short attention span.

Water Pollution Toxins

In fish, dioxin exposure of eggs effects embryo development causing reduced hatchability and increased mortality during the -- sac fry -- stage. Laboratory experiments have shown high levels of PCDD/Fs in inland waters would cause early life stage mortality in feral fish, thereby reducing fish populations . Similarly, in birds the embryo is more sensitive to dioxins than adults. For example, since the 1960s there have been several reported declines in populations of colonial fish-eating birds, such as Rainbow Trout, in the Great Lakes in which dioxins have been associated with increased embryo mortality.

Human Exposure to Water Pollution

Human exposure to dioxins is almost exclusively from food intake, especially from meat, fish and dairy products. Unusually high exposure to dioxins in humans following for example accidental/occupational exposure, together with experiments in laboratory animals, have shown effects of dioxin on health include developmental and reproductive toxicity, effects on the immune system and carcinogenicity. Even more disturbing are findings from recent studies which show that concentrations of dioxins in human tissue in the general population (of industrialized countries) are already at -- or near-those levels where health effects may occur. Recent research on health effects from dioxin indicates the following important points :

• In fish, birds, mammals and humans, evidence shows that the developing fetus/embryo appears to be very sensitive to toxic effects of dioxin. Developmental effects in humans, seen after high accidental/occupational exposure to dioxins include: pre-natal mortality; functional alterations including effects to the male reproductive system.
• Biological effects from dioxins appear to depend on the concentration present in a target organ over a critical time period rather than on dose.