Risk assessment birth defects

A two- to threefold increased risk of birth defects among children of Vietnam war veterans exposed to Agent Orange has been suggested by several epidemiological studies, but these studies have been criticized on a number of grounds, including exposure assessment, outcome verification, and potential for recall bias. Animal studies have not demonstrated clear-cut adverse effects of phenoxyherbicide exposure on reproductive outcomes. ... 

In residents of Seveso, Italy, a significant rise in the incidence of birth defects, as compared to pre-accident levels, was observed the year after the accident (Bisanti et al. 1980). A variety of birth defects were observed, but the incidence for any particular defect was not elevated. The authors suggest that the rise in birth defects may not be related to 2,3,7,8-TCDD exposure. Prior to 1976, birth defects in Italy were usually under reported the authors note that the reported incidences of birth defects after the accident (23 per 1,000 births) were similar to incidences reported in other western countries. Thus, the increased incidence may be reflective of the increased reporting rather than an increased number of birth defects. In a study which assessed the risk of birth defects for the 6-year period after the Seveso accident, no increases were observed for the risk of total defects (RR of 1.2, 90% Cl of 0.88-1.64 for zones A and B and RR of 0.97, 90% 0=0.83-1.13 for zones A, B, and R), major defects RR of 1.02, 90% 0=0.64-1.61 for zones A and B and RR of 0.83, 90% 0=0.67-1.04 for zones A, B and R), and minor defects RR of 1.44 90% 0=0.92-2.24 for zones A and B and RR of 1.14, 90% 0=0.92-1.42 for zones A, B and R) (Mastroiacovo et al. 1988). The small number of observed birth defects limits the statistical power of this study to detect significant increases in a specific defect. 

Kessel E. (1998) Quinacrine sterilization An assessment of risks for ectopic pregnancy, birth defects and cancer. Adv Contraception 14 81-90. 

The outcomes of pregnancy in 53 women exposed to lamotrigine included 4 spontaneous abortions, 13 induced abortions (none because of a prenatally detected defect), 34 newborns without birth defects, and 2 newborns with unspecified defects (66). No information on co-medication was given, and more data are required for risk assessment. 

Human health biomonitoring may also use animal surrogates in the environment to assess potential health hazards to humans - the proverbial canary in the coal mine . For example, chemical and biomarker analysis of bodily fluids or tissue biopsies from family pets, especially dogs, are sometimes used to assess potential chemical exposure and effects in children. This is because dogs often accompany children in the outdoor environment, and both have a tendency to (accidentally or intentionally) consume environmental media such as soil and surface water There has also been an increasing trend to use native animals as sentinel species, that is, fish, wildlife, or invertebrates that are indicators of possible human health risks from environmental hazards. For example, increased incidences of tumors or endocrine disruption in fish may indicate the presence of compounds in the water that may cause cancer or reproductive dysfunction in humans. Concern has also been raised over the increased incidence of deformities in frogs, because these may indicate an increased level of chemicals in the environment, which can cause birth defects in humans. 

Abstract. Scientific data show the association of population health status with environmental situation of residential area and working conditions. For ecologically induced or work-related pathology it is typical not only prevalence of chronic diseases including reproductive health disorders, such as pregnancy complications, but also health disorders in off-spring such as birth defects, diseases of newborns and children of early age due to parental exposures, etc. So risk assessment and management is essential for environmental and occupational hazards especially for chemicals for adequate reproductive health protection. 

---